TVP14 Training Manual

Training Manual

Course: TVP-14

Projection TelevisionTroubleshooting

Practical Troubleshooting Tips

RA-3/3A, RA-4/4A, RA-5A, RA-6 Chassis

KDP-57XBR2

Table of Contents1. Introduction .......................................1

The RA-3/3A Chassis2. The RA-3/3A Chassis ........................23. Power Supply Troubleshooting ......3The Main Power Supply ....................................... 6

4. Shutdown & Self-Diagnostics ........125. Deflection Circuits ...........................146. Video Process Troubleshooting:T & S Models .........................................20

The RA-4/4A Chassis7. Troubleshootingthe RA-4 Chassis ..................................29Overview................................................................ 29

8. Power Supply Troubleshooting .....30Overview................................................................ 30Standby Power Supply Troubleshooting .......... 30Unit will not Power Up ......................................... 34Shorted Switching Transistors ........................... 35

Regulator Troubleshooting ................................. 35

9. Protect Circuit Troubleshooting ....37Overview................................................................ 37

10. Deflection CircuitTroubleshooting ...................................40Overview................................................................ 40

Horizontal Deflection ........................................... 40Vertical Deflection ................................................ 44Vertical Deflection Troubleshooting .................. 46

11. High Voltage CircuitTroubleshooting ...................................4712. Video Circuit Troubleshooting.....5413. Troubleshootingthe RA-4A Chassis ...............................63Overview................................................................ 63

14. Video Circuit Troubleshooting.....64

The RA-5A Chassis15. Troubleshootingthe RA-5A Chassis ...............................67Overview................................................................ 67

16. Power Supply Troubleshooting ...68Overview................................................................ 68Standby Power Supply ........................................ 68Primary Power Supply ......................................... 68Troubleshooting the Primary Power Supply .... 70

17. Protect Circuit Troubleshooting ..73Overview................................................................ 73Troubleshooting .................................................... 75Shutdown - No Diagnostics Indication.............. 76

18. Deflection CircuitTroubleshooting ...................................7719. High Voltage CircuitTroubleshooting ...................................8020. Video Path Troubleshooting ........84

The RA-6 Chassis21. Troubleshootingthe RA-6 Chassis ..................................87Overview................................................................ 87

22. Power Supply Troubleshooting ...88General Description............................................. 88

23. Protect Circuit Troubleshooting ..9224. Deflection CircuitTroubleshooting ...................................9625. High Voltage CircuitTroubleshooting ...................................9926. Video Circuit Troubleshooting... 103General Description............................................ 103

27. Troubleshooting theAKB Circuits ....................................... 109Overview............................................................... 109

28. Auto RegistrationTroubleshooting ................................. 113Overview............................................................... 113Flash Focus Errors ............................................. 115Error Codes .......................................................... 119

29. Model-to-ChassisCross Reference ................................ 120

1

1. Features

Chapter 1 - IntroductionIn the fall of 1996, Sony Electronics introduced a troubleshooting course (TVP-06) that covered troubleshootingof the AP and RA-1 chassis, along with the prior EX and EXR model sets. The course provided some useful andpractical approaches to repairing failures that might occur in each of the circuits, and allowed the technician tofocus on troubleshooting more than theory of operation. Unfortunately, the RA-2 chassis was not included asthis product was just being released on the market. This chassis will not be covered in this course and since itshares much of the same circuitry as the RA-3, you should be able to apply virtually all of the troubleshootingtechniques covered in this course. For information regarding theory of operation for this chassis, refer to thetraining manual TVP-07 (P/N TVP070797).

Almost six years have passed, and six new chassis versions have been introduced. Some minor (and somedramatic) changes in circuitry design have occurred. High Definition Television was finally getting underway andthe competition for producing better performing projection televisions introduced new features that had neverbeen seen before. In some cases, new troubleshooting approaches are needed to effectively deal with thesenew circuit designs. Add replacement parts tracking and you have useful resources to document some practicalapproaches to solving problems that might arise.

The course will be organized by chassis group with a brief description of what was introduced in that family.Next, the major circuits with a brief description of each will be covered with some reasonable approaches toisolating problems. If you need more detail on the theory of each circuit, the appropriate training manual thatapplies will be mentioned.

NOTE: Much of the power supply troubleshooting techniques in this manual involve using a variac with either aseparate or integrated AC amp meter. If you do not have one, get one. You cannot perform speedy power supplytroubleshooting without one and risk the possibility of damaging newly installed components or causing thefailure of other parts along the way.

2

1. Features

Chapter 2 - The RA-3/3A ChassisOverviewThe RA-3 chassis introduced a major redesign in the convergence circuits that made it much easier for thetechnician to converge the set with greater accuracy and speed. It is know as Flash FocusTM and allowed thecustomer to perform more thorough convergence realignment should it drift out of range. The RA-4 was actuallythe first unit to introduce this feature a year earlier, but it was confined to the more expensive XBR200 seriesunits. The RA-3 brought this feature to the more affordable models.The power supply still utilized the dual transistor switching power supply that is found in previous sets, andincorporated the two transistors into a single IC package. A separate standby supply still exists but uses a FETtransistor for switching instead of a bi-polar type. Self-diagnostics were also introduced to aid in troubleshooting.

The number of circuit boards was substantially reduced with most of the circuits residing on the A and G boards.The G board now contained the deflection circuits, along with the usual power supply components rather thanutilizing a separate D board. Unlike previous sets, which had a separate horizontal scan and high voltagesections, the horizontal/HV is handled with a single output and flyback to generate H scan and HV. This makesdeflection and HV problems easier to diagnose. The A board handles video processing, system control and theFlash FocusTM circuit. Pincushion correction was simplified by substantially reducing the number of discretecomponents.

The RA-3 also provided the customer with component video capability, which was previously found only on theXBR series. The T and S series models provided a single component input at the rear in the video 4 slot while theV series provided for two components inputs at video 4 and 5.

There are not any significant differences between the RA-3 and RA-3A worth mentioning. In fact, the circuits arealmost identical with some minor design changes. The RA-3A chassis was simply a carry-over into the nextmodel year, so the troubleshooting procedures remain the same for both. To keep things simple, only the RA-3in the titles and text portions of this section will be mentioned.

3

3. RA-3/3A Power Supply Troubleshooting

Chapter 3 - RA-3/3A Power Supply Troubleshooting

he Standby Power SupplyThe standby supply is a simple switched-mode type utilizing a single transistor, transformer and feedback circuitryto generate approximately 7VDC provided to a 5-volt regulator IC. Regulation will be provided by changing theoscillation frequency based on current demand. Notice that the regulated 5 volts not only provides standbypower for the microprocessor, but also powers the main relay. This is a deviation from previous designs. It isimportant to remember this when the need arises to replace the relay and you are obtaining one from a scrapboard that came out of an earlier chassis. The relays in previous projection and direct-view sets were rated at 12volts and will not function on this chassis.

Referring to Figure 3-1, the supply works by supplying unregulated B+ through the primary of T602 to the drainof Q601, which will provide the needed ground path via R604 to provide current for the transformer. Q601 G willneed a kick-start and that will be provided by R609. The FET will now begin conducting and current will begin toflow through the primary. The feedback winding at pin 4 of T602 will now start generating a positive voltage,thereby charging C614, which will drive the FET harder. This increases current in the primary, which furtherincreases the feedback voltage, which further increases the conduction of the FET. This event will continue untiltwo things occur: Q601 reaches saturation and C614 charges. This is how the on time of Q601 is controlled tochange the frequency.

C616 will route the feedback voltage via R615 to Q602B. This voltage will be smoothed out by C610 and C609to provide a rising sawtooth to control the on time of Q602. Q602 will now become part of the RC network ofC614, R608 and R616. If current demand on the secondary of T602 decreases, voltage levels in the transformerwill rise accordingly. This will cause a rise of the feedback voltage and will cause Q602 to conduct harder andalter the RC time constant. C614 will now charge more rapidly and Q601 will turn off earlier. By shutting the FEToff earlier, the on time is decreased along with the duration of the field collapse in T602. Shorter conduction timeand field collapse equals faster switching cycles and, hence, higher frequency. The higher the frequency, thelower the output voltages at the secondary.

Q602 will also provide protection against over-voltage or over-current situations. If the current rises dramatically,a voltage drop will occur across R604. When it rises to 0.6V or more, Q602 will conduct to raise the frequency,or, in severe cases, momentarily stop oscillation. This would cause the familiar “ticking” noise as the supplykeeps trying to re-start.

Should the regulator loop fail, zener diode D605 will monitor the voltage stored by C618, which is charged byD610 during the field collapse periods. If this exceeds 6.2 volts, D605 will fire into Q602B and produce the samereaction as an over-current condition.

4


FB621

D601

D602FROMT601/1AC HiSIDE

R6074.7 OHMS

R620 C617

D623

Q6012SK2845

R608

C609

C608

R604

HOTGROUND

R609

R605

Q602PROT. C613

C614

R616

D607

D604MTZ-T-77-15

D605RD6.2ESB2

C610

R638 D610

C618

FIGURE 3-1 - STANDBY SUPPLY

D

S

2TVP14 7/11/02

G BOARD

R622

T602SRT

D667

C676

IC6555V REGBAO5T

CN605

C650STANDBY+5V TOA BOARDCN681

TO RY601POWER RELAY

6

5

4

3

2

1

11

10

9

8

10

7.2VDC

I OG

C616

R615

TroubleshootingThis supply should operate reliably since it only feeds a few circuits and the current demand is minimal.Unfortunately, as this supply is always running so long as AC input is supplied, it will be susceptible to linetransients. The main supply will be protected as long as the main relay is not engaged and the transient is notlarge enough to jump the open relay contacts (such as a heavy lightning strike). Failures that might occur wouldbe a dead supply or regulation problems.

If Q601 has shorted, there is a high probability that something else caused the failure. This is based upon areliable history of this component. We will start with a scenario of a shorted Q601 and then cover a “no run”condition next since you are most like to end up with this after replacing Q601 due to current or transient causes.The FET gate has very high impedance, which allows other components to suffer damage.

Dead standby supply - Q601 shortedUpon replacement of the shorted FET, the main concern is what caused it to fail and to prevent it from failingagain when power is re-applied. The most valuable piece of test equipment in this situation, as mentioned in thebeginning of this manual, is a variac with an AC current meter, either separate or integrated with the voltagemeter. This will assist by indicating current conditions, and allow you to control that situation and prevent failureof the newly installed FET.

5


Once the FET has been changed along with R607, you will need to disconnect the secondary voltage line bylifting D667. This is very important since switch-mode supplies draw very small amounts of current while runningunloaded and the load from the 5-volt line must be kept from drawing any current. Many technicians are fearfulof running switch-mode supplies unloaded. Most are able to run unloaded, but this test is not going to supplymore than 40VAC. You will need to keep the AC low with the variac and watch for current draw. While turning upthe AC voltage, monitor the drain of the FET with an oscilloscope to ensure it is starting to oscillate. This willneed to be done because even if the oscillator starts running, you will probably not be able to detect any currenton most amp meters that come equipped with the variac. If you do not see any oscillation by the time 40 or50VAC is reached, there is a problem.

Oscillator starts with very little AC current being drawn: Re-connect the load to the secondary and bring up thesupply with the variac while monitoring both AC current AND the voltage at D667. You want to ensure thatcurrent draw continues to remain low and that the input voltage to IC655 does rise dramatically above 7 volts.Rising current would indicate a short on the secondary or the output of IC655. A continuously rising voltage atD667 indicates regulation problems. Regulation problems will be discussed later. If the supply runs with full ACand minimal current, the repair has been completed

Oscillator starts with excessive current: This is an obvious indicator as to what caused Q601 to fail. This situationis rare in this type of power supply in an unloaded condition but when it does occur, it is almost always caused bya leaking or shorted feedback coupling capacitor (C614) or shorted winding(s) in T602. Ringing the transformeror viewing the waveform at Q601D will expose problems in the windings. Listen for any ticking sounds and watchthe oscilloscope for bursts of oscillation, which would indicate the over-current and/or over-voltage stages aredoing their job.

Dead Standby Supply – Q601 not ShortedAssuming very little AC current is being drawn and there are no chirping or ticking sounds, you are dealing witha circuit that is not starting or is not able to sustain oscillation. Verify the presence of B+ at Q601. Next, read thevoltage on the gate of Q601. The same voltage present on the drain should appear at the gate

No voltage at gate: No voltage indicates either an open start resistor (R609) or the gate is loaded down. Readthe resistance at the gate of Q601 relative to hot ground. It should read infinity. If it does, lift one side of R609and read its resistance. You must lift it since it is a 22MΩ. If resistance is read at the gate, you will need to findthe component(s) at fault. As mentioned earlier, due to the high impedance of the FET gate, many componentscan be damaged by incoming transients. Even a small amount of leakage can overcome the pull up function ofR609. All you can do here is to “ohm out” parts or, more effectively, lift components to get the voltage back on thegate. In the case of line transient damage, you may find several components loading the area down. Do notforget about feedback capacitor C614 since it is connected to the feedback winding with a low resistance toground.

Voltage present at gate: This indicates the start resistor, R609, is OK and nothing is loading the gate. You nowhave a narrow choice of components to check. Either the feedback path is open (C614, R616 or the feedbackwinding itself), or the “tuned” portion of the oscillator has a problem. This leaves us with leaking or, most likely,shorted C617 or D623 in the snubbing circuit or T602 itself.

Voltage Regulation ErrorsThis failure can be difficult at times due to the closed loop needed for this circuit to operate. It becomes evenmore difficult when the problem is excessive B+ since components can be damaged. Listed below are sometroubleshooting techniques:

Low B+ -This is easier to work on since you will not risk damaging components. Excessive current is not being drawnsince components are not smoking. It is safe to assume the regulation feedback loop is not open since thiswould cause B+ to run too high. That leaves two possibilities: 1) The oscillator is incapable of producing adequateB+ due to frequency shift or distorted oscillation; or 2) the regulation control components are not performing their

6


job properly. Since they are part of a loop, one affects the other. This is where many technicians run intodifficulties. It is similar to working on vertical deflection circuits. They are one of the more simple circuits in atelevision but seem to be one of the more difficult to diagnose because of the reliance on feedback. The first taskis to isolate the failure in either the feedback loop or the oscillator. This can be done in a surprisingly simple way.

The regulator loop will be opened. It can be done safely so long as you have the variac. In this situation, you willwant to remove the connection from Q602-C to Q601-G. Slowly apply AC voltage with the variac while monitoringthe input to IC655. Proper B+ on the secondary line should appear at low AC. If it does, the problem is in theregulation loop. The nice part of this method is that it divides the number of suspected components in half. Hereare the two possible outcomes:

B+ is still low even with full AC input: Assuming proper unregulated B+ is getting to Q601, either theoscillator feedback line (not to be confused with the regulation feedback) is impeded or the oscillatorcircuit is noisy or out of frequency. Suspect dry capacitor C614, resistance increase in R616 or loading ofthe feedback line by shorted or leaking D604, D607 or C613. Q601 could even be the cause.

B+ reaches full level at low AC input: The problem is in the regulation loop and is usually caused by noisein the line and open filters. C618 is a good suspect. If it opens, noise spikes will overcome the zenerdiode D605 and will be amplified by Q602. Watch out for filters C609 and C610 opening or increasing invalue. Their job is to help produce a nice ramp-shaped signal at the base of Q602. This is especially truefor C610. The rise time of this ramp is critical in the timing of turning off Q601. A leaky C618, or evenQ602 itself, is another possibility.

Excessive B+This problem requires caution since damage to components is a possibility. By far, the most likely component isgoing to be Q602. Based on previous experience with this type of power supply, the B-E junction is common toopen. Leaking or shorted C610 comes in at a close second. Check for an increase in value, or open, at R615,and a decrease in value or open at C618

The Main Power SupplyThe main power supply is still a somewhat conventional style that has been used in Sony televisions for manyyears. It is only active when the unit is powered up by energizing the main relay RY601. It has earned a dubiousreputation amongst technicians due to its insatiable appetite for several sets of switching transistors before thetechnician finally got it repaired, and, rightfully so. When there are two transistors working together and one issupposed to be off while the other is on, extreme care must be taken when replacing them. You are going tolearn some nice tricks that will virtually eliminate the immediate destruction of your newly installed switchingtransistors. The regulation principle, although appearing complicated, is quite simple to troubleshoot since itrelies on pure DC voltages to function rather than ramp-rise timing used in simpler switching supplies.

OperationRefer to Figure 3-2. The switching transistors are now conveniently packaged into a single IC. Oscillation isbegun by the upper transistor in IC601. Its collector is connected to the unregulated B+. R610, R611 and R619bias the transistors near conduction in a classic AB-type amplifier design. The upper transistor will start currentflowing into the primary of T604 at pin 2. Pin 1 will continue the current flow to pin 5 of T605 and exit at pin 6where C602 will provide the path to hot ground. This will cause pin 3 of T604 (the feedback winding) to spike thebase of the upper transistor through C620 and R619, which will now begin conducting. Current will increase inthe primaries of T604 and T605 and continue to charge C602 to the ground return. The feedback output at T604/pin 3 will continue to increase and turn the upper transistor on harder. Meanwhile, the lower transistor is beingkept off since its base is connected to another feedback winding via R617 and C621. This other feedback sourceis 180 degrees out-of-phase with the other so it is a negative voltage at this time.

7


Once C620 has charged, the upper transistor will lose its large B-E current and turn off. The impedance of theprimary in T604 will determine how fast C620 is charged and this will vary depending on the amount of current inthe control winding at pin 7 and 8 of T604. This is how this supply will regulate. The field will not collapse and allinduced voltages will reverse polarity. The feedback voltage at T604/pin 3 will now go negative and pin 4 will gopositive and turn on the lower transistor in IC601. IC601’s job is to pull pin 2 of T604 primary to ground potential.The voltage stored in C602 will now have a path in which to discharge so that it is ready for the next cycle whenthe upper transistor conducts again. The oscillator can continue this cycle indefinitely as long the componentsremain stable and external power is available. All that needs to be done now is to alter the on-off time of theswitching transistors in order to regulate the secondary outputs.

The winding at pins 7 and 8 of T604 is what is known as a “cross winding”. The more current that flows throughthis winding, the lower the net inductance of the windings in T604. It is similar to the effect that occurs whenadjusting the ferrite core in an adjustable coil or transformer. By lowering the inductance, the primary of T604 willprovide less resistance to current changes and will allow C602 to charge faster. If it charges faster, the fieldcollapse will also be shorter in duration and you now have a shorter charge/discharge rate and, hence, higheroscillation frequency.

The current in the control winding is handled by IC654. It monitors the 135V B+ line. If the 135V line were to rise,IC654 would act as an inverter. Pin 7 of T604 is fed by 18 volts from the secondary of T605. Since IC654 inverts,it will pull down pin 8 of T604. Current through the control winding will increase, the impedance of T604 willdecrease and the oscillator frequency will rise. This will move the frequency further above the fixed resonantpoint of T605, which will increase its impedance. The net effect will be a drop in secondary output voltages. Theopposite will occur should the 135V line decrease.

One more item to cover: The “soft start” circuit. This circuit is important to understand since its failure can causemajor problems for a technician. When the main power supply is first energized, a large current surge will occursince the oscillator is starting from zero frequency and rising (which will cause it to cross the resonant point ofT605) and all of the filter capacitors on the secondary lines are waiting to be charged up. Consequently, it isimportant that the oscillator be “forced” into high frequency as soon as possible. Q653 is allocated to this task.There is a constant 12V source provided to the control winding by Q651. If it were not there, the control windingwould have no voltage at initial turn-on. As mentioned earlier, this would cause low frequency oscillation and,hence, maximum output. This condition is undesirable while all of the filter capacitors are charging as it couldcause IC601 to fail.

Q653 is connected to the return side of the control winding through R669. Its base has a 1mf capacitor connectedto it. This capacitor provides approximately three seconds of charge time to keep Q653 on, which will providepull-down to the return side of the control winding. Extra current is now provided through the control winding tokeep the oscillator frequency high during the initial turn-on period. Once C673 has charged, the base of Q653will go high and it will turn off and hand over control to IC654. Problems in this circuit can cause instant failure ofthe switching transistors or may cause them to fail weeks later after the repair. A five second test can be done tocheck this circuit and this will be covered in the troubleshooting section.

8


C622

C624

R6192

3

1

4

5

6

5

4 3 1

5

22

A BOARD

7 8

R654

C662

T604 PRT

D666

D603

C602 R610 R611

C620

IC601MXO8

41AB-F

C612

N

2

1

RY601

12VSTBYHOT

GND

R6020.8220W

ΩC611

C612

P

12V STBY

Q651 BACK-UPR668

D662

R617

C621C623

2

IC654 DM-48

+135V

FROM IC001/62

CN1601

CN652

R677

R673

TOPROT.LATCH

Q652RY

DRIVENQ658

LIMIT

N

R681

R680

R679D665

C673 R676

P

Q653SOFT

START

R669

R666 C670 R670 C671

D66824V

R683

R621

R618

D665

C659

C658

D658

R655

C664

D660D659

R656

R652

T605PIT

AUDIOGND

AUDIOB+

AUDIOB-

+5V

-5V

+15V

-15V

18V

FIGURE 3-2 - SWITCHING POWER SUPPLY

AC

50V/DIV 5uS T/DIV

1/2W

ΩR612 0.1

G BOARD

1TVP14 1448 7/17/02

IC652

IC653

9


TroubleshootingOnce a few standard procedures are followed, this power supply is not too difficult to repair. The greatestobstacle is the precise timing required for the two transistors inside of IC601 to work together. They form aclassical AB-type amplifier design. This means the transistors need to be biased near the upper end of the cutoffpoint and this is provided by resistors R610 and R611 for the upper half and R621 and R618 for the lower.Anything upsetting the biasing of the feedback lines can cause an overlap. Once both transistors are on at thesame time, even for a brief moment, they will fail. Incoming transients from the AC line, excessive noise in thefeedback circuit or leakage of the coupling capacitors C620 or C621 can cause this to happen. The other causemay be excessive current that exceeds the capacity of the transistors, such as shorts on the secondary line.Problems in the feedback circuitry are the most difficult for the technician. In a typical situation, the technicianfinds IC601 shorted and checks the secondary lines for shorts. He then fires the unit up and loses the newlyinstalled IC. This problem can be solved by using a proven method to actually run the supply with the originalcause still there, and yet not lose the switching IC. Also covered will be regulation problems, which are quiteeasy to solve with a couple of simple tricks.

Since the most common failure is shorted switching transistors, that scenario will be covered first. Power suppliesthat will not run is not very common, but will also be covered. Regulation troubleshooting will then follow.

Dead Power Supply, IC601 ShortedThe important rule to remember when this happens is to assume that something caused the failure. Occasionally,IC601 will simply fail and will turn out to be an easy repair. However, you should be ready for the likelihood thatsomething else is still wrong. Rule number one is: Never fire up the set to see what happens. Always use avariac to bring it up slowly. There is one problem to deal with before this is done. The main relay will not engageuntil there is at least 60VAC coming into the set. This will supply enough unregulated B+ to the switchingtransistors to generate full secondary voltages and they will be lost if a dynamic load (such as a defective flyback)or a shorted line still exists that was missed during the performance of static resistance checks. It is going toinvolve jumping the main relay while controlling things with the variac. This is a safe method so long as care istaken and the current is monitored closely.

Some technicians like to use a light bulb in series with the AC input to protect against failures. This worked fineon analog supplies, but all it did was sit there glaring at you to indicate a problem existed. It is not a good idea touse this method on switching supplies. The light bulb will substantially reduce the incoming AC voltage and,consequently, the unregulated B+. The power supply will now go into low frequency mode and try to get theproper secondary voltages. This will produce greater “on” times for the transistors and they will soon overheatand fail. Use a variac.

Once IC601 has been replaced (it is assumed that fuse resistor R612 will also need replacement), some otherchecks are required before power is applied. A quick visual check of the components around the switching ICshould be done to look for signs of overheated parts. Watch the small capacitors for signs of cracking orswelling. This is particularly important if lightning activity has occurred recently. Check all secondary voltagelines for shorts and if all is OK, it is time to apply some power.

Plug into the variac and set the meter for AC current if it is an integrated type. Jump the relay RY601 and startbringing up the AC voltage. Watch the current draw closely. At around 40VAC, about 750ma to 1 amp will shouldappear. Continue to increase the voltage and allow up to 1.5 amps to appear, but no more. As you near 60 to70VAC, the amperage should actually start decreasing as the voltage input rises. As the switching supply getsmore voltage, it will increase its frequency due to the transistors having a shorter on time. By the time you reachfull 120VAC, the amperage should have dropped to somewhere between 600 and 800ma. There is a goodchance you now have a repaired unit, but there is still one more check to perform. The soft start circuit couldhave caused the IC failure and if this is so, IC601 will fail at turn-on. This may happen immediately or evenweeks later. Move forward to the section dealing with soft start. Unfortunately, it does not always go this easyand a couple of different scenarios might occur from the ideal outcome above. Following are some suggestionsfor resolving them:

10


No AC Current Is Read: You have a supply that will not start. This is not common, but can occur. Bring the ACvoltage up to 40 volts. It is recommended to not exceed this level just in case you accidentally cause theoscillator to start while probing around with the scope and meter. The first important step is to measure thevoltage at the collector of the upper transistor. There should be a DC voltage present that is approximately twicethe AC voltage due to the doubling circuit. The next point to read is the collector of the lower transistor. Sinceboth transistors are biased slightly above cutoff, one half of the voltage level that is read on the upper transistorshould be here. Both transistors are identical and so are their bias resistors. Consequently, this comprises avoltage divider. This is an excellent test to see if the bias resistors are good and both transistors are able toconduct. If the voltage is significantly higher or lower at the mid point, possible causes are an open bias resistor,shorted feedback coupling capacitors, shorted C612 (this would cause the same voltage to appear at bothcollectors), or a defective IC.

If the DC voltage is being divided properly, there is likely a problem with the feedback circuits, an open windingor solder connection problem at either transformer, or C602 could be open. It is possible that feedback capacitorsC620 and C621, or R617 and R619, are open since they handle significant current during their operation.

AC Current Rapidly Rises With Low AC input: This is where close attention will be required. The original causeof the switching IC failure is still there and needs to be located. Since you have checked for static shorts on allthe lines, there is a possible dynamic load problem and the power supply needs to be running in order to locateit. By keeping things under control and monitoring AC current, the failure of the switching IC can be prevented.This test can be safely performed even if the horizontal output transistor is shorted.

The cause of the over-current problem needs to be located and it will be in one of two places: either the primaryside or the secondary side. Since problems in horizontal and high voltage circuits are the most common, a handytrick is to disable the horizontal section by unsoldering the horizontal output transistor and re-applying AC voltage.If the current problem is gone (the current will not go much higher that 250ma with the horizontal circuitdisconnected), the over-current source has been exposed and will be dealt with in the section on the deflectioncircuits.

If excessive current still exists, its simply a matter of disconnecting secondary lines and trying to re-apply power.If disconnecting secondary lines does not resolve the issue, the problem is in the primary circuits. The switchingtransistors are either overlapping (conducting at the same time) or there could be a problem with T604 or T605.In almost all cases, one of the feedback coupling capacitors (C620 or C621) is leaky. This is more likely to befound in older units or ones that have incurred a large line transient. Watch the waveform at T604 pin 2. It shouldbe a relatively symmetrical square wave with a 50/50 duty cycle. Any evidence of ringing could indicate a shortedwinding in either of the transformers.

The Soft Start Circuit Check: As mentioned earlier, this circuit can cause switching transistor failures. Since thesupply was brought up slowly with the variac, the soft start has already been performed. The set has beenrunning for a while now and you are confident that everything is OK. The back cover is put back on and just tocheck one more time, the set is plugged in and turned on and the power supply fails again. The set may turn onjust fine but be returned anywhere from a few days to even weeks later with the power supply gone again. Whileother problems could be causing this, it is a wise idea to check the soft start circuit on any power supply in whichyou have just changed shorted switching transistors to avoid that dreaded call-back from showing up. Here is avery quick way to check the circuit:Bring the unit up slowly to full AC with the variac. Set the meter to read AC current, if necessary. While leavingthe variac at full 120VAC, turn the unit off with the remote or front power button. Wait about two or three secondsand turn it back on while closely watching the AC current. It does not matter what the current level is since thiswill vary from model to model and the quality of your incoming line voltage. What you should see in about threeseconds is a rapid increase in current of about 200 to 300ma from the initial current reading. That was the softstart circuit at work. If the current does not jump, find out why the circuit is not working. Suspect a dried-outelectrolytic capacitor C673, a shorted B-E junction or an open Q653 or shorted Q656.

11


B+ Regulator TroubleshootingB+ Voltage Too High: This symptom can be a little troublesome to work with because the unit will be going intoshutdown protect and there is the possibility of damaging components (particularly the horizontal output transistor).Once again, the main relay is going to be jumped, but this method works quite well if the proper steps arecarefully followed. Make sure that the unit is in the off mode. Turn on the set and let it go into shutdown. It isimportant to follow this step. The main CPU must be kept in the “power on memory” mode. If it is not, the relayon command will not go high and Q656 will hold the soft start circuit on and interfere with your diagnosis.Jump the main relay RY601. Bring up AC voltage with the variac, while closely monitoring the 135V line. As soonas 135 volts is reached, bring up the voltage to about 137V. It is OK to go this high since the protect circuit doesnot even activate until 139V or more. The purpose of this procedure is to determine whether or not the regulatorstage recognizes the over-voltage condition. Read the voltage at T604/pin 7. There should be at least 12VDCpresent. If not, the 18V line has failed coming from T605/pin 2. Failure of this line is rare so it should be there.Next, read the voltage at T602, pin 8. It should be dramatically lower than pin 7. If it is not, the problem is beingcaused by a lack of current through the control winding since IC654 is not pulling down on pin 7. Before you optfor replacement of IC654, keep in mind that this IC is very reliable. Many have been changed needlessly. Thiscondition is usually caused by the B+ voltage sampling resistor(s) such as R668. It increases in value and theregulator is fooled into thinking there is insufficient 135V.

If the voltage at T604/pin 8 is much lower than pin 7, either the control winding is open or IC654 is aware of the153V being too high and is trying to correct the problem by inducing more current into the winding. Assuming thewinding is not open (extremely rare), all that is left is an oscillator section has drifted so far off frequency so as tobe “out-of-range” of the control circuit. This can be caused in older units by dried out capacitors. Any of the smallvalue capacitors in the primary oscillator can cause this, so it is recommended to replace all of them to get thenormal frequency back in range.

B+ voltage too low: This is a little easier to work with since the risk the damaging components is not present. Weknow that excessive current is not causing the problem since the set is not going into shutdown. Simply read thevoltage at pins 7 and 8 of T604. If they are equal, IC654 is responding properly to the condition. Troubleshootthe primary circuits for oscillator distortion or frequency shift. If pin 8 is lower than pin 7, and this will usually bethe case, suspect Q653 soft start is constantly on or shorted or IC654/pin 4 shorted.

NOTE: On a properly working power supply, it is sometimes normal to be unable to reach full B+ level with therelay jumped. It depends on whether or not the microprocessor is in the “on” state. If it is not, the relay highcommand will remain low and Q652 relay drive will be off. This causes Q656 to remain on, holding the base ofQ653 low. This keeps the unit in “soft start” all the time. The purpose of Q656 is to discharge C673 at turn-off sothat there is always a soft start when the unit is turned back on. If the unit happened to be in the “power on” statewhen last running, the B+ level will rise to proper potential with the relay jumped. This is very important toremember when troubleshooting OVP problems as the soft start may kick in and interfere with regulator checks.

12

4. RA-3/3A Shutdown and Self-Diagnostics

Chapter 4 - RA-3/3A Shutdown and Self-DiagnosticsOverviewAnother new feature introduced in the RA-3 Chassis is self-diagnostics capability. By utilizing the timer LED onthe front panel, it can be flashed in sequences when a failure occurs to assist in troubleshooting. It works ratherwell in most situations, but can also mislead the technician. The unit will also store these failure events into theNVM IC for viewing and these can be called up by pressing “display” “5”, volume down” and “power”. This pageis only useful for troubleshooting intermittent problems since if cannot be displayed if the unit is going intoshutdown or video blanking. For a more detailed description of the shutdown circuitry, refer to training manualTVP-10 (P/N TVP100100).

Below is a sample of the diagnostics page:

Self Check

2: +B OCP 000

3: +B OVP 000

4: V Stop 000

5: AKB 000

6: H Stop 000

8: Audio 000

101: WDT 000The numbers on the left indicate how many times the timer LED flashed, which designates the probable cause ofthe shutdown. The flashes on the LED will occur at one second intervals, followed by a three second separationperiod and repeat again. The numbers at the extreme right indicate how many times the problem occurred up to999 events. You can see why this is beneficial for intermittent troubleshooting. It is always a good idea to clearthe events before exiting and that can be done by pressing “8” and “enter” on the remote. This is not the sameas pressing these buttons in the service mode. It will only clear the events and not reset customer defaults.Beware that the service manual instructs you to enter the service mode to clear these and that is a mistake. Youcan do it right from this screen. Below is a description of each event:

+B OCP: Excessive current on the 135V line. This is usually caused by flyback problems or secondary loads onthe line. The circuit could also be tripping for no reason. This is why you should always monitor AC current whilethe unit is shutting down. It will help to determine if the problem is actually an over-current condition and morecaution can be taken when servicing the unit.

+B OVP: The 135V line has exceeded 139 volts. Go back to the section on troubleshooting regulator problems.

V Stop: The vertical deflection circuit has stopped operating. This indication can also occur if the high voltagecircuit fails since it supplies the +15V and –15V supply rail to the vertical output. Loads on the I2C data and clockbus can also be the source of this problem.

AKB: One or more CRT cathodes are unable to generate sufficient current to return a good feedback pulse. TheAKB detect circuit may also have failed. It is common to see multiple AKB events in the diagnostic page alongwith registered HV failures. See the special section on AKB in Chapter 27 of this manual.

H Stop: The horizontal deflection has been turned off due to excessive high voltage. This will be covered in thedeflection section.

Audio: DC voltage has been detected on one or both of the audio out lines. The set is shut down to protect thespeakers. This is usually caused by shorted audio amp IC406.

WDT: A communications error has occurred. The main CPU is unable to communicate with the Y/C jungle IC.The timer LED blinks continuously at one-second intervals and as soon as 101 of them occur, a failure is registered.

13

4. RA-3/3A Shutdown and Self-Diagnostics

5

6

2

3

7

1

8

4

8

9

8

74

R665

R664

R663R659

R661

D672

C662

C663

R691

D674

D675MTZJ10B

D663

D661

Q654

R675

Q655

Q658

R690

D680

D676MTZJ-3-9BC680

R686C679

R687

C676

D667

D651R688

D664MTZJ-2-7A

IC655BAO5T

5V REG.

I

G

O

R689

R662

R657

R654

R667PARTOF T602STB

STANDBY5V

TOQ652/BRELAYDRIVE

OVP

OCP

RELAY

TO RY601 POWER RELAY

+135V

FROMD652/AAND D653/A

STANDBY 5V

RY DRIVEFROMQ652/C

IC651OVP/OCPuPC393C

-

+

-

+

+135VBRIDGENEG.

FIGURE 4-1 - POWER SUPPLY PROTECTION

PROTECTIONLATCH

CN605

TO CN681A BOARD

R681

R660

TO Q656/B LIMITER

4.1TVP14 7/11/02

R682

D66824V

Q657

C678

D66913V

R684+18V

+11V

G BOARD

Protection Circuits Not Covered By Self-DiagnosticsThere are four protect circuits that are not monitored by diagnostics. Consequently, they will not be identified bythe timer LED or stored into the diagnostics page. Referring to Figure 4-1, the standby 5V regulator IC655 isprotected against over-voltage to its input and excessive current at the output. The 11V line on the secondary ismonitored for excessive current (or a complete loss of it). The 18V secondary line is also monitored for over-voltage. If the unit goes into shutdown with no diagnostic indicator, this is where you will want to look next. Hereare some quick methods to locate the source:

The Standby 5V Circuit: Monitor the anode of either D675 or D674 while applying AC power. An oscilloscope orpeak-hold DVM is preferred, but this can be done with a standard DVM. If anything higher that 600mv appearsat this point (you will see 10V or more if this circuit is firing), the input voltage to IC655 is exceeding 10V and firingD675. Troubleshoot the standby supply regulator circuit described earlier in this manual. If D675 is not firing,read the voltage across Q658 B-E. If it is 600mv, the OCP circuit is activating. Locate excessive load on standby5V circuit. If Q658 B-E remains at less that .6V, monitor Q658 collector while re-applying AC. The voltage hereshould be zero. Any rise indicates excessive 18V or loss of 11V.

18V and 11V Protect: Monitor the voltage at D669 cathode while applying AC power. If voltage peaks at 11VDC,suspect 11V line failure or shorted D669. Normal voltage should be around 18V. If the voltage at Q657-E ishigher than 24VDC, the 18V line is too high. If both voltages check OK, look for leaking or shorted zener diodesD669 or D668. Q657 may also be leaking or shorted.

14

5. RA-3/3A Deflection Circuits

Chapter 5 - RA-3/3A Deflection Circuits

HSYNC

IN

FIGURE 5-1A - HORIZONTAL DEFLECTION (PART 1)

46

40

41

43

52

10 10

25

4

3 6

5

41

C517

C535

C534

C516

C521

C527

D518

D517

149

6

37

1310

11

TOT504/PIN 1

TO T502 PMT/PINS 3,4,7

TO PIN1H+ ZR

Q502H OUT

Q503PIN AMP.

D520

+12V

+12V +12V

IC502 1/4

IC502 1/4

IC502 1/4

TO DYNAMICFOCUS BIASRECT. D517

N

C510

XTALX203

IC206Y/CJUNGLE

CXA2025AS

+9V

HD

HP

E/W

CN502

CN801 R502

C501

Q501H DRIVE

R501C502

R509

C506C508

R506

R507

R508135V

T501

D501 5.1VHP LIMIT

TO HWAVE GEN

IC802/1

R519FROM ABL

R529

R528

C515

R524

R527

+12V

D513

C529

R530

R563

R556

C538

C531

+12V

R526

R523

L503

R527R509

C514

R532

C523

C518

R531 R535

R525

R551R543

R550

C528 R542

C537 +135V

HP -

+

-++

-

5.1ATVP14 7/17/02

G BOARD

OverviewLike the RA-2 chassis, the RA-3 utilizes a simple deflection circuit design much like those found in many of thedirect-view models. Figures 5-1A and 5-1B illustrate the simplicity of this design. High voltage and horizontalsweep are accomplished with a single horizontal output transistor driving a flyback transformer and deflectionyokes. This helps to simplify CRT protection and the need for horizontal sweep loss protection is not requiredsince there will be no high voltage to burn the tubes. The vertical deflection circuit remains relatively the same asthose in previous years.

15


TO ABOARDIC206PIN 43

H+

H-

DYR1

4

2

6

7

5

3

10

9

8

2

1

4

6

3

1

5

T504 FBT

CN506

CN505

CN504

C541

C549

R532

C542

C531

D532

L504 HLC

T502PMT

R594

C550 R544

-4V

+4V C547

C543L505

TO HYBLOCK

TOABL

TOFOCUSPACK

D528

R586

R566

R598

G BOARD

+

-

-

+

200V

135V

TOHEATERS

+12V

-12V

FROMQ502

H OUTCOLLECTOR

TO D518,L503,Q503,

PIN AMP.

1 1

4 4

1 1

4 4

1 1

4 4

FIGURE 5-1B - HORIZONTAL DEFLECTION (PART 2)

C546

5.1BTVP14 1451 7/17/02

DYG

DYB

21

R538R536

61

7C516

+

R584

D522R548

C536

CN502R545

IC502

R511135V

D507

D5067.5V

R522

+

-

High Voltage and Horizontal Deflection TroubleshootingThree major issues usually arise when a failure occurs in this circuit. Either the horizontal output transistor fails,the high voltage protect circuit engages or pincushion problems develop.

Horizontal Output Transistor Failure: Occasionally, you will be fortunate to have the output transistor fail andnothing else is the cause. Many times, however, you end up losing the newly installed transistor. In the worstcase, this will cause the power supply switching transistors to fail. Always treat a shorted horizontal output asthough something else caused it to fail. The use of a variac and an oscilloscope will help insure this.

16


Once the new transistor has been installed, it is always a good idea to re-solder the connections on the horizontaldrive transformer. These transformers handle a lot of current to forward bias the B-E junction of the outputtransistor. They get hot and run at high frequency, so it is common for solder connections to go bad. Solder theconnections very well. You want the solder to flow up into the internal pin connections at the windings. With thatdone, it is time to apply power.

Jump the main power relay. Place your scope probe somewhere near the horizontal output transistor. Mostscope probes are not able to handle the direct spike level from the flyback so this is a safe method. Turn up thegain a little on the scope and you will easily see the horizontal retrace pulse. Slowly apply AC power with thevariac and watch for the horizontal pulse (assuming it appears). If the flyback is defective, one of two waveformsis likely to appear. The first may appear as a sinusoidal waveform with a distinct ringing appearance. Thisdefinitely indicates flyback problems. The second phenomenon will be a horizontal retrace pulse with a second,lower level, “phantom” pulse. It is sometimes normal for this “phantom” pulse to appear at low B+ input levels butit should disappear quickly as you increase AC voltage. Monitor the AC current level closely while doing this. Ifthe phantom pulse remains and current starts to rise, it is time to replace the flyback.

One last situation that might occur is that the retrace pulse looks great but as you approach higher AC input, itbegins to jitter and dance on the scope screen. The current will also be higher than normal. Back off the ACpower quickly as this usually indicates excessive loading on the flyback secondary. Take resistance readings toground looking for shorts. Do not forget to read resistance across any + and – supply rails. The vertical outputIC is notorious for shorting the +15V and –15V rails together which would be missed by static resistancemeasurements to ground

NOTE: Many technicians prefer to “ring” suspected transformers. This is OK and is a good method for detectingshorts in the windings. However, it is not 100% accurate. Problems in transformers sometimes appear under fullvoltage and current load so the above procedure is very effective, although it requires caution and close currentmonitoring. For those of you fortunate enough to own the expensive test equipment to drive and test the flyback,use the equipment in lieu of the above procedures.

High Voltage Shutdown: The only protection for the circuit in this chassis is excessive high voltage. This ismonitored by IC502 as illustrated in Figure 5-1B. Pin 7 is maintained at a constant 8.2V for reference. Pin 6 issupplied with a divided-down sample of heater voltage. This sample voltage should remain slightly below thereference at pin 7. If pin 6 rises above 8.2V, pin 1 will go low and ground pin 43 of the Y/C Jungle IC206. Theinput at pin 43 has two purposes: one is to provide an H pulse sample from the horizontal output stage forhorizontal AFC centering, and the other is to monitor for an external pull-down which tells the IC206 to stop thehorizontal oscillator. The unit will not go into full shutdown. The horizontal and high voltage will cease, but therest of the unit will still be powered up and the timer LED will begin blinking six times.Since the unit has protection for over-voltage on the 135V line, a failure there is unlikely although it would be agood idea to check it anyway. The problem is likely caused by one of the tuning capacitors in the horizontaloutput stage. Their job is to provide a current path to ground for the flyback transformer while the horizontaloutput transistor is off. The impedance is critical to provide enough current to keep the kickback pulse voltagelevel at the proper potential. Otherwise, the kickback pulse will rise dramatically and cause excessive highvoltage. The key to diagnosing this is to observe the H pulse width. It will be much narrower than the normal 11to 12us duration and, although you will not be able to read it directly, the pulse amplitude level will be much higherthan normal.

Pincushion CorrectionAs seen in Figures 5-1A and 5-1B, this circuit is relatively simple in its operation (as there are a small number ofcomponents). It still manages to give technicians a tough time based on the number of requests for technicalassistance. A lack of understanding is possibly the main reason. Here are some proven techniques to quicklylocate the possible cause:

The circuit requires two basic waveforms to operate. The E/W signal supplied by the Y/C Jungle IC301/pin37provides the necessary modulation reference to gradually increase the scan width towards the center of thescreen edges. This waveform is applied to IC502/pin 9. This will be inverted and amplified by Q503 and applied

17


to the horizontal deflection yoke return. One more waveform is required, however. Vertical rate paraboliccorrection cannot be injected directly into the horizontal circuit, which is tuned for 15.75KHZ. The paraboliccorrection must be gated to provide horizontal-rate pulses that can be accepted by the horizontal deflectioncircuit. These correction pulses will vary in amplitude based on where they occur during the vertical paraboliclevel. Two different pincushion symptoms can occur and must be observed. Is the picture stretched with pindistortion or is it pulled in with insufficient width (black hourglass shaped sides)? Paying attention to whichsymptom is present provides excellent information on where to look.

Pincushion Distortion With Excessive Width: Several scenarios can cause this with the most obvious being ashorted pincushion amp. As most technicians check this first, other possibilities will be discussed. As mentionedearlier, it is very important that the parabolic correction waveform be gated at horizontal rate. Check for properH pulse level at IC502/pin11. It should continue onto pin 8. The final check is to see if the waveform at pin 14 issomewhat parabolic in shape (it will not be a clean one), and that it also contains horizontal component. It is alsopossible that IC502 has failed and is saturating Q503. This is the most common failure in this circuit design nextto a shorted pin amp.

Pincushion with Insufficient Width: Loss of vertical parabolic correction will cause this. Check for presence atIC502/pin 9. Check for 10VDC at IC502/pin 14. If not present, change IC502. If present, suspect open Q503,open pincushion modulation transformer, T502 or poor solder connections.

IMPORTANT NOTE: If you have checked and/or replaced everything in the pincushion circuit and you still havethe problem, there is one more component that can cause this: The EEPROM IC004 located on the A board.This has been found to be the source of the problem in several cases where a technician has replaced most orall of the components in the pincushion correction circuit.

Vertical DeflectionNot much has changed in the vertical deflection design over the last few years. Looking at Figure 5-2, the RA-3 still utilizes the traditional vertical output IC utilizing negative feedback from the deflection yoke return tomaintain linear amplification of the drive signal. It is simple and works quite well. You rarely see vertical linearityproblems with this design. As with the pincushion circuit, the vertical circuit seems to cause problems in the fieldand a significant number of calls come in on the tech support line about this.

The one major change in the design on this chassis is the addition of IC1501. It provides shading correction forthe light level changes due to the angle of the outer CRTs and, functions as a “zooming” control for the vertical.This part of the IC monitors flyback current from the ABL circuit at IC1501/pins 7 and 14 and helps to minimizevertical size fluctuations during rapid light to dark transitions of the programming. The addition of this circuitdoes not change the troubleshooting approach much, other than to add an additional path for the vertical signal.

The Y/C Jungle IC206 will output vertical drive regardless of whether output and feedback are operating properly.This makes troubleshooting much easier than it was on circuit designs from many years ago in which the entirevertical circuit was dependent on feedback to even oscillate.

18


Vertical Deflection TroubleshootingNo Vertical Deflection: The first instinct of the technician is to go after the vertical output IC1501 and understandablyso. It is a drive component with heavy current usage and heat dissipation, and it is usually the cause of thefailure. It is almost a given that F651 and/or F652 on the G board will also open. .

The first check that you should perform (and this applies to all Sony televisions of the last seven years) is tocheck the voltage level of the clock and data lines on the I2C bus. They are conveniently labeled SCLK andSDAT. The DC voltage should not be lower than 4.6 volts. If either of these lines is loaded down, the verticaloscillator will not start. This is the number one cause of multiple component replacement for a simple verticalproblem. You should always check the clock and data level whenever you have a strange problem, particularlyif it appears that multiple symptoms are present. Although most television chassis’ will not produce verticaldeflection, some will generate other symptoms. As an example: The AA-2W used in Sony’s KV32/36XBR200sets will display a magenta raster with no video and insufficient vertical height that can easily cause a technicianto look for separate failures and blame the y/C Jungle IC. Assuming the bus is okay, move onto the nextscenario:

51

3

4

39 35

28

40

34

13 12

1

7

14

7

6 8

4

5

32 6

C1522R1528 R1578

R300

R1585

9V

C277 R1533

R1586

CN1301R280SCL

SDP

C288

C1551

R1521

C1513

R1579

R1554

ZR BD

ZG BD

REDDY (V)BLUE

DY (V)

GREENDY (V)

IC1509V OUTSTV9379

L1501

-15V

D1525+15V

C1559

R1570

R1560

C1552R1550

TH1501

L1513R1559

R1549R1552

R1581

R1462

R1461 R1431

R1432

R1402

R1401

A BD

IC1501

IC1501

7 FROMCN506/7

L1502

VP

N

R1583

R1582C1524

D15015.6V

C1557C1528

C1525

R1584

+15V

Q1505V-SEP

CN1508CN801V RET

V DEF

CN1432 CN1401

CN1461

B-

VS IN

IC206Y/C

JUNGLECXA2025ASSAWOSC. V- V+

ABL

R299-5V

R1580

C1511

ABL

X

X

X IC1502 IS A MULTIPLIER

1 13 33 3

1 1

3

2

1

+

-

FIGURE 5-2 - VERTICAL DEFLECTION

V RETV DEF

5.2TVP14 1449 6/17/02

19


Check for V drive out of pins 34 and 35 of the Y/C Jungle IC206. Since this unit shuts down during a verticalfailure, you will have to override by shorting the main relay. Unplug all three CRT sockets when doing this. Itis obvious why this unit shuts down during a vertical failure. If IC206 does not output vertical sawtooth signalsfrom the + and – drives at pins 34 and 35, it is likely at fault. If they are present, continue down the line and makesure they are getting through the zoom IC1501 and into pins 1 and 7 of vertical output IC1509. Check the +15Vand –15V supply rails. If present, you are left with a bad driver IC, open yoke or open connection to the yoke.

Repeat Vertical Output IC Failure: If IC1509 fails immediately upon replacement or soon thereafter; it is usuallythe fault of C1557. This is the boost capacitor. It charges to almost 30VDC during the lower half of the verticalsweep to provide additional voltage to allow the beam to retrace to the top rapidly. When this filter dries out oropens, the output IC will attempt to accomplish the retrace but the negative feedback line will resist the suddenvoltage kickback from the yoke and the –15V drive will cause the IC to draw excessive current. In smallertelevisions, a boost capacitor failure causes slight loss of vertical at the top with some fold-over.

Insufficient Vertical Height: The vertical output IC is receiving improper drive levels or it is unable amplify properly.Due to the nature of the operational amp within IC1509, it is rare for this IC to be the cause. Operationalamplifiers have massive amounts of gain, which is why they need negative feedback to keep them under control.Gain problems are most likely to be caused by improper supply voltage (very rare) or problems in the feedbackline. The feedback line should always be checked with an oscilloscope when height or linearity problems arise.In this chassis, the best point is the top end of the ground return resistors (R1549 and 1552). What shouldnormally be here is approximately 1VPP of vertical rate sawtooth. If there is a problem here, you will observe oneof two things: A significantly larger sawtooth level or horizontal frequency contamination in the sawtooth. A largesawtooth indicates one or more of the ground return resistors, or the thermal compensator TH1501, has opened.The negative feedback of the op amp will respond by reducing gain. If there is a large amount of horizontalcomponent in the feedback, the amp will also reduce gain since the average DC level will be higher at thisfrequency. The vertical deflection yoke windings are right next to the horizontal windings so it is very easy toinduce this into the vertical return. Suspect an open C1552 at this point.

Should the feedback line check OK, you now have a possible input problem. The YC/Jungle can cause this andit is difficult to verify without replacing it. Before changing this expensive, multiple-pin IC, try one more thing. Themain NVM IC can cause this problem even though it is capable of changing the height in the service mode. Trychanging the NVM first. It is less expensive and only has eight legs.

20

6. RA-3/3A Video Process Troubleshooting: T & S Models

Chapter 6 - RA-3/3A Video Process Troubleshooting:T & S Models

Overview

One of the more significant video features introduced in the RA-3 chassis was addition of component video input.This was added to all models from the T series all the way up to the V line. Since DVD and satellite boxes wereoffering this video format, it was a welcomed addition, which took advantage of its better picture quality capabilities.The other new feature, only available on the V line models, was Twin View Picture and Picture. It allowed thecustomer to watch simultaneous, live programming side-by-side. The video paths are slightly different betweenthe S and V lines so they will be covered separately.

What is the advantage of component video? “S” video eliminates chroma cross talk, so this issue is not relevant.The luminance bandwidth of both composite and S video is the same as component, so what exactly is theadvantage? The most common answer would be “Less processing of the chroma”. While this may be true, it hasnothing to do with the one, distinct, advantage. Composite and S video utilize the 3.58 MHZ carrier. Componentdoes not. Although broadcast NTSC is limited to 4.2 MHZ of luminance bandwidth (because of transmissionbandwidth), recording and playback devices are not. VCRs are the exception, however, and their bandwidth isrestricted even further than broadcast because of the modulation required for tape recording. When it comes toDVD and other high-end recording devices, the window opens up significantly.The rule of thumb for resolution on a 4:3 display is 80 lines of horizontal resolution for every megahertz ofbandwidth. Since DVD is capable of over 6MHZ of luminance bandwidth, you can achieve 500+ lines of luminanceresolution. Since chrominance is modulating a 3.58MHZ carrier, the bandwidth must be restricted to 1MHZ (atleast on the I channel) to keep the sidebands from spilling over and covering the entire luminance territory. Eventhough the chroma is interleaved between the luminance scan lines, cross talk still occurs as the luminancefrequency nears the chroma decoder “window”. Component video does not utilize the 3.58 encoding and,therefore, is not restricted to the 1MHZ bandwidth on the chroma signal. Using the 80 lines of resolution perMHZ, you see that a maximum of 80 lines of resolution is available for chroma.

Component video allows us to “open” the chroma bandwidth to 3MHZ, which gives much more vivid color detail,especially at the edges of transitions. The better the display device, the more you will see this difference.

Circuit description and troubleshooting will begin with the lower-end T and S line models and then cover the Vline series. Since video processing tends to follow a predictable path from input to CRT, very basic blockdiagrams will be used to isolate problems. Once the problem has been isolated to a certain area, more detailedblock diagrams will be illustrated. Even more detail, of course, can be found in the service literature.

Video problems can be divided into three distinct categories: 1) No video; 2) Improper Video Level; and 3) VideoDistortion.

S Model Video Troubleshooting

As illustrated in Figure 7-1, the main difference in this model series is the lack of a 3D comb filter, using a glasstype instead. It also utilizes a simple PIP circuit which overlays a second video source on top of the main picture.This box can be moved around the screen and its size can be varied by the user. Since a 3D comb filter is notused, the main video path will not be processed by a decoder circuit. Any S video sources will head directly to theYC/Jungle IC206 after passing through some switches. The switches are necessary in order to toggle thesource of the main (or parent picture) and the sub (child picture) path. Since a component video source isavailable at video 4 input, a YUV controller, IC1901, is utilized to switch the component source directly into theYC/Jungle IC206.

The sub video path does not utilize any type of comb filtering but it does go through a decoding process byIC1902. This is necessary since this path will enter the PIP processor, IC1905 and the 3.58MHZ carrier must beremoved. The block diagram in Figure 7-1 is rather crude but it serves its purpose well as you can get a good

21


IC1601MAINVCHIP

PJEDIC002

SYSCON

IC1702COMBFILTER

CV

C

YIC1101

A/VSWITCH

MONITOR OUT

CV

C

MC

RGB

RGB

RGB

IC1901YUV

CONTROLLERYUVSW

IC1903

YUV YUV YUV

YUV YUV

IC1902SUB DECODER

IC206YCJ

R

G

B

TOCBOARDS

PIPORCOMP.

SYNC TODEFLECTIONPIP

IC1905

MY

YIC301Y SW

UV COMPONENTY

SC SY

OSD

C

M H SYNC

MY

Y

FIGURE 6-1 - S MODELS VIDEO BLOCK

INPUTS

SUB UV

MAIN UV

YUV SW

6.1TVP14 6/26/02

overall view of the video path. More detailed block diagrams will appear towards the end of this section. Theycan also be found in the TVP-10 training manual. The goal at this point is to isolate the area in which the problemexists and since there is a main and sub video path along with OSD, these features can be used to help locatewhere it is occurring.

No Video: Many possibilities can cause this condition. The presence of audio is usually a good diagnostic tool,but the set may be in one of the external input modes so it might not be there for you to hear. You should look forthe initial “must haves” and use the following steps to isolate the cause:

The first check is for the presence of high voltage. You should be able to hear it come on. If it does, the nextconcern is if it is staying on. You could be dealing with a HV shutdown. Fortunately, this chassis will indicate theshutdown by blinking the timer LED blinking in sets of six. Looking for lit filaments in the CRT guns is anotherway to verify high voltage. If high voltage is not being generated, refer to the Chapter 5 dealing with deflectiontroubleshooting in this manual to work on the high voltage circuits.

The next step is to wait at least 15 seconds and observe if the timer LED begins to blink in sequences of five. Ifit does, you have an AKB error. Go to Chapter 27 in this manual that specifically deals with AKB and troubleshootaccordingly.

NOTE: The RA-3 chassis does not blank out the video during an AKB problem, which is unique when comparedto all the others that utilize this feature. There still can be a “no video” condition with an AKB error such as lossof G2 or total RGB output failure from the YC/Jungle.

22


With AKB and high voltage ruled out, the following tests can be performed:

The OSD feature is the first tool. Press the menu button on the remote. If you do not have a remote, presschannel up or down. The idea is to get the main CPU to generate OSD graphics. If no OSD appears, the Y/CJungle IC206 is suspect at this point since OSD has its own path directly into it and it is highly unlikely that boththe OSD and IC206 have simultaneously failed. Anything is possible, so several more checks are necessarybefore making the decision to change IC206. If OSD is present, the next test will be even more important.

Using the remote, engage the PIP feature. If a small box appears (whether or not it has video in it), you can bereasonably certain that the sub video path is OK. This also verifies that the lack of video is not being caused bythe YM input at IC206/pin 12 or the YUVSW input at pin 5. The YM controls the luminance level when thecustomer menu is displayed. It lowers the video level so the menu stands out from the background video. Thisline is normally low and if it is pulled high, all video inside IC206 will blank. The YUVSW is a line that switches thevideo off behind the PIP box since IC206 does the mixing of main and PIP internally. This line is also normallylow and if pulled high, it will kill the video. Both signals can cause this problem and they guarantee an unnecessaryY/C Jungle replacement by the technician.

Assuming the PIP will appear along with the OSD, the main video path is where the problem lies. Try gettingactive video in the PIP box (if you don’t have it already) and see if you can change the input source to the PIP.This helps to verify that the A/V switch, IC1101, is probably OK. From here, it becomes a signal tracing chore. Ifno video is present with an S source, the comb filter is OK. The YC from this source bypasses the comb filter. IfS video is present, troubleshoot the comb filter, IC1702. Watch for distortion or loss of the FSC signal at pin 11of IC1702.

Video Level or Distortion Problems

Distortion in the video signal can be quite troublesome. This is especially true if the distortion is subtle since youmay not be able to see it on the oscilloscope screen. The T and S line models do not digitize the video like thehigher end units, so distortion tends to be caused by either power supply noise or the Y/C Jungle IC. Video levelproblems can happen virtually anywhere.

Distorted Video: Isolating the source of distortion by utilizing some of the video features in the set (the same waydescribed previously for a “no video” condition) is the best way to localize the cause. The rule-of-thumb for videodistortion diagnosis depends on whether or not the distortion is synced with the picture. If it “floats” or movesaround, it is likely coming from an outside source such as power supply or a radiating component. If it is eitherstationary or completely random, it is occurring in the video processing circuits.

Once again, using the OSD is the best way to get an overall idea of where to go. If OSD is not distorted, it is anexcellent indication that the RGB drive path from IC206 is good all the way to the CRT. It also indicates thatIC206 is probably working correctly, although it has not been eliminated as a problem yet. If the customer menuexhibits the same distortion, you will have to work from IC206 forward to the CRT drive circuits. Since the signalis now split into RGB components, it is a given that IC206, B+ sources and the CRT itself could be the cause.

If OSD is clean, the next step is to engage PIP and see what the child picture looks like. If it also suffers from thesame distortion, there is a possibility of power supply noise and IC206 becomes a suspect. The main and subvideo paths enter IC206 at different inputs. Other than power supply noise, it is unlikely that both paths have thesame failure causing the distortion. Check the 5V, 9V and 12V supplies for ripple. If the B+ lines are clean, thenext step would be to check IC206.

Another useful tool is to apply a component signal to the video 4 input. By looking at the block diagram in figure6-1, you can see how this signal path bypasses almost all of the process circuitry.

Incorrect Video Level: One very important item to remember about the RA-3 chassis is that the AKB circuitrydoes not blank the video when a problem occurs in this circuit. You do have the advantage, however, of seeing

23


FIGURE 6-2 - SWITCHING AND COMB FILTER (S MODELS)

8

1

15

41

10

3

17

1243

37

58

Q1102BUFFER

56

MAIN VOUT

YOUT2

YIN2

CIN2

COUT2

SYOUT

SCOUT

MTV V

V1

V2

V3

STV V6

Y1

Y2

Y3

Y4C1

C2

C3

IC1101AV SWITCHCXA2079Q

MAIN Y TO IC1901/19 & 23 YUVCONTROLLER/TVIN+DVD Y

MAIN C TO IC206/64 YCJ/CIN

TO IC1902/30 SUB DECODER/CIN

TO IC1903/1YUV SWITCH/DYIN, IC1902/34 SUB DECODER/YINAND IC1602SUB V CHIP

FSC OUT FROM IC206/57TO J1105 MONITOR OUT

YUV MUTE FROM Q1110

FROM MAIN TUNER

FROM J1102

FROM CN1702/5

FROM J1101

FROM SUB TUNER

S VIDEOINPUTS

Q1701, FL1701Q1702, Q1703

Q1103, 1104BUFFER

15

19

60

24

39

63

COMPONENT Y

S VIDEOINPUTS

34

35

SDA

SCL

CV

IC1702COMB FILTER

TC90A53F

23 25

CKIN

ADIN

YOUTCOUT

41

11

Q1705, FL1703Q1706, Q1709

Q1704, FL1702Q1707, Q1708

45

6.2TVP14 5/22/02

the timer LED flash in sequences of five, which will help steer you in the right direction. A prime example of thisis the failure of Q706, Q733 and Q764 on the CR, CG and CB boards. Figure 6-4 shows the CG board with Q733as an example. These transistors, which are responsible for monitoring cathode current, would short or leak ifthe CRT arced. All three of the transistors are connected to the IK return line via Q734 buffer. If one or more ofthese current monitors failed, the IK return line would be “swamped” with DC voltage. IC206 would now befooled into thinking that insufficient pulses were being fed back and, depending on how much the current detecttransistor was leaking, would generate a overly bright picture. In some cases, that would cause the set to go intoover-current protect. The best way to isolate this problem is to read the collector voltage of each IK monitoringtransistor. Approximately 2VDC should appear there. If one of the transistors is leaking, you will see 5VDC sincethere is a zener diode D736 at Q734B that prevents this line from going any higher. Service Bulletin #443(E08921862) deals with this issue.

NOTE: This failure can be very confusing. If the unit was not going into protect, you will see video in the brightraster and notice that OSD was not being displayed either. Since main video and OSD enter the Y/C Jungle ICat separate inputs, it appears that IC206 is the cause. Many A boards have been be ordered and installed andthe problem would still exist. It is important to remember that on all Sony televisions, the OSD will not functionuntil the unit has completed all initialization routines and this includes the AKB circuit.

If the video level problem is not AKB related (timer LED not flashing), you will have to try to eliminate IC206 as thecause. Again, OSD is a valuable tool. If it is of the correct level, IC206 is probably not the cause. Try using PIPto see if the sub video level is OK. If it is, troubleshoot the main video path. If both sub and main video are toohigh or low, check the voltage at pin 28 of IC206. This is the ABL input and the voltage will fluctuate between 2and 6VDC with 2V on a bright scene and 6V with no video. The ABL line from a flyback transformer is negativegoing and pull up resistors from the 135V supply will be used to keep it at a positive level. These pull up resistorsare known to increase in value and cause the line to go low or even negative. IC206 will react by loweringbrightness significantly since it is trying to protect the flyback transformer.

24


15

144

5

3

122

11109

Q1920V BUFFER

Q1914Y BUFFER

13 1

FROM J1106COMPONENT

INPUT

PB

PR

SY OUT 1FROMIC1101/56

DVD SW 2FROMIC1904/3

VOUTUOUT

YOUT

DVDSW

DV INDYIN

DU IN

V INU INY IN

SUB YTOIC602SUB V CHIP

TO IC1901/6YUV SW.

IC1905 PIP PROCESSOR SDA9288

FIGURE 6-3 - PICTURE IN PICTURE (S MODELS) 6.3TVP14

IC1903YUV SWITCH

BU4053

Q1906SUB C BUFFER

SC OUT 1FROMIC1101/58

Q1916Y

BUFFERY

V

Q1917Y AMP

Q1918BUFFER

SDA

SCL

28

3032

21

12

8

9

722

4

3 YOUT

UOUT

VOUTSDASCL

Y IN

U IN

V INX IN

XQ

SELQ1914

BUFFER

Q1905BUFFER

Q1907BUFFERQ1903

BUFFER

X19023.58MHz

X1901503.5kHz

11

12

13

CVBS/Y INCIN

RY IN

RU IN

RV IN

RY OUT

RU OUT

RV OUT

XNTSC

APCCERA

SDA

SCL

VSYNC

H SYNC

VOUTUOUTYOUT

IC1902SUB

DECODERCXA2019

201918

38

29

26

1

8

7

6

32

3934

37

36

SDA

SCL

TO IC1901/1

TO IC1901/2

UTO IC1901/3

Q1904SUB Y BUFFER

Q1908BUFFER

5/22/02

7

1

3

1

D736

1

FROMFOCUSBLOCK

C732

R732 G2

SG731

Q733

R741

R742

L731

R736R739

+200V

D732

C735

CN731

FROMA BD.CN204

R736

C734

R737R746

Q734

R747

D735

R743

CN732 IkR

IkB

9V

CN737

TO FOCUSBLOCK

C737 R744

CN736

CN735

CN734

TOG BOARDCN503

FIGURE 6-4 - CRT DRIVE (CG)

1

R733Q731R735

R753CLK

C733

D731

Q722

D733 D734

CN733

G

IK

TO CRBOARD CN702

TO CBBOARDCN762

SG7324

1110

9

8

76

5

1F

G1G2

G1kH

H G1 G1

CG BOARD

76

9

97

6

67

6.4TVP14 5/22/02

25


CV

C

Y

COMPONENTY

UV4 UV5

Y/CV

C

MY MY

SY

SC

SUVSY

YUV

YUV

Y

UV COMPONENT YUV OR PIP YUV

YUV

MAINYUV

C

YTOTUBES

R

G

B

OSDRGB

Y

FIGURE 6-5 - V MODELS VIDEO BLOCK

SUB YUV

U BOARD

IC2043D

COMBFILTER

IC1410Y SWINPUTS

IC1704UV

SWITCH

IC1404YUVSW

IC1405P & P

IC1407YUV

CONTROLLER

IC1702A/V

SWITCH

IC1403SUB

DECODER

IC1402MAIN

DECODER

IC1206YCJ

PJED

IC1601VCHIP

IC002SYSCON

IC1405Y SW

MAIN C

UV

Y

YUV

6.5TVP14 6/26/02

FROM B BOARD

V Model Video Troubleshooting

These models have several additional features not found on the lower-end sets. A 3D comb filter provides higherquality cross-talk separation along with noise reduction circuitry for the Y component. This is why the S videoinputs are routed through the comb filter. Only the component inputs will bypass this circuit. A decoder circuithas also been added to the main video path after it exits the comb filter since it is going to be routed to a Pictureand Picture processing IC along with direct input to Y/C Jungle IC206. This will provide twin picture viewing in aside-by-side fashion rather than a main picture with a small inset box. There is also an additional componentsource available at the video 5 input. Figure 6-5 illustrates the basic paths of the main and sub video andprovides the key source for isolating video problems. Figures 6-6 and 6-7 illustrate block diagrams with moredetail to aid in isolating problems.

No Video

As the initial steps mentioned in the previous section dealing with the T and S models, loss of high voltage andAKB errors must be ruled out. If either one of these has failed, refer to Chapter 5 for high voltage and Chapter27 for AKB troubleshooting

Checking for OSD should still be your first check. If it is present, you can tell if the RGB output path from IC206all the way to the CRT is OK and if IC206 is probably working correctly. If no OSD is present, you will need towork from IC206 forward (assuming the OSD circuit has not failed, but it is highly unlikely that both OSD andvideo processing has failed simultaneously).

Using the twin picture feature will be of great help at this point. This is where the video processing differs fromthe T and S models. Although the YC from the 3D comb filter and the component video path are routed directlyinto IC206, the P&P processor, IC1405, handles the mixing and insertion of the main and sub video paths for twin

26


view video where it is inserted into the Y/C Jungle into a separate port. By engaging this function, you can get agood idea of where the video loss is occurring. When the twin boxes appear, the main video source will bedisplayed in the right box and the sub video in the left. What you will observe is one of three possible conditions:Video in the right and left boxes, video only in the left box or no video in either box.

Video Appears in Both Boxes: This indicates that the main and sub video processing paths are functioning andthat IC206 is OK since the P&P video Y is switched into IC206 at the same point where normal video would enter.YUV controller IC1407 is responsible for toggling between main and P&P luminance so this is the area totroubleshoot. Either IC1407 is not switching in the main video or P&P controller IC1405 has IC1407 stuck in P&Pmode. Check pin 6 of IC1407 for 2.7VDC. If it is at 5VDC, troubleshoot the line to see what is pulling it up.

Video Appears in Left Box Only: There is a problem in the main video path. Since there are several sections, onequick way to isolate the condition is to apply component signal to the video 4 or 5 input. This causes the Y signalto bypass the A/D converter (IC203), 3D comb filter (IC204) and main decoder IC1402. Y switch IC1410 willroute the component Y directly to IC1407. If component video appears, troubleshoot the circuits listed abovethat were bypassed. If component video does not appear, suspect AV switch IC1702 or YUV controller IC1407.

No Video in Either Box or No Boxes: The presence of boxes is a good indicator that P&P IC1405 is able togenerate the necessary switching and box borders, and that the IC1407 is able to send them to the Y/C Jungle.Since the original problem was no main video and the P&P controller gets both main and sub video, the only arealeft that is common to both video paths is the A/V switch IC1702. It has failed or cannot function because ofmissing voltages, or the microprocessor IC002 cannot communicate with it.

If no P&P boxes are present, IC1407 may be incapable of passing any video or IC206 is suspect. Isolate theproblem by checking for video at pins 1, 2 and 3 of IC206.

Video Level or Distortion Problems

Methods for isolating video level or distortion is similar to the approaches used for the T and S models. Distortionis more likely to appear in this design due to the A/D converter and 3D comb filter. Utilizing the P&P feature anddirect component inputs will assist in isolating the problem and are much in the same way as finding a no videocondition.

27


Q211, 214BUFFER

FL202,Q203, 207

B.P.F.

Q201, 204INVERTER

1413

27

28

29

2 31

5 34

7 36

10 39

6

24

4

11

12

10

98

76

60

59

61

75

Q228BUFFER

Q226, 227PEEKING

Q1403BUFFER

50 83

5

22

20

17

13

67

74

28

13

16

19

22

26

9

2

99

TO IC1402/32 MAIN DECODER/C IN

TO IC206/64YCJ/C IN

IC1410Y

SWITCH

FROM UBOARDCN1701

CN401

MAIN C

MAIN Y

IC2043D

COMBFILTER

uPC64O81

MRAS

X1

AYO

MAO

MA8

WEOELCAS

UCASSDA

SCL

SDA

SCL

RAS

I01

I016

VIN

DB1

DB8

CLKPCL

ALTESTO

CSI

IC203A/D

CONVERTERuPC659

DYC02

DYC09

MIO0

MIO15

AO

A8

IC202 4MB EDOMSM514265C

TOIC1402/34CVBS/Y IN

FSCOUTFROMIC206/57YCJ

KILLERFROMIC002/30

CN201

FSC1 ACO84

3

1

72

Q210BUFFER

FL203,Q215,

216B.P.F.

Q206,212BUFFER

30

FL201,Q202,208B.P.F

Q209, 213BUFFER

COMB CTO CN1703U BOARD

D BOARD

Q210BUFFER

MAIN V/Y

MAIN C

18

16

FIGURE 6-6 - COMB FILTER (V MODELS) 6.6TVP14 5/22/02

28


FIGURE 6-7 - VIDEO PROCESSING (V MODELS)

Q220BUFFER

DY FROM IC1405/86

P+P/DFB FROMIC1405/ 93

Q219BUFFER

Q218BUFFER

TO CGBOARDCN731

CN003CHECKCONNECTOR

FSC1TO IC204/50COMB FILTER

TOV CHIP

SDA

SCL

MAIN CFROM IC1702/58

DU FROM IC1405/90

DV FROM IC1405/88

MAIN U FROMCN401/3

MAIN V FROMCN401/1

MAIN Y FROMQ1402

MAIN Y SW.FROM IC1409/7

FULL DVDFROM IC1409/1

COLOR FROM IC1409/5

HUE FROM IC1409/6

CN204

Q1422YUVSW

6.7TVP14 5/22/02

A BOARD

Q1418BUFFER

Q1420BUFFER

Q1419BUFFER

Q1403 SYNCBUFFER

23

19

13

18

6

8

9

P-Y

12

5

PB-Y

PR-Y

DVD B-Y

DVD R-Y

DVD Y

TV IN

DL YSW

YSW

COLOR

HUE

YOUT

RYOUT

BYOUT

TVOUT

CLAMP

IC1407YUV CONT.

CXA2039

16

17

1

3

2

22

21

X202

57

63

55

4

3

27

BGP

SDA

SCL

Y INIKIN

IC206YCJ

CXA2147

FSCOUT

59

5

YUVSW

7

8

64

10

20

24

26

EY IN

ERY IN

EBY IN

C IN

ROUT

GOUT

BOUT

Q1424TV BUFFER

Q1414, 1416LEVEL SHIFT

10

9

7

5

1

67

29

1. Features

Chapter 7 - Troubleshooting the RA-4 Chassis

OverviewThe RA-4 chassis represented a great leap forward for Sony in the rear projection television market. One of itsmost outstanding introductory features was the ability to perform line doubling of the standard 480i NTSC scanrate. By doubling the scan horizontal scan rate to 960i, the annoying scan lines that were prevalent on theselarge-screen sets were virtually eliminated. Not only is this chassis able to double the scan lines, but it alsodoubled the horizontal resolution by utilizing a new circuit known as the “Digital Reality Creator” or DRCTM. Thisnew circuit eliminated the “aliasing” that occurs when normal scan lines are simply doubled by making use ofpattern recognition technology to smooth out the jagged edges that would normally occur. This set was capableof producing “near high definition” quality from NTSC video sources. Unfortunately, this chassis was only availablein two models (KP53/61XBR200) and these were relatively high-priced units, but it would set the precedent forfuture designs.

The RA-4 was also the first chassis to introduce a fully digitally controlled convergence circuit, which allowed forconventional adjustment methods via the remote control to allow the technician to perform “fine” touchupadjustments at specific areas of the screen to provide excellent geometry and convergence control throughoutthe entire screen area. These adjustments could then be written to memory and, by using special sensorslocated behind the front bezel, allowed the customer to press a button and bring the convergence back to properalignment. This feature is known as Flash FocusTM.

The picture-and-picture circuitry also received an upgrade, allowing the customer to scale the size of the mainand sub picture with the remote control. Channel previewing was another feature that would allow the customerto view active channels around the perimeter of the main picture. This would be handled by a new circuit knownas the “multi-Image driver” circuit or MIDTM. With these new features added, the video processing became morecomplex and practical methods are necessary to help isolate a failure.

This chassis also introduced an entirely new power supply design that deviated from the previous style. The dualswitching transistor design requiring the need for feedback was replaced with a new type that would functionmore like a PWM supply, although frequency shifting would still be the core of the regulation concept. Thisrequires different troubleshooting approaches but the procedure is considerably easier.

The RA-4A would soon follow and, although it carried over the many of the new concepts of the RA-4 chassis, itintroduced a “high definition ready” version of the chassis that will be covered in another section.

30


Chapter 8 - RA-4/4A Power Supply Troubleshooting

Overview

The RA-4 chassis introduced a new, simpler, standby power supply. Major design changes occurred in the mainpower supply. An oscillator circuit was now being employed that was independent of the output stages. Thisoscillator provided the necessary drive signal to two, independent, driver circuits that shared the distribution ofpower requirements for the set. The method of controlling the main power relay is different from past designsand regulation no longer relied on the use of a control winding in what was known as the Power RegulatingTransformer (PRT). Oscillator frequency changes are controlled directly by an IC that monitors a secondaryvoltage feedback. For a more detailed description of this circuit, refer to the TVP-08 training manual (P/NTVP080299).

Standby Power Supply TroubleshootingIn order to understand and effectively troubleshoot this circuit, it is necessary to view the AC input circuit alongwith the standby supply and these are shown in Figures 8-1 and 8-2. Along with a main power relay, RY6001,there is also an inrush current relay, RY6002. It is important to know what this relay does to assist in protect circuittroubleshooting which will be covered later.

The negative side of the bridge rectifier, D6002, is connected to hot ground via R6010. This 2.2Ω, 10 wattresistor will limit the initial current surge at startup and will be shunted by RY6002 as soon as the +15V line fromthe main secondary comes up. This happens very fast (less than a half second) after the main relay energizes.RY6002 is protected against failure by monitoring the voltage at pin 4 of D6002. If the relay does not shuntR6010 within five seconds, C6013 at the base of Q6004 will charge and cause the collector to go low and stopthe main power supply oscillator. The main relay will remain engaged.

The standby supply consists of T6003 and IC6001 as the main components to provide oscillation. Pin 5 ofIC6001 will provide the current return through the primary to ground. Unregulated B+ is provided by D6001 andD6003 through fusible resistor R6012. The circuit is self-oscillating at this point. Voltage regulation will beachieved by monitoring the feedback line from T6003/pin 4 through the rectifiers and charging C6014. This willprovide an average DC level to monitor and control the oscillator frequency. Notice the voltage tap betweenD6012 and 6015. Approximately 15VDC occurs here to provide voltage for the main relay, RY6001 and the VCCswitch circuit. Pin 7 of T6003 will provide 7.5VDC for the 5V regulator IC6104 to power the main microprocessorand other various circuits needed for standby operation.

Failures in the standby will usually cause a completely “dead” set. There will be no relay clicks heard and notimer LED flashing on the front panel. It is simply a matter of checking for input voltage at IC6104 and, if present,5VDC at the output. If input voltage to IC6104 is not there, verify the oscillator circuit is running. As mentionedearlier, this oscillator is not dependent on feedback to run and does not require a start circuit. As long as B+ ispresent at T6003 primary and pin 5 of IC6001, the likely defective components are IC6001 or the protect circuitcomponents consisting of D6005, D6006, C6015 and R6004.

31


FIGURE 8-1 - AC INPUT & SWITCHING B+

AC(W)

AC(L)

CN6004 SPARKGAP

R6001

R6002C6001

F600110A

TO IC6003/2E AMP-(IF LOW,OSCILLATORSHUTS OFF

Q6004

C601310uF

R6022D6032

R6017

SPARKGAPS

L6001

C6002

C6004

D6007

R6014 R60102.2OHM10W

D6009

RY6002INRUSHCURRENTRELAY

C6006

R6013

C6012 C6007

L6002

VD6001

FROMVCC

RY6001POWERRELAY

D6002

R6006

C6004

C6008

G BOARD

C6010

C6011

FROM+15V

F60026.3A

L6003SWITCHINGB+

DCTO SOFTSTARTPROTECTIONQ6002

ACTO STANDBYSUPPLYD6001

1

2

4 3

2 1 2 1

4 3

3

4

1

2

R6031 N

3

4

2

1

8.1TVP14 6/26/02

IC6001TOP209

PWMSW

G BOARD

FIGURE 8-2 - STANDBY SUPPLY

ACFROML6002/3

TO VCCSWITCHFOR ACOCPQ6013/B

D6001

D6003C6006

R6012

D6006P6KE200

D6005

5 4

8 1

2

3

HOTGND

R6004

R6021

D6011MTZK9.1A

C6014

C6017

D6012 D6015

C6015

2

1

4

3

5

7

T6003SRT

C6136

D6120

C6317

C6138

L6113

15V TO Q6011/E VCC SWIC6002/9 DRIVERVCC SOURCEVOLTAGE

1

3

2

IC6104BA05T

RM+5V

1

TO SYSCONA BD.CN505/2

CN6101

C6145

TO Q6102LATCHTOIC6102OVP/OCP

TO IC6011VCC SWITCH

8.2TVP14 7/11/02

32


FIGURE 8-3 - VCC SWITCH

STANDBYSOURCEVOLTAGEFROM D6003/K

R6043

R6042

D6035RD12ESB2

C6037 R6040

Q6012

P

FROMD6015/KVCCSOURCE R6018

R6039

Q6013

C6036

D6034

R6019

Q6011VCC SW P

R6041

Q6001

D6033

TO R6023 VCC& R6016SOFT START

TO IC6003 OSC

TO IC6002DRIVER

TO IC6004 DRIVER

TO RY6001POWER RELAY

TO D6010SOFT STARTRESET

SLINK

ST 5V A BOARD

IC1008MAIN CPUCX98585X-XXX

IRMCN

KEY 00 RELAY

CN505 R6112

CN6101

D6111

R6121 D6112

R6125

R6126

NQ6104

IC6011

FROM IC6104/2STANDBY +5V

FROM Q6103/CLATCH

G BOARD

64

14

23

40

41 44

56

4 3

2 13 3

8.3TVP14 7/17/02

FROMQ6005

D6031

R6020

VCC Switching

This circuit is responsible for supplying power to the main relay along with the main oscillator and power switchingcircuits. It is quite different from conventional designs used in previous models. In Figure 8-3, it is shown thatrather than using the relay high command from the CPU to directly control a relay drive transistor, an optical-isolator, IC6011, is turned on by Q6104. A ground return will be provided to Q6001-E, turning on Q6011. Thistransistor will provide power to the above circuits, which includes direct power to the main relay, which is tied toground. Notice the latch circuit consisting of Q6012 and Q6013. This is not the same latch circuit that would putthe unit into conventional protect mode. It is only activated if the unregulated B+ for the standby supply risesabove an acceptable level, which is monitored by the divider network R6042 and R6043 along with D6035. Avariac with the capability to output 150AC was unable to trip this circuit so it is assumed that it is there to preventaccidental application of 220VAC to the unit.

Main Power Supply Troubleshooting

The main supply consists of five major components. IC6003 is an oscillator circuit and will provide square waveout of pins 9 and 10. These 50/50 duty cycle signals will be 180 degrees out-of-phase and will be applied toIC6002 and IC6004. Two independent switching circuits consisting of FET drivers and transformers will supplythe television with the necessary voltages for operation.

In Figure 8-4, the oscillator section is shown. Like the standby oscillator, IC6001, this IC will oscillate without theneed for feedback. As long as unregulated B+ is present at pin 12 and the IC is not being told to stop, it will runand output the necessary square waves at pins 9 and 10. The oscillator will stop running if pin 2 is pulled low bythe inrush current relay monitoring circuit.

33


G BOARD

FROM Q6011/CVCC SW.

FROM IC6005/4REGULATION

FROMIC6011/3VCC SW.

D6010

R6020

LOW B+ PROTECTFROM D6002.3SWITCHING B+

R6008

R6007

D6004MTZJ - 12B

R6011

Q6002

N

R6015

R6016

Q6005SOFTSTART

R6023

D6014

Q6006

D6023

Q6003

NC6027

P

R6028 D6024

R6033

C6028

R6032

D6033

R6034

R6029 R6031

SQUARE WAVETO IC6002/12IC6004/10

SQUARE WAVETO IC6002/10IC6004/12

FROM Q6004INRUSHCURRENTLIMITER RELAYPROTECT

RT C1 VCC C2E2

GND

C

DTC

E AMP1

DPC

REF OUT+

E AMP2-

E AMP-

E1C60162 2uF

P

8 12 11

10

9

21514131

4

5

7

6

IC6003OSCILLATOR

IR3M02

FIGURE 8-4 - OSCILLATOR & SOFT START 8.5TVP14 6/26/02

Regulation is provided by varying the operating frequency based on the error amp input at IC6003/pin 1. Initialsoft start is provided by keeping Q6006 on for about three seconds at turn on due to C6016 charging. This willpull down the regulation error loop and cause the IC to run at high frequency while the secondary voltages arecharging their filter capacitors. The only purpose of Q6005 is to discharge C6016 when the unit is turned off.Should the unregulated B+ drop approximately 20%, Q6002 will turn off when zener D6004 releases, allowingQ6003 to turn on and lock the oscillator into soft start. This is done to protect the switching transistors fromoverheating since they will now have to maintain secondary voltages at a lower frequency. Higher current will beneeded and they will eventually fail.

Referring to Figure 8-5, IC 6002 and 6004 receive the square waves from IC6003 and utilize them to drive theswitching transistors Q6007, Q6008, Q6009 and Q6010. These transistors work in pairs to send current in bothdirections through the primaries of T6001 and T6002. As an example: When pin 7 of IC6002 goes high, pin 1 ofIC6004 will also be high. Current will now flow from Q6008 through C6022 into the primary of T6002 and followa parallel path to C6023 into T601 primary. The ground return path will be provided by Q6009. The processreverses with Q6010 and Q6007 working together to reverse current.

The RA-4 chassis is protected using several circuits for over-voltage and over-current conditions and these willbe covered later in Chapter 9. The following troubleshooting procedures will assume that no protection eventhas occurred causing the timer LED to blink in diagnostic sequences, and the set is not completely dead asdescribed in the previous section on the standby supply.

NOTE: One item to remember is that the FET transistors used in this circuit are very rugged and if they haveshorted, the possibility is high that transients entered the AC line or there may be a high current short, particularlyin the 135V line.

34


FIGURE 8-5 - CONVERTER

FROM SWITCHING B+

FROM VCC SOURCED6015/KFROM IC6003/9

E1 OSCILLATOR

FROM IC6003/10

E2 OSCILLATOR

D6031VCC+12V

VDD

HIN

LIN

SD

VSS

GND

HO

VB

VS

LO

VCC

IC6002DRIVERIR2112

VDD

HIN

LIN

SD

VSS

GND

HO

VB

VS

LO

VCCIC6004DRIVERIR2112

F6002

C6019

C6020

D6016

C6018

C6021

C6030

C6032

D6025

C2029

C6037

D6026MTZJ-20C

FB6003

D6028MTZJ-20C

FB6002 R6025

D6019MTZJ-20C

D6022MTZJ-20C

FB6001 R6024

D6017MTZJ-20C

D6021MTZJ-20C

FB6004

D6021MTZJ-20C

R6035

R6026

Q6009

D6030MTZJ-20C

R6036

R6038

Q6010

SWITCHING B+

R6026

Q6007

R6027

Q6008

C6026

C6025 C6022

C6034

C6033

C6023

SWITCHING B+

T6002 PIT

T6001 PIT

8.5TVP14 5/22/02

9

10

12

11

13

2

7

6

5

1

3

9

10

12

11

13

2

7

6

5

1

3

4

2

8

10

12

1

3

12

10

11

15

13

14

18

16

17

8

7

9

Unit Will Not Power Up

Look at the timer LED. If it is blinking once a second, the standby supply is working. The main and inrush currentrelays will now become an important tool in deciding where to go next.

No relay clicks heard: There should be two, distinct, rapid clicks heard. If none are heard, troubleshoot the circuitstarting from the relay high command from the CPU through the VCC switch circuitry and even the main relayitself. Refer to Figure 8-3 to troubleshoot this circuit.

Relay clicks once: If a relay click is heard, it is very important to listen carefully for two rapid clicks. They shouldbe less the one-half of a second apart. This verifies the inrush current relay is engaging. If only one, and not two,rapid clicks are heard, the unit will power up for a short period and then the oscillator will stop. The main relay willstill be engaged and there will be no other indicators as to what is wrong. This is the symptom of the inrush relayprotection. Check for a defective relay or loss of 14V supplied by Q6106 on the 16.5V line on the secondary ofT6001. One might think that a failure of the oscillator circuit could cause this symptom but several of thesecondary voltages are monitored by the protect circuits and the relay click sequence will differ as shown next.It is very important to verify this test as it can lead the technician to the wrong areas.

Two rapid relay clicks: The presence of the two clicks indicates the power supply is oscillating. One item that canproduce the symptom of a dead set is the loss of 12V from IC501 on the A board. This would prevent thehorizontal oscillator from running and may mimic the symptom of a dead unit.

35


Two rapid relay clicks followed by a third click one to three seconds later: If this condition occurs, the unit is goinginto protect mode. The timer LED may assist you on this problem as this unit utilizes self-diagnostics althoughnot all protect lines are monitored. In this case, go to Chapter 9 for troubleshooting the protect circuits.

Shorted Switching Transistors

The greatest concern in this situation is what caused them to short. One important clue to watch for is whetherall four have failed. Since only two are on at any time, a failure of all four is a warning sign that transients mayhave caused the failure. It could have been caused by other areas but line transient damage is likely to havedamaged more than just the transistors. Since the switching transistors are not biased in an AB class likeprevious supplies, they are easier to troubleshoot.

Jumping the main relay and applying low AC voltage with a variac does not work well in this power supply design.It will not start oscillating until 70VAC or more is applied. Since the soft-start circuit limits initial current by up to50% and the FET drivers are able to withstand large current surges, direct shorts on any of the secondary lineswill not cause them to short. The supply will attempt to start and then the unit will go into over-current protectbefore they can be damaged. Starting the unit with full AC power and observing for shutdown is necessary whilewatching the initial AC current draw. This chassis operates at current levels of approximately 800ma, dependingon the AC voltage level.

Excessive current: In this case, the unit will shut down and AC current will peak at 2A or more. Something is stillwrong. Since it is natural for technicians to always check for shorts on secondary lines, the excessive load isprobably dynamic or, although remotely possible, one or more of the switching transistors are on when theyshould not be. It gets down to disconnecting secondary lines at this point starting with the 135V being the mostlikely cause. Do not forget to take resistance readings across the ± rails. Do not lift components on the 135V linelocated before L6106. This will open the regulation loop and cause the supply to output maximum voltages.

If lifting secondary lines does not get rid of the problem, the cause is a short in one of the two transformers or oneof the driver ICs (IC6002/6004) is the cause. An effective way to test the drive and oscillator IC circuits is todisconnect the drive signals to the gates of the switching transistors and short VCC switch Q6011 (not the mainrelay). This will run IC6003, IC6002 and IC6004. Connect a dual trace scope to pins 1 and 7 of each of the driveICs and verify that square wave pulses are present and are 180 degrees out-of-phase with no overlap in timing.If there are no pulses, look for DC voltage. If either of the above conditions is present, the problem has beenfound. If both drive ICs have overlap or no pulses with DC, check IC6003 pins 9 and 10. If they have overlap oroutput DC, troubleshoot the oscillator.

Very little or no current: The power supply is not running. This is a scenario likely to be encountered if theswitching transistors have been damaged from line transients. The gates of the transistors are very high impedanceand the transient has probably damaged one or more of the protect components. Notice the number of protectdiodes in this area. Leave the new switching transistors disconnected from the drive signals and short VCCswitch Q6011. The oscillator and drive ICs can now be serviced starting with the IC6003 and moving forward.

Regulator Troubleshooting

As illustrated in Figure 8-6, the regulator stage is quite simple in design. IC1601 monitors the 135V line. It actsas an inverter so any rise in the B+ will cause the output to go lower and vise-versa. Controlling the brightnessof the LED inside the photo-optical coupler will vary the DC voltage at pin 1 and 6 of IC6003. The more thevoltage is pulled down, the higher the frequency the oscillator will run.

Excessive B+: This will cause the set to shut down and flash the timer LED in sequences of three. One way toquickly isolate the cause is to short pin 2 of IC1601 to ground. Under normal conditions, this will cause the B+level to drop dramatically. This is a quick way to verify that IC6005 and IC6003 are functioning properly and this

36


FIGURE 8-6 - REGULATION

FROMQ6006/ESOFTSTART

11V

135VV OUTSENSE

IC6101VCC CONTROLLERSE135N

COLLECTOR R6128IC6005VCC OUTPC123FY2

R6028 D6023

D6024

R6033

R6029

C6027

EAMP1-

E AMP2-

REF OUT

DPC

E1

E2IC6003OSCILLATORIR3M02

TOCONVERTERDRIVERIC6002 &IC6004

1

3

2

1

2

4

3

1

6 RT

15

14

13

9

10

G BOARD

8.6TVP14 6/18/02

is the most common result obtained. IC1601 and its connection to the 135V line are the next check. The mostcommon cause of excessive B+ is an open or increase in value of the resistor connecting the 135V to IC1601(R6115 in this chassis).

If shorting pin 2 of IC1601 does not stop the over-voltage problem, short pin 4 of IC6005. If the voltage nowdrops, replace IC6005. If it still does not drop, IC6003 or one of the input components may be open.

Low B+: Check the voltage at IC6005, pin 1 and 2. There should be at least .6VDC difference with pin 2 being thelowest. If there is, the optical isolator is being told to increase the frequency. If there is little or no voltagepotential across pins 1 and 2, disconnect pin 4 of IC6005. Turn the unit on and it should go into over-voltageshutdown. If B+ is still low, check components at error input of IC6003 and if OK, replace the IC.

37

9. RA-4/4A Protect Circuit Troubleshooting

Chapter 9 - RA-4/4A Protect Circuit TroubleshootingOverview

The protect circuits in the RA-4 chassis contain several additional sections of monitoring than the RA-3. Thehigh voltage and horizontal deflection circuits are separate, so monitoring deflection loss is necessary. Severalmore low voltage lines are also monitored. The self-diagnostics feature will assist in isolating a particular circuit,but not all of the monitored lines are sensed by this feature. Below is an example of the diagnostics page whichis entered by pressing “DISPLAY”, “5”, “VOL –”, and “POWER”.

Self Check

2: +B OCP 00

3: +B OVP 00

4: V Stop 00

5: AKB 00

6: H Stop 00

7. HV 00

8: Audio 00

101: WDT 00

The numbers on the left indicate how many times the timer LED flashed, which designates the probable cause ofthe shutdown. The flashes on the LED will occur at one second intervals, followed by a three second separationperiod and repeat again. The numbers at the extreme right indicate how many times the problem occurred up to99 events. You can see why this is beneficial for intermittent troubleshooting. It is always a good idea to clear theevents before exiting and that can be done by pressing “8” “enter” on the remote. This is not the same aspressing these buttons in the service mode. It will only clear the events and not reset customer defaults. Bewarethat the service manual instructs you to enter the service mode to clear these and that is a mistake. You can doit right from this screen. Let us briefly cover each one.

+B OCP: Excessive current on the 135V line. This is usually caused by flyback problems or secondary loads onthe line. The circuit could also be tripping for no reason. This is why you should always monitor AC current whilethe unit is shutting down. It will help you to know if you are really dealing with an over-current condition and youcan then be more cautious in troubleshooting.

+B OVP: The 135V line has exceeded 139 volts. Go back to the Chapter 8 on troubleshooting regulator problems.

V Stop: The vertical deflection circuit has stopped operating. This indication can also occur if the high voltagecircuit fails since it provides the +15 and -15 volt supply rail to the vertical output. Loads on the I2C data and clockbus can also be the source of this problem.

AKB: One or more CRT cathodes are unable to generate sufficient current to return a good feedback pulse. TheAKB detect circuit may also have failed. It is common to see multiple events in this diagnostic feature along withregistered HV failures. See the special section in Chapter 27 on AKB at the end of this manual.

H Stop: Horizontal deflection has failed. Since the unit has a separate high voltage circuit, the set will shut downto protect the CRTs. This will be covered in Chapter 10, which deals with the deflection circuits.

HV: High voltage has risen to unacceptable levels or excessive current is being drawn in the flyback transformer.

38


IC007MAINNVM

IC6102OVP OCPuP393C

RM +5V+135V

T601/7

11V+22V+19V+15V+7V

R6118

MA BOARD

Q101LVP

+5VD3102

CN3101

CN514

OTMRED

IC1008MAIN CPUCXP85848-016Q

SDA

SCL

ONVMWE

10SDAT 10SCLK

8

5

21

7

6 6

6

48

50

55

4947IC511VIDEOPROC.

CXA2101AQ

56

55

75

6

66

66

55

66

7 13

50

48 6

5

4

3

WP

B+OVP B+OCPIC1009OSD CPUCXP85340A-2560 HV PROT.

H PROT.

V PROT.

A PROT.

SCL

SDA

A BOARD

R1116

R1113

R1107

R1104

D1005

D1007

D1006

FROM HV PROTECTD8021/K D BD.FROM H PROTECTQ5006/C D BD.FROM V PROTECTQ5005/C D BD.FROM A PROTECTQ2610/C K BD.

CN505

CN6101 TOD6002

D6123

D6124 LATCHQ6102Q6103

VCC SW.CIRCUIT

1

2

4 3

RY6001

ACLINE

G BOARD

FIGURE 9-1 - PROTECTION BLOCK 9.1TVP14 5/23/02

Audio: DC voltage has been detected on one or both of the audio out lines. The set is shut down to protect thespeakers. This is usually caused by shorted audio amp IC406.


Protection Circuits Not Covered By Self-Diagnostics

The block diagram shown in Figure 9-1 illustrates an overall view of the circuits that are monitored. Notice thatall of the protect items that appear on the diagnostic screen are connected to IC109 along with routing to therelay latch transistors. If a problem develops on any of these lines, IC1009 will communicate this information tothe main CPU, IC1008 and the failure written to NVM along with the appropriate flash sequence of the timer LED.

39


3

1

2

3

4

12

6

5

8

7

G BOARD

3 4

2 1

5

6

4

3

FROM RM+5V

D6101

FROM+135V

R6102

IC6103REF. VOLTAGEuPC1093J-1T

C6103

R6103

R6101R6104

FROMT6001/7

R6118

+19V

+22V

+7V

R6110

R6106

R6105

D6121

MTZJ - 7.5B R6132

D6125

D6122

R6133

C6140

C6108

2.25V

2.4V

0.2V

C6102

OCP

IC6102OVP/OCPuPC393C

OVP

11.5V Q6101

D6123

P

R6142

R6143

D6124

R6113

R6134

R6120

11.5V

C61115

Q6103

N

CN6101

B+OVPB+OCPPROTECTRELAY

TOA BD.CN505

R6112

R6121

Q6104

D6112

D6111R6125

N

PQ6102

R6117

R6126

IC6011VCC SW.PC123FY2

TOVCC SW.TOSOFTSTART

FROM11V

FIGURE 9-2 - DC PROTECTION 9.2TVP14 5/23/02

The other lines monitored are not detected by IC1009 and, therefore, will not be indicated by the self-diagnostics.Figure 9-2 provides a detailed view of these. This includes over-current (or loss of) the +19, +22 and +7 voltlines. The 11V is protected against over-voltage. The base of Q6101 is kept high by the 11V line through R6133.If the +19V or +22V drops below 11.5V, diodes D6122 and D6125 will forward bias, pulling Q6101 base down andturning it on. This will activate the relay latch circuit (Q6102 and Q6103). The same will occur if the +7V is lostby causing D6121 to fire. If the +11V line rises to 15.1V or more, D6121 will also participate by firing and holdingthe base of Q6101 steady while the emitter rises. This will also turn on Q6101 and the latch circuit.

Most protect circuits that monitor multiple lines are arranged in this manner. Troubleshooting consists of checkingthe voltages across the blocking diodes. Since they are normally reverse biased, the voltages across them willbe greater than .6V. Even a DVM without peak hold can detect this. For example: If the +19V failed, the meterwould read a maximum of 0.6V across D6122. Under normal conditions, approximately 8.5V would appear. Bymonitoring blocking diodes for 0.6V and zener diodes for their rated voltages, one can test each of these whileturning the set on and quickly locate the source of the protection event.

Another useful tip when working on shutdown events is to monitor the AC current draw with the variac. Largecurrent spikes will assist in determining if an over-current condition exists, and helps to decide which areas tocheck first. When working on direct-view televisions, be sure and disconnect the degauss coils to get an accurateassessment since they draw large amounts of current. Even if the diagnostic feature is indicating an over-current protection, it is wise to check the AC current draw when turning the set on. This helps to determine ifthere is an actual current problem. Sometimes the circuits that monitor the current will fail and cause a shutdownevent even though one does not exist. The block diagrams illustrated in this manual will assist in locatingshutdown sources within minutes.

40

10. RA-4/4A Deflection Circuit Troubleshooting

Chapter 10 - RA-4/4A Deflection Circuit Troubleshooting

A BOARD

1

10

11

12

8

9

7

6

5

3

2

4

8

9

FROMIC516/7HS BUFFER

+12V +12V

C553

R545

C523

C543

C546

R550

C548

R537

C521 C522

R549

R536

R540

R548 R552

R562

C558 R577

HSIN

VCCHDDUTY

H DRIVE

H OSC 1

H OSC 2IC507

H JUNGLELA7856

FBPINAFC

FILTER 2

FILTER 1PHASE 1

PHASE 2

C550

R590

R591

R586

C571

Q514N

R618

R532

R516 R541

R534

C525 C526

FROM IC512/24AFC VDSP

TO DBOARDCN5004

CN509

FIGURE 10-1 - HORIZONTAL JUNGLE 10.1TVP14 5/24/02

Overview

With the introduction of scan line doubling, the RA-4 chassis introduced new circuit designs. The horizontal scanrate operates at 31.5KHZ instead of the conventional 15.75KHZ. The YC/Jungle IC is replaced by a separatevideo process (IC511) and a horizontal jungle (IC507). High voltage is developed in a separate circuit and will becovered in Chapter 11. The vertical deflection circuit has had some notable changes, such as its own digitaldeflection generator. The output stage remains relatively unchanged.

Horizontal Deflection

Figure 10-1 illustrates how horizontal scan is developed. IC507 is solely dedicated to this. Since the 480i signalsreceived by the set are up-converted, IC511 will provide H sync at 31.5KHZ to pin 1. Capacitors C521 and C522will provide the necessary tuning for the oscillator to free run at the correct frequency. Pin 4 will receive the Hpulse for phase locking.

41


1

8

1

7

6

5 4

3

2

6

5

4

2

1 12

11

10

9

8

6

D BOARD

Q5020/EPIN OUT

1

4

1

4

1

4

FIGURE 10-2 - H OUT

DF VCC

D5015

C5045 R5062 R5055

CN5002

+135V

C5012

R5032

R5026 C5016

T5002HOT

+12VFROMIC5002 R5003

C5005

Q5008H DRIVE

N

C5010

R5011

Q5002

PCN5004

HDRIVE R5002

T5001HDT

R5031

C5019

PS5001

PS5002

D5007

D5003

D5009

R5046

R5049

Q5013H OUT

N

C5038

C5041R5074

C5039

D5013

R5007

C5091 C5032

C5092 C5052

R5008

C5088

L5007

C5051

R5030

C5043

C5042TO 5019/BH PULSESHAPER

CN4304

B-HDEF

RET

CN4107RETR-H

DEFREHG - HDEF

CN4206

10.2TVP14 7/11/02

-135V

Figure 10-2 illustrates the output section of the horizontal deflection stage. Since no flyback transformer isutilized, pulses will be generated by the collapse of the field in the horizontal deflection yokes and T5002. Thistransformer will provide a boosted voltage for the dynamic focus correction circuit via R5055 and D5015. It alsogenerates a positive and negative voltage source that will be applied to the red and blue CRTs. This will providethe necessary offset for centering since these tubes are not in the center of the optical path. Notice that thecollector of Q5013 does not have a B+ source. A negative 135V source is applied at the emitter and this voltagewill vary based on conduction of the pincushion output transistor, Q5020. Pincushion correction will be discussedlater.

Troubleshooting

The lack of a flyback transformer simplifies the troubleshooting of this circuit since it is usually the cause ofhorizontal output failures. The procedure to follow when replacing a shorted horizontal output transistor remainsthe same.

Occasionally, you will be fortunate to have the output transistor fail and nothing else is the cause. Usually,however, you end up losing the newly installed transistor if certain precautions are not followed. In the worstcase, this might cause the power supply switching transistors to fail. Always treat a shorted horizontal output asthough something else caused it to fail. The use of a variac and an oscilloscope will help insure this.

42


Once the new transistor has been installed, it is always a good idea to re-solder the connections on the horizontaldrive transformer. These transformers handle a lot of current to forward bias the B-E junction of the outputtransistor. As they get hot and run at high frequency, so it is common for solder connections to go bad. Solderthe connections well. You want the solder to flow up into the internal pin connections at the windings. Check thepincushion drive Q5020. It may also be shorted and may or may not have been the cause of the original failure.Either way, it will be the cause of losing the newly installed horizontal output if it is not checked. With that done,it is time to apply power.

Place your scope probe somewhere near the horizontal output transistor. Most scope probes are not able tohandle the direct spike level present here so this is a safe method. Just turn up the gain on the scope a little andyou will easily see the horizontal retrace pulse. Apply full AC power with the variac and watch for the horizontalpulses (assuming it appears) before the unit goes into protect. The H protect is muted for several seconds atturn and since the tubes are not lit yet, the pulse can be viewed briefly. Monitor the AC current level closely whiledoing this. Clean pulses should appear and be 11 to 13us wide. Any deviation from the normal pulse indicatesa tuning problem. Suspect T5002 or one of the deflection yokes. If the pulses are correct and excessive currentis being drawn (more than 2 amps), there is a problem in the driver circuit or the pincushion driver is in saturation.The horizontal output transistor will also get hot rather quickly.

One last situation that might occur is that the retrace pulse looks great but as you approach higher AC input, itbegins to jitter and dance on the scope screen. The current will also be higher than normal. Back off the ACpower quickly as this usually indicates excessive loading in the circuit.

NOTE: Many technicians prefer to “ring” suspected transformers. This is OK and is very good at detecting shortsin the windings. However, it is not 100% accurate. Problems in transformers sometimes appear under fullvoltage and current load, so the above procedure is very effective although it requires caution and close currentmonitoring.

Pincushion Circuit Troubleshooting

The pincushion correction circuit in this chassis is similar to those found in earlier model direct-view sets. Asseen in Figure 10-3, a DC coupled chain of transistors is utilized. What makes this type of circuit difficult totroubleshoot is the DC coupling. A failure of any transistor in the line can turn Q5020 completely off or cause itto go into saturation. It is simple in design but can be a headache to troubleshoot at times.

The vertical-rate parabolic correction signal from IC512 is amplified and inverted. It is then shaped and appliedto the pin driver. Notice that no horizontal gating pulses are used in this design. This is because the circuit is onlyvarying the amount of negative supply voltage to the horizontal output transistor to modulate the scan widthunlike the newer designs that modulate at the yoke return and/or the retrace damper diode.

Failures in this pincushion circuit usually involve the shorting of the pin driver, Q5020. Due to the DC coupling,one or more of the other transistors down the line may be damaged. On numerous occasions, the technician willreplace a shorted pin driver only to still have problems. There is an old audio amplifier troubleshooting methodthat works quite well for this situation.

Use your DVM and read across the B-E junctions of the transistors in the circuit. There are two things to look for:Zero volts or more than 0.6V. This will assist in locating any transistors that are biased on or have a shorted oropen B-E junction. Voltage readings across the E-C junction are also useful in locating open/off or shorted/saturated transistors. Since none of these devices run at saturation, so any voltage readings at 0V or supplylevel indicate a problem. The object is to find a transistor that is fully on or off to determine if that transistor isdefective or being switched on or off by the previous one.

43


4

Q5013/EH OUT

D BOARD

FIGURE 10-3 - PIN AMP

FROMIC512/11VDSPPIN E/W

CN5004

R5006

R5010

Q5003

+12V (D)

N

P

R5014 Q5011P

R5024 C5018

Q5007

R5015

R5025 C5022

R5036

R5037

R5044

C5044

R5052

R5053

P

Q5012

R5041

R5045

R5064

R5060

Q5017

PD5018

D5012*

R5056

C5031

C5030

Q5018

P

R5065

R5066

PQ5020

-135VFROM CN6002/3

*THIS DIODE IS REPLACEDBY A JUMPER IN MOSTSETS

10.3TVP14 5/28/02

Horizontal Deflection Loss

Because this chassis utilizes a separate high voltage circuit, the CRTs must be protected in the case horizontaldeflection is lost. If this situation occurs, the set will be shut down and the timer LED will blink in sequences ofsix. Referring to Figure 10-4, the horizontal retrace pulses are monitored by Q5019. After some clipping of thetop and bottom of the spike, it will be amplified by Q5014. As long as horizontal deflection is operating, Q5014will keep C5020 charged and Q5006 will be on. Loss of the H pulse will cause Q5006 to turn off, sending a highsignal to IC1009 to shut the set down.

Troubleshooting this circuit requires extreme care. Since the unit goes into immediate shutdown, there may beinstances where the protect circuit will need to be overridden in order to dynamically troubleshoot it. Alwaysdisconnect the C boards from the CRTs when working on this circuit!

Since the circuit has a mute transistor to delay it from activating at turn on (Q5009), the first step is to scopeQ5019-B for the momentary presence of horizontal pulses. This will verify if the horizontal deflection is workingor not and will assist in determining a legitimate sweep failure or a malfunctioning protect circuit.

44


D BOARD

8

9

C5020R5063

Q5019R5072

R5069R5068

NFROMC5041AC VOLTAGEDIVIDER INH OUT

R5027

N

-12VFROM IC6001

R5024

Q5016 R5048

R5061

Q5014

PR5039

R5042

C5026D5014

Q5015N

R5020

R5058

Q5009

P

D5008

R5033

C5020

H.P.

R5030

R5018

C5011

D5006

R5023

R5013D5002

R5004

CN506 HPROTECTTO IC1009/PIN 3A BOARD

C5002

NQ5006

H BLK(HP)TOA BOARDCN509

CN5004

FIGURE 10-4 - H PROTECT / HP10.4TVP14 7/17/02

Vertical Deflection

Figure 10-5 illustrates the vertical processing circuitry primarily created by VDSP IC512. Synchronization isachieved by VS entering pin 22. Notice the ½ H signal entering at pin 16. Since this unit generates internal,interlaced, horizontal scan, the vertical must be phase locked to start the odd and even scan in the properlocation. The parabolic pincushion correction waveform exits pin 11 and vertical drive is output at pin 1 as asawtooth.

Figure 10-6 shows the usual output design. An operational amplifier is used with negative feedback from thedeflection yoke return to maintain linear amplification of the drive signal. It is simple and works quite well. Yourarely see vertical linearity problems with this design. As with the pincushion circuit, the vertical circuit seems tocause problems for many technicians.

45


TODBOARDCN5004

COUNTDOWN

PROCESSOR(CDP)

DSP

VCO

IIC BUSDECODER

LPF

LDF

16

18

8

7

5

22

23

17

36

12

13

14

11

17

24

45

44

47 6

48 5

1

30

26

28

7

2

3

1

A BOARD

2

4

R713FROM1/2 HIC508/5 R709

C675

R757

R756

C678

R700FROMVSIC516/3BUFFER

C635

VBLKFROM CN509/6V OUT IC

#R645

# NOT MOUNTED

R623

VTM

VC1

OPO

OP1

PHA

H IN

IC512VDSP

CXD2018A ADR

SAW

XSOP

SOP

C651

AFCDAC

DAC

DAC

PAR

SCL

SDA

FROM IC1008MAIN CPU

R779

IC514

C644

R692 R534

C630

C657

C660

C667

V DRIVE

TO IC507/2H JUNGLE

PIN (E-W) CN509

VBLK/VP

FIGURE 10-5 - VDSP10.5TVP14 5/28/02

D BOARD

5

3

4

1

2

6

7

6 3

5

4

7

1

3

R5028+15V

CN5002

L5003

C5024

CN5009

DEF5V

C5033 C5035

C5029

D5017RD24ESB1

R5075

R5073

R5043

C5049

R5047

C5028R5038

R5021

L5004

CN5004

V DRIVEFROM IC512/11

-15VCN5002 R5029

C5025 D5016RD24ESB1

TO CIRCUITNOT USED

D5011

C5037 C5034

D5010

R5040

C5023

IC5004V OUTSTV9379

C5089

C5036

R5059

C5040

R5035

R5034

Q5005

R5016

P[

Q5010

R5020

R5017

N

D5004

C5013

C5090

R5076

L5009C5048

C5047

R5077

R5067 R5071

FROM+12V

R5012

D5001 CN5009

R5155

V PROT.TO IC1009OSD CPU

VDEF

ZB

ZG

ZRVRET

CN5008

FIGURE 10-6 - V OUT 10.6TVP14 5/29/02

46


Vertical Deflection Troubleshooting

No Vertical Deflection: The first instinct of the technician is to go after the vertical output IC1501 and understandablyso. It is a drive component with heavy current usage and heat dissipation, and it is usually the cause of thefailure. It is amazing how many techs change this IC first without doing a few checks. What should you do nowthat the new IC has not cured the problem?

The first check that you should perform (and this applies to all Sony televisions of the last seven years) is tocheck the voltage level of the clock and data lines on the I2C bus. They are conveniently labeled SCLK andSDAT. The DC voltage should not be lower than 4.6 volts. If either of these lines is loaded down, the verticaloscillator will not start. This is the number one cause of multiple component replacement for a simple verticalproblem. You should always check the clock and data level whenever you have a strange problem, particularlyif it appears that you more than one problem. Although most television chassis’ will not produce vertical deflection,some will generate other symptoms. As an example: The AA-2W used in Sony’s KV32/36XBR200 sets providesa magenta raster with no video and insufficient vertical height. Assuming the bus is okay, move onto the nextscenario:

Check for V drive at IC5004/pin 1. Since this unit shuts down during a vertical failure, you will have to override byshorting Q5005 E-C. Unplug all three CRT sockets when doing this. It is obvious why this unit shuts downduring a vertical failure. If the sawtooth signal is getting to IC5004, the problem is in the output stage. If not,work your way back to IC512 and its associated circuits. Assuming the +15V and –15V supply rails are present,you are only left with a bad driver IC, open yoke or open connection to the yoke. The V protect circuit could alsobe engaging due to a failure there. If the sawtooth signal is not present, work your way back to IC512 and itsassociated circuits.

Repeat Vertical Output IC Failure: If IC1509 fails immediately upon replacement or soon thereafter; it is usuallythe fault of C5037. This is the boost capacitor. It charges to almost 30VDC during the lower half of the verticalsweep to provide additional voltage to allow the beam to retrace to the top rapidly. When this filter dries out oropens, the output IC will attempt to accomplish the retrace but the negative feedback line will resist the suddenvoltage kickback from the yoke and the –15V drive will cause the IC to draw excessive current. In smallertelevisions, a boost capacitor failure causes slight loss of vertical at the top with some fold-over.

Insufficient Vertical Height: Either the vertical output IC is being told what height to display or it has a problem andis unable to comply. Due to the nature of the operational amp within IC1509, it is rare for it to be the cause.Operational amps have massive amounts of gain, which is why they need negative feedback to keep them undercontrol. Gain problems are most likely to be caused by improper supply voltage (very rare) or problems in thefeedback line. This is why you should always scope the feedback line when height or linearity problems arise. Inthis chassis, the best point is the top end of the ground return resistors (R5067 or R5071). What should normallybe here is approximately 1VPP of vertical rate sawtooth. If there is a problem here, you will observe one of twothings: A significantly larger sawtooth level, or, horizontal frequency contamination in the sawtooth. A largesawtooth indicates one or more of the ground return resistors or the thermal compensator TH1501 has opened.The negative feedback of the op amp will respond by reducing gain. If there is a large amount of horizontalcomponent in the feedback, the amp will also reduce gain since the average DC level will be higher at thisfrequency. The vertical deflection yoke windings are right next to the horizontal windings so it is very easy toinduce this into the vertical return and low-pass filtering is needed. Suspect an open C5028 at this point.

Should the feedback line check OK, you now have a possible input problem. IC 512 can cause this and it isdifficult to verify without replacing it. Before changing IC512, try one more thing: Replace the EEPROM, IC1007on the A board. It has caused this symptom. It is less expensive and only has eight legs.

47

11. RA-4/4A High Voltage Circuit Troubleshooting

Chapter 11 - RA-4/4A High Voltage Circuit Troubleshooting

HVREG

BLOCK

12

D BOARD

TO HV REGPWM

BLOCK

5

6

7

4

3

2

1

FIGURE 11-1 - HV DRIVE

+135V

R8002

D8002

D8001

R8024

R8123

C8010 N

Q8001

R8001

FROM HVSTOP 1&2Q8019/CQ8021/C

HDRIVE

+12V

N

Q8005

R8010

R8011 R8015

CN8003JUMPER PLUG

R80041k

R800522k

R800722k

P

Q8002

R8008

C8007

C8006

R8003

Q8003

N

R8009

C8008

T8001HDT

C8004

11.1TVP14 5/29/02

TOHVOUT

Overview

The RA-4 chassis reintroduced the separate high voltage circuit that had been eliminated in the RA-2 and RA-3chassis. This design offers better control of the high voltage level, resulting in more stable brightness and picturesize fluctuations. It is also a complicated circuit with regulation control and redundant protection circuits for over-voltage and current problems. The circuit functions the same as a conventional horizontal/HV stage in mosttelevisions and troubleshooting is relatively the same. When regulation or shutdown problems occur, diagnosisbecomes more difficult because the circuit is critical for X-radiation control and to protect the small CRTs. Theanode cap is very close to the grounded mounting brackets and the deflection yoke. It can easily damage theCRT if it leaks out of the anode cap.

Regulation is performed at the driver and output stages. Figure 11-1 illustrates the drive circuitry. The B+supplying T8001 and Q8003 is varied by a PWM controlled regulation stage that controls Q8001 and Q8002,which functions as a variable resistor across R8005 and R8007.

Figure 11-2 shows how the circuit is similar to flyback circuits found in other units and shows the regulation of theoutput stage. The same PWM circuit that controlled the regulation in the drive section will control Q8008. ThisFET will vary the ground return for Q8007 emitter. The circuit drives the flyback transformer, T8003 and T8002that will generate the heater and 200V bias voltage for the CRT cathodes. The regulation and protect circuits willbe reviewed later in the troubleshooting of shutdown.

48


D BOARD

+135V

6

7

4

3

2

1

1

2

3

4

6

7

8

9

18

17

16

15

13

12

11

10

1

HV

2

3

4

5

6

7

8

9

10

12

11

HV

T8001HDT

FROMHVDRIVE

Q8007 D8011

D8007R8019

C8018

D8010C8014

C8021

C8012 C8009

FB8001Q8008

L8003D8009D8008

R8023

T8002LOT

PS8001

R8199

L8004

D8003

FB8002R8012

HEATERS

D8013

C8020

C8023

R8039

R8038

D8014

R8016

C8025R8200

R8020

R8183

H+H-210VTOHVBLOCK

T8003FBT

TOFOCUSBLOCK

ABL(HVSTOP1)

NL8001

C8032 TO HVSTOP2

PWMFROMHV REG

FIGURE 11-2 - HV OUT 11.2TVP14 5/30/02

Troubleshooting

Shorted HV Output Transistor: As with all horizontal output transistors, care must be taken to avoid failure of thereplacement part. Always check Q8008 since it can be easily damaged by the large current surge if Q8007shorts. There is even the possibility that Q8008 was the cause of the failure. Disconnect or short the B-Ejunction of Q8002. This will run the driver stage at low level. The output regulator will now try to compensate soit must also be disabled. This can be done by unsoldering the gate of Q8008. The main relay can now bejumped and power can be applied with the variac while monitoring the pulse at Q8007 collector. This is a littleextra work but it is better than losing the replacement part(s) and it is part of a critical safety circuit.

Place your scope probe somewhere near the HV output transistor or flyback. Most scope probes are not able tohandle the direct spike level from the flyback so this is a safe method. Just turn up the gain a little on the scopeand you will easily see the retrace pulse. Apply full AC power with the variac and watch for the pulse (assumingit appears) before the circuit shuts down. If the flyback is defective, one of two waveforms is likely to appear.The first may look like a sinusoidal waveform with a distinct ringing appearance. This definitely indicates flybackproblems. The second phenomenon will be a retrace pulse with a second, lower level, “phantom” pulse. It issometimes normal for this “phantom” pulse to appear at low B+ input levels but it should disappear quickly as youincrease AC voltage. Monitor the AC current level closely while doing this. If the phantom pulse remains andcurrent starts to rise, it is time to replace the flyback. One last situation that might occur is that the retrace pulselooks great but as you approach higher AC input, it begins to jitter and dance on the scope screen. The currentwill also be higher than normal. Back off the AC power quickly as this usually indicates excessive loading ofsecondary lines. In this unit, it can be loads on T8002. Measure for shorts on the filament and 200V line. Theflyback T8003 only has two load circuits and they are the HV and focus blocks

49


If a clean pulse appears with AC current staying well below 1.5 amps, re-connect Q8008 and Q8002 (or the shortif you disabled it this way). Apply power once again and continue monitoring the flyback pulse. Do not worryabout excessive high voltage problems. The main relay is not part of the protection circuit for high voltage. If thehigh voltage rises too high or flyback current is excessive, the horizontal drive pulse will be cut off and the circuitwill stop functioning. If it goes into HV protect, proceed to the next section.

High Voltage Shutdown: This will cause seven blinks of the timer LED. The unit will not go into full shutdown.Only the HV section will cease to operate so there will be a condition of no video with audio present (assuming asource is being input). The variac will be a valuable tool in this case. Apply full AC and watch the current as theunit goes into protect. A high spike of 2 amps or more is a clear indicator that an over-current condition exists. Ifthe circuit is engaging because of excessive HV, readings of less than 1 amp will show. If the cause is over-current, care must be taken to avoid causing the HV output transistor to fail. If the current reading is low, theregulation or output tuning circuits are suspect. Another possibility is the protect circuit is engaging because ithas developed a problem.

Excessive Current Draw: In most cases, the flyback transformer is the least likely suspect. Shorted windings willaffect the delicate tuning so drastically that the HV output transistor will fail. The more common causes areexcessive current demands on the secondary windings of T8002 and T8003. A quick check for shorted componentsor shorts to ground on the secondary of T8002 will quickly locate the cause or eliminate this section. Highvoltage blocks are more common as is a shorted CRT. Removal of these devices from the circuit is the bestprocedure. All of the above items will cause rapid shutdown of the circuit. If the protect circuit does not engagefor several seconds, a CRT of loss of 200V cathode bias is likely and should expose itself with one or all of thetubes displaying a bright raster before the shutdown.

Normal Current Draw: This could be a true high voltage problem or a malfunctioning protect component. It is notrecommended to insert a HV probe into the anode cap of a CRT to check the HV level. If the unit has excessivehigh voltage, it can easily arc from the anode cap since you have lifted it. A safer way is to disconnect one of theCRT anode lines from the HV block and try to get a reading there. Even this method is not the best. If the highvoltage is rapidly rising to extreme levels, the protect circuit may shut it down before the probe can achieve anaccurate peak reading. One method is to disable the regulation circuits as mentioned previously. If the highvoltage stays on and the probe shows lower than normal high voltage, the regulation stages will need to bechecked. If it still goes into protect, a “misfiring” component is now the part to look for. Block diagrams for bothregulators and the protect circuit will now follow with a brief description of each to assist in locating the failedcomponent.

Regulation

A PWM circuit is used to control high voltage at the driver and the output stage. It consists of two stages: One tosample the high voltage from the HV distribution block and the other to monitor this voltage and generate theappropriate PWM control.

High Voltage Monitor Stage: In Figure 11-3, this diagram illustrates how a sample of the HV level is taken fromthe HV distribution block and applied to pin 5 of IC8007, a buffer, and output to pin 9 where the voltage iscompared to a 7VDC source divided down from the 135V B+. It is once again buffered and sent out by pin 1 tothe PWM comparator. The nominal voltage at this point is 1.5VDC. This is a good monitoring point for highvoltage troubleshooting. The voltage will react inversely to the actual high voltage in the HV block. By monitoringIC8007/pin14, the HV sample feedback will indicate if the excessive high voltage is originating at this point. If thevoltage reads lower than 1.5VDC during a HV protect, the HV block and the paths routing through IC8007 are OKsince they are sending correct feedback. The regulator output stage shown in Figure 11-4 may be at fault.Shorted or open filters may be present at HV output Q80087. If the voltage is higher than 1.5VDC, the HV blockor IC8007 is at fault.

50


HVBLOCK 3

D BOARD

6

57 9

108

2

31

2

1

FIGURE 11-3 - HV REGULATION CONTROL

R8119TO HVPROTECT 2IC8008/3

7.2V

R8174

IC8007 1/4

CN8006D8041

RD13MC8068

+12VQ8025 P

R8166 D8039RD10ES

R8177

R8178+135V

D8042HZT33

+12VR8167

C8090 R8172

R8128

C8076

R8126

6.9V

Q8024

N R8127

R8173 R8195

C8094

Q8026P

R8139

R8136 C8082

C8070

IC8007 1/4

C8052

R8138

1.5V

14.2V

R8196

R8168

C8074

TO IC8002/5HV REGULATIONPWM

R8093

IC8007 1/4

R8201

R8119

11.3TVP14 7/11/02

PWM Stage: Figure 11-4 illustrates the second half of the HV regulator. There are two must-haves for a PWMcircuit to function: The first is a sample of the voltage to be regulated, and a sawtooth or triangular shapedwaveform. The horizontal pulse is utilized to provide the stable timing of the sawtooth signal applied at pin 6 ofIC8002. The pulse will be amplified and shaped by peaking and integrators located in the upper half of thediagram. Pin 5 of IC8002 will receive a sample representing high voltage level from the circuit previously describedin Figure 11-3. Since the sawtooth signal is applied to the inverting input of IC8002/pin6, any rise of the DCvoltage at the non-inverting input at pin 5 will cause the comparator to output a high only when the level of thesawtooth is greater than the DC voltage input. Since the sawtooth enters the inverting input, the positive durationof the pulse is increased and the HV regulator driver, Q8008, will be turned on for a longer period.

This pulse can be used to control the on time of an amplifier (such as in this case), or filtered to provide a DCcorrection voltage. This is the essence of how all PWM regulators function. An incorrect DC monitor voltage orincorrect level, shape and frequency of the sawtooth reference will generate erroneous PWM timing pulses.Since the reference signal is generated from the H pulse, frequency deviations are unlikely in this circuit.

The PWM will be output to Q8016 and provide control of the conduction of Q8008 at the emitter of HV outputQ8007 (Figure 11-2). Since Q8008 is a FET, its gate has high impedance at its input. Q8015 will assist in pullingthe signal down to maintain a uniform pulse shape. The signal will also be sent to HV drive stage to control thevoltage at Q8003 (Figure 9-1).

51


D BOARD

3

21

76

5

6

57

R8027

+12V

P

HDRIVE R8021

R8010

R8031

C8019

R8028Q8009

D8015C8029

R8027

Q8010

R8044

R8059

TOQ8008

FROMQ8024/CAND IC8007/1HV REGULATIONCONTROL

R8060

R8067

R8071

C8033

C8045IC8002

R8082

+12V

R8070

Q8016N

R8075 Q8015

P

R8084

R8083

Q8018N

R8074

IC8002

R8077

D8017

R8015

+12V

Q8022R8085

NR8095

R8113

R8108

D8023

R8096

R8114

C8066

IC8008

-12VC8064

11.4TVP14 5/31/02FIGURE 11-4 - HV REGULATION PWM

High Voltage Protection

The HV monitoring section utilizes two separate circuits to provide redundant protection.

HV Stop 1: Figure 11-5 contains the paths for the first set of protection components. HV level is monitored fromthe HV block by pin 3 of IC8008. This is compared to a reference of 9.3VDC at pin 2. If the high voltage risesabove acceptable levels (34KV), pin 3 will exceed the reference. Pin 1 will go high. The H pulse driving the HVcircuit will be grounded by Q8019 and the high signal will sent to OSD CPU IC1009 to flash the timer LED insequences of seven.

Flyback transformer current is monitored by applying the ABL voltage to Q8027. Under normal conditions, ABLis a positive voltage between 2VDC and 6VDC. If the current rises to an unacceptable level, the ABL voltage willgo lower. Once it drops below .6V, Q8027 will turn off, sending a high to pin 3 of IC8010. The H pulse will be cutoff and IC1009 will respond the same way as the over-voltage condition described above.

52


3

21

2

31

2

31

FIGURE 11-5 - HV STOP 1

R8176

+12V

Q8027FROMHV STOP 2ABL

R8170

C8092

D8036

R8116 C8071

C8062

R8106R8115

+12VQ8023

P

D8024

FROMIC8007/7REGULATIONCONTROL

C8059

5.9VIC8010

R8111

9.3V

D8025

+12V

C8065D8030

IC8008

7.4V

+12V

R8107

5.1V

+135VR8134

R8133

R8182

C8072

D8031

4.6V

D8027

R8091

R8087

+12V

R8102

C8060

IC8006

R8120

C8078 R8137

Q8019

TOD8021ORHV STOP 2

C8053

N

TO HDBUFFERQ8005/B

11.5TVP14 6/3/02

HV Stop 2: Referring to Figure 11-6, the second HV protect circuit is shown. It functions in a similar manner asHV stop 1 with a few differences. Q8031 monitors voltage from the flyback transformer rather than the HV blockassembly. Pin 5 of IC8010 will receive this signal and, instead of comparing it to a fixed reference, the ABLvoltage is used. The reason behind this design is to shut down the high voltage quickly if it is rising and flybackcurrent is simultaneously increasing. This severe condition can damage multiple components. The ABL voltageat pin 6 will drop, while the HV sample at pin 5 increases. Q8028 will monitor flyback current in the same manneras HV stop 1.

53


6

54

3

6

1

3

21

5

67

6

57

9 9

A BOARD

D BOARD

R8165

+135V

R8164

R8163

R8161 R8162

FROMABLT8003/11

CN8003JUMPERPLUG C8086 R8160

R8156

R8129IC8009

R8123+12V

R8118D8035RD5 - 1M D8048

R8135R8121

D8032FROMT8003/6 C8077

R8140 C8084

R8202 R8194

CN8007 R8193

+12V

Q8028

NR8171

C8093

R8125

C8073

R8117

+12V C8083

Q8031N R8091

C8104R8191

R8192

D8050

R8175

C8096 D8040

C8075C8075

R8122

R8110

R8609IC8006

D8045MA3041

D8038RD13M

IC8010

D8026+12V

R8103

R8094Q8021

R8092 C8054N

CN8009

R8058C5095

CN506

C8111D8021

+12VR8097

TOQ8027/BHV STOP 1

TO HDBUFFERQ8005/B

TOIC1009OSD CPU

FROM HVSTOP 1IC8010/1& IC8008/1

FIGURE 11-6 - HV STOP 2 11.6TVP14 7/11/02

+12V

Troubleshooting Tips: Since there are two sets of protect circuits, isolating which one is activating is the first step.This is easily accomplished by monitoring either anode of D8021 in Figure 11-6 to determine which circuit issending the high signal. This may only be useful if a problem exists within one of the devices in either protectcircuit. A legitimate high voltage problem may trigger both protect circuits. If high voltage and current levels havebeen absolutely verified to be within specifications, this is the only time when it is safe to defeat these circuits fortroubleshooting purposes in order to locate the component causing the false shutdown.

54

12. RA-4 Video Circuit Troubleshooting

Chapter 12 - RA-4 Video Circuit Troubleshooting

Overview

As mentioned earlier in this manual, the RA-4 chassis introduced Sony’s first rear projection television with linedoubling capability. New circuitry was designed to perform this task. The DRCTM, or digital reality creator, wasadded to assist in doubling the horizontal scan lines by interpolating the video information for each of the 480interlaced lines of the incoming NTSC signal. This would minimize the jagged edges that occur by simplydoubling the lines. A more robust picture and picture circuit known as MIDTM, or multi-image driver, was alsoadded to further enhance twin picture viewing and channel scanning. All of these new features required digitizingof the video signal and that meant more components and a more complicated set of paths for the video to follow.The upside of these add-on features is that they can be used to assist the technician in isolating the source of avideo failure.

Figure 12-1 will be the main diagram to be used for isolating video problems. It provides a great overall view ofthe key video processing circuits and the different paths the various inputs and features will follow. The ability ofthis chassis to accept component video allows the customer to take advantage of the higher chrominance resolutioncapabilities of this format. It also provides a great troubleshooting path for bypassing most of the video circuitry.

Referring to Figure 12-1, it can be seen that A/V switch, IC515, controls all of the video selection except forcomponent sources that can be connected to the video 5 input. Any signal that is not a component format willhave the possibility of traveling either one of two paths: The main or the sub. All non-component video for mainviewing will route through the A/D converter, IC1309 (not shown on this diagram) and into the 3D comb filter,IC1306. Even S video sources will be routed here. The 3D comb filter contains noise reduction circuitry for theluminance signal and this will be done for S video sources. Composite signals will have chrominance separatedfrom the luminance. This is all performed in a digital format and then D/A converted within IC1306 to outputseparated luminance and chrominance.

The Y/C signal now enters a decoder circuit. The 3.58MHZ carrier and sync will be removed so that only the R-Y and B-Y chrominance levels are left. IC1307 is a switch that allows closed caption information to be insertedand provides a direct path for a component video source directly to the DRC. The path will split at this point. Onewill go to the BM board that contains the MIDTM to provide main video for the picture and picture feature. Theother path will take the component signal to the BR board where the DRCTM will perform the line doubling. Thevideo information, now synchronized at 31.5KHZ, will enter the video processor IC511 where OSD can be insertedand exit to the CRTs as RGB video.

The sub video path will be processed along a different path. A conventional comb filter is used and chrominancewill be decoded by IC1301. The sub component signal now enters a YUV switch, IC1302. This IC performsseveral functions. It allows the insertion of closed caption information, main CPU OSD, and provides a point toroute a component video source to the MIDTM processor.

IC1004 supplies on screen graphics such as user menu and input/channel information. The BD board (autoregistration) supplies RGB information since it generates its own menu during convergence alignment along withdot and crosshatch patterns.

55


TU501MAIN

TUNER

TU501SUB

TUNER

COMPOSITE+S VIDEO

1-5

VIDEO 5COMPONENT

VIDEO

SELECTOUT

IC3063D

COMBFILTER

CM501GLASSCOMB

IC515A/V SWITCH

IC1305MAIN

CHROMADECODER

IC1307YUV SW.CCD MIX

IC1008MAINCPU

IC1301SUB

CHROMADECODER

BRBOARD

DRC

BMBOARD

MID

IC511VIDEO

PROCESSOR

IC1302YUV SW.PIP OSD

MIX

RGBBUFF.

IC1004OSD

PROCESSOR

BD BOARDPJE OSD

CCDMAIN Y/COMP.

MAIN

C

MAIN YORCOMPOSITE

SUB

Y

C

SUB C

SUB Y

CYUV

CCD

YUV

SUB Y

YUV

YUV

YUV

RGB

PIP

CV

RGB

RGB

RGB

YUV

RGB

FIGURE 12-1 - VIDEO PATH BLOCK 12.1TVP14 6/4/02

Troubleshooting a “No Video” Condition

Many situations can cause this condition. The presence of audio is usually a good diagnostic tool, but the setmay be in one of the external input modes so it might not be there for you to hear. What you should do is look forthe initial “must haves” and follow that order to isolate the cause.

The first check is for the presence of high voltage. You should be able to hear it come up in most cases. If itdoes, the next concern is that it is staying on. You may be dealing with a HV shutdown. Fortunately, this chassiswill indicate the shutdown by blinking the timer LED in sets of seven. In that case, refer to the earlier chapterdealing with high voltage shutdown.

The next step is to wait at least 15 seconds and observe if the timer LED begins to blink in sequences of five. Younow know that you are dealing with an AKB error. Go to Chapter 27, which specifically deals with AKB problemsand troubleshoot accordingly.

Your next ally is the OSD feature. Try pressing the channel up or down, the video input select or the menu buttonon the remote. If no OSD appears, the video process IC is suspect since OSD has its own path directly into it andit is highly unlikely that both the OSD and video path have simultaneously failed. Anything is possible so performseveral more checks before you change IC511. If OSD is present, the next test will be even more important.

Using the twin picture mode is an excellent procedure for isolating video problems. When in this mode, the mainand sub video paths are mixed and placed side-by-side. It is the only time the main video source will bypass theDRCTM circuits. What is seen in this mode will provide crucial information. In a set that is operating normally, themain video source will appear in the right box and the sub video in the left.

56


N

N

3

5

6

1

2

4

63

62

64

60

59

61

32

31

56

58

52

54

53

49

42

40

38

45

47

343536

25

29

7

12

13

18

19

24

A BOARD

4

1

C697

C698D524

D525R876

R875J5053 4

V

D550

R862

C706

R891

LR892

RR870

DETOUT 2

Q506

L OUT C685

R OUT C690

TU501MAIN

TUNERBTF - WA

411

DETOUT 2

+9V

Q526TU501SUB

TUNERBTF - WA

411L OUT

R OUT

C688

C687

R907

D532

C707C708

D543

+9V

R510 C689

R554

R560

PQ517

R804

R814

R607 C686 R794

R664

R682

PQ518

R790

R799FROMIC1008

MAIN CPU

R821Y1

R823C1

+9VR843

SSW1R824

V1R819

R820L1

D537

R822R1

R808TV VMAIN

TVL MAIN

TV R MAIN

TV V SUB

TV L SUB

TV R SUB

SDASCL

MAINYC

L

R

V OUT

Y IN

SUB V OUT

SUB C IN

IC515AVU SWITCH

CXA1845Q

SUB Y IN

SUB Y OUT

SUB C OUT

Q533

R759N

C673R755

R736

+9VN

C643L523

C639R745

TO IC1302/28

VIDEO 3 J506

VIDEO 4 J507

VIDEO 5 J508

TO BUFFER Q532

TO BUFFER Q536

TO CN512/1TO CN512/3

TO KBOARD

+9VR720

R816

CM501

VIDEOIN

C664

Q548 Y OUT

R727

C656

R717

TO IC1301/32

SELECT OUTJ502

FRONT VIDEO 2 J3201

ALL ZENERS ARE UDZ - 10B

12.2TVP14 6/5/02FIGURE 12-2 - INPUT SWITCHING

Video Appears In Both Boxes: The main and sub video process paths are working correctly. The MID is sendingthe video directly into IC511. The problem is likely located on the BR board. The DRCTM circuit on this board isconstantly running and not controlled by the I²C bus. IC511 controls the selection of the video source. If videosignals are present at pins 67, 69 and 69 of IC511, replace IC511. No signals at these pins indicate the BR boardis not sending up-converted video. Check to see if video is entering the BR board and the 3.3V and 5V lines areOK. If they are present, replace the BR board. It is not serviceable.

Video Appears In Left Box Only: The sub video path is OK. Once again, the DRCTM is bypassed. This leaves asmall number of components to check. Begin working your way back from the YUV switch, IC1307. Scope thevideo signal path back through the main decoder, 3D comb filter, A/D converter and A/V switch IC until you finda signal and troubleshoot the isolated component.

Screen Is Still Blank: Assuming high voltage is present and the set in not in AKB blanking, this leaves IC511 asthe cause. It is not able to process video from either of the inputs from the MIDTM or DRCTM circuits. There is noneed to check the RGB output path to the CRT boards. Since the unit is not showing AKB problems, the IKpulses are getting to the CRTs via this path.

Gray Background Appears With Two Black Boxes: IC511 is OK. This signal is generated by the MID. The mainand sub video paths are not working. Since a failure in both paths at the same time is unlikely, suspect A/Vswitch, IC515.

As you can see, the MIDTM circuit provides an excellent troubleshooting tool for video problems. All of the abovetechniques were accomplished by using the very basic video block diagram in Figure 12-1. Block diagramsproviding more detail will be provided in the pages that follow to assist in troubleshooting the isolated section.

57


A BOARD

4

1

7

10

22|

20|

17|

13

24

6

76

96

57

59

60

75

61

74|

67

66

6584

83

50

9|2|

99

28|

13

11

10

12

30

98

16|

19|

26|

22

2|57

1039363431

13

29

28

27

14

C1493

LUMINANCE/COMPOSITEFROM YBUFFERQ1448

VIN

R1544C1490

VRT

VCLC1493

C1494R1495

VRB

C1495

COMPOSITE SYNCFROM Q1341/CS BUFFER

FROM Q1345/ECHROMA C BUFFER

FROMRESETQ1015/C

R1509

FROM IC1008MAIN CPU

SCL

SDA

Q1359

N

DB1|

DB8

CLK

IC13098 BIT ADC

uPC659AGS

PCL

C1409

DYC00

DYCO1

AYO

ACD

IC13063D COMB FILTER

uPD64081BGF-3BA

FSCI

DYC09

DYC02

MAO

MABALTF

STO MIOO

MIO15

CSI

ACI

RSTB

MWE

MCAS

MOE

SCL

SCA

X1

MRAS

LUMINANCE

CHROMA

P

Q1349

C1496 R1434

N

A0

A8

IO1

IO16

R1391

C1370

R1437

WELCAS

UCAS

OE

RAS

IC1304FRAME

MEMORYuPD424210L0

TO Q1354/BBUFFER

TO Q1358/BBUFFER

+9VR1414

FROMIC1305/30FSC

Q1348

12.3TVP14 6/24/02FIGURE 12-3 - 3D COMB FILTER

58


FIGURE 12-4 - MAIN CHROMA DECODER

1

2

37

36

35

26

A BOARD

32 34 38 39

14

15

16

10

18

19

20

30

22 8

28R1543

FROM COMBFILTER AYOIC1306/84

FROM COMBFILTER ACOIC1306/83

C1332

R1446

X1303500kHz

R1449C1413

FROMMAIN CPUIC1008MSDA

MSCL

R1425

R1426

+5V

R1452X13053.58MHz

C1422

C1385

CERA

AFC

YIN

VSYNC

CIN

HSYNC

SDA

SCL

ADR

R1546

PQ1367

Q1366N

9V

9V

R1393

R1400Q1331

R1405

Q1332

C1381

P

C1376

C1389

R1463VTIM

HTIM

SCP

CPINQ1321

PY OUT

U OUTQ1322

P

R1375

9V

Q1323

Q1338

P

C1483

Q1328 N

R1401

R1402N

R1408

R1464

CV-Y

SELY CLPP

Q1330

R1374

9V

C1457

C1456

C1435

R1383

P

Q1343R1445

IC1008/8 VPCN516//4 BRBOARD, CN518/7BM BOARDIC1008/7 HPCN516/2 BRBOARD, CN518/8BM BOARD

TO IC1307/1YI IN

TO IC1307/2CBI INTO IC1307/3CRI IN

9V

TO MAIN YUV SW.IC1307/4 & 27YUV SEL1/SEL2

TO IC1306/503D COMB

IC1305MAIN CHROMA

CXA2109AQFSCM

IC1307MAIN YUV SW.

CCD MIXCXA2119M

12.4TVP14 7/11/02

59


A BOARD

24 28 4 27

1

2

3

5

6

7

9

10

11

20

12 13 14 8

22

16

17

18

C1482

FROM Q1343FSC DETECT.

FROM Q1366/ECOMPOSITEVIDEO Y

FROM IC1305/18C1457

FROM IC1305/19C1456

FROM IC1305/20C1455

IC1305 ISMAIN CHROMADECODERFROM VIDEO 5COMPONENTINPUT

C1467

C1466

C1465

C1472

C1471

C1470

FROM IC1008/32

FROM IC1008/33

FROM IC1008/34

FROM IC1008/36

IC1008 IS MAIN CPU

R1530

C1464C1463

R1503

FROM IC1305/16SCP

C1462

DVD Y CV Y SEL Y

Y1 IN

CB1 IN

CR1 IN

Y2 IN

CB2 IN

CR2 IN

Y OUT

CB OUT

R IN

G IN

B IN

YS

YC1 P CBCLP CRCLPCLPP

CR OUT

Q1328

+9V

N

R1538

TO Q1324CCD BUFFER

TO IC1305/34MAIN CHROMA

+9V

Q1325 R1320

NR1527

TO CN516/10 BR& CN518/1 BM

R1309

+9VR1537

Q1326

R1528

R1536

R1536

N TO CN516/8 BR& CN518/3 BM

R1529

+9V

Q1327N

R1308

TO CN516/6 BR& CN518/5 BM

R1521

12.5TVP14 6/7/02FIGURE 12-5 - MAIN YUV SWITCH AND CCD MIX

IC1307MAIN YUV SWITCH

CXA2119M

60


BR BOARD

10

8

6

2

4

IC3063 CH8 BITADC

IC30313.5MHz

PLL

IC466SYNCSHIFT

IC30154M

CLOCK

IC305TBC

IC6441 MB

MEMORY

IC6451 MB

MEMORY

IC562uP

CONV.CDX2070Q

IC460CLOCKDRIVER

IC463uP CONVERTER

CXD2062QIC641

CLOCKDRIVER

IC304uP

CONV.CXD2071R

2

4

6

8

10

13

14

FROMCN516A BOARD

CN302

M-YM-B-YM-R-Y

8 BITY

8 BITC

M-VD M-HD

8 BIT Y

8 BIT C

CN301RC-Y

RC-B-Y

RC-HD

RC-VDTOA BD.CN511

NOM Y

BRMI

CN302

13M

27M

12.6TVP14 6/11/02FIGURE 12-6 - DRC (DIGITAL REALTY CREATION)

61


BM BOARD

IC003MAIN ADC

IC002ACHPLL

IC008C CHPLL

IC001MEMORY

IC009MIDCPU

IC005NVM

IC014SBADC

B CHPLL

IC013MEMORY

IC010MID

CONTROLLER

1

3

5

7

8

12

19

20

1

3

5

7

8

10

11

12

13

14

16

18

20

CN001M-Y

M-R-Y

M-B-Y

M VD

M HD

VP

MSCL

MSDA

MID 12C

CN002S-Y

S-B-Y

S-R-Y

S-HD

S-VD

MID-V

MID-H

MID Y-SMID R-Y

MID B-Y

MID Y

12.7TVP14 6/10/02FIGURE 12-7 - MID BLOCK

62


BM BOARD

BR BOARD

BD BOARD

A BOARD

20

18

16

14 OR

13

9

12

10

8

6

4

2

6

7

8

9

15

2

1

12

3

13

64

63

62

61

35

37

39

41

59

65

6636

38

40

67

68

6933

3145

46

47

48 32

2949

50

51

5228

Q524, Q540BUFFER

Q516, Q539BUFFER

Q510, Q538BUFFER

Q501BUFFER

Q503 - Q505AMP, BUFF.

1

2

6

5

1

3

5

8

7 6

7

3

CN002 CN513

YS

CN301 CN511

CN1702 RE-YS

RE-R

RE-G

RE-B

CN522

FROM Q1012/E

FROM Q1002/E

FROM Q1001/E

FROM Q1003/E

FROM IC1008/610 SYNC SEL

Q546Q530

MID XRC

VD

HDMID HD

MID VD

RC HDRC VD

IC509SYNC SW

EY IN

ECB IN

ECR IN

TCACR SW

R OUT

G OUT

B OUT

IK IN

VM OUT

VI IN

HI INR S/H

G S/H

B S/H

CRI IN

CBI INHP IN

YI IN

SCPSY/SM IN

LR1 IN

LG1 IN

LB1 IN VBIK

HS OUTYS/YM2

LR2 IN

LG2 IN

LB2 INVS OUT

IC511VIDEO PROCESSOR

CXA2101AQ

C622

C617

C611 R6350 OHMS

ORQ620,Q525,

Q560

+5V

CN503

TO CN701CR BOARD

TO CN4102/2CB BOARD

FROM CN509/9HBLK (HP)

IC510

FROM IC512/36VTM

TO I507/1H JUNGLE

TO IC512/22VDSPIC516

BUFFERTC7W08

12.8TVP14 6/10/02FIGURE 12-8 - VIDEO PROCESSOR

63

1. Features

Chapter 13 - Troubleshooting the RA-4A Chassis

OverviewThe RA-4A chassis shares many of the circuit designs with its predecessor, the RA-4. It is still reserved for usein the high-end XBR series, which includes the KP53XBR300 and the KP61XBR300. Its greatest feature wasthe introduction of a “high definition ready” television utilizing a 4:3 screen aspect ratio. Since most of the mediabeing broadcast is still in this format, it was appealing to those who wished to be able to view HDTV if they couldacquire it. It also allowed the viewing of DVD movies in the “anamorphic” state whereby all 480 scan lines couldbe utilized in the active video area while watching a letterbox version and would take advantage of the new 480progressive DVD players entering the market. This would involve a feature known as “16:9 compressed mode”.Vertical scan would be reduced to simulate a 16:9 viewing area on the 4:3 screen.

Since the unit now qualified as “high definition ready”, the horizontal deflection circuits underwent some changesto allow it to operate at 33.4KHZ in addition to 31.5KHZ in order to display 1080i. The video 5 input allowed foreither RGB or component video from a HD source. Although video 4 provides for component input, it will notaccept the 1080i format. Any 1180i format signals received will be directly routed to the video processor. The HDvideo source is unavailable to the multi-image drive circuitry and cannot be viewed in the picture & picture mode.This chassis is unable to process 720p.

Other features included the addition of “V Chip” technology for greater parental control. Due to the ability togenerate three formats (4:3, 16:9 compressed, and 1080i), there are three NVM ICs on the BD board to storeregistration adjustment data. The 3D comb filter has been moved from the A board to the BA board, whichmounts to the A board and also contains the A/D converter

Since the power supply and deflection circuits are virtually identical with the RA-4 chassis, Chapters 8, 9, 10, and11 in this manual will provide the necessary information to service these circuits should the need arise. Thevideo path is similar to the RA-4 but has enough differences to warrant different approaches to isolate videoproblems.

64

14. RA-4A Video Circuit Troubleshooting

Chapter 14 - RA-4A Video Circuit Troubleshooting

IC515A/V

SWITCH

TU501MAIN

TUNER

TU502SUB

TUNER

COMPOSITEAND S VIDEO

1 - 4

CM501GLASSCOMB

SUBYC

IC1301SUB

CHROMADECODER

IC1401SUB VCHIP

SUB CYUV

IC1302YUV SWPIP OSD

MIX

SUB YSUB Y

MAIN Y/COMP

MAINC

IC1305MAIN

CHROMADECODER

IC1307YUV SWCCD MIX

C

BRBOARD

YUV

IC1008MAINCPU

IC24023D COMBFILTER

MAIN YMAIN Y

YUV

BMBOARD

CCD + V CHIP OSD

Y FOR V CHIP

RGBBUFFER

IC511VIDEO

PROCESSOR

IC1004OSD

PROCESSOR

VIDEO 5DTV

INPUT

DTV YUV

RGB

MAINYUV

PIPYUV

CVFORPIPOSDYUV

RGB

RGBTOTUBES

VIDEO 4COMPONENT

FIGURE 14-1 - RA-4A VIDEO PATH BLOCK

BA BOARD

IC1403MAIN YUVSELECT

RGB

PJEDOSD

6/24/0214.1TVP14

As illustrated in Figure 14-1, many of the same processes are performed to the incoming video signals. Allcomposite and S video sources are routed through the 3D comb filter and chroma decoder for the main videosignal. The sub video will pass through a glass comb filter and sub decoder. This will provide the necessarysources for P & P processing for the multi image driver. The main video source will continue on to the BR boardwhere the DRC circuitry will perform line doubling for 960i display.Video 4 input allows non-HD component video to bypass the decoder and comb filter for line doubling by theDRC. Although the video 5 input illustrated in Figure 14-1 appears to head directly to the video processor IC511,non-1080i signals are still sent through the DRCTM by switching the signal out of IC511 to the DRCTM and back bydetecting the sync frequency of the source. This is illustrated in Figure 14-2. This allows for direct processing of1080i sources by the video processor. If the main CPU IC1008 detects a 480i signal source from video 5, it willinstruct IC511 to route the video to IC1403. The CPU will toggle the signal to IC1307. It will then be sent to theBR board for line doubling.

The main CPU IC1008 will generate closed caption, XDS and V chip graphics for display to the main video.Parental control of the sub video path will be provided by IC1401.

65


V4YUV

INPUT

IC1403MAIN YUVSELECT

IC1307MAIN YUV

SW

IC1303SW

IC1008MAIN CPU

DTVSYNC

V5DTV

INPUT

IC511VIDEO PROCESSOR

YUV

H + V SYNCTO DEFLECTIONCIRCUITS

TO TUBES

12 H SYNCO720PFROMOSD CPUIC1009/61

TO IC515FOR AUDIOSWITCHING

IVPODTV

VIN

Y

Y Y

FIGURE 14-2 - DTV VIDEO PROCESSING BLOCK

YUV

Y

480ITOBR BOARD

YUV

6/17/0214.2TVP14

Troubleshooting a “No Video” ConditionUsing the block diagram in Figure 14-1 provides an excellent overall view of the stages of video processing toutilize the various features of this chassis to assist in localizing failures. Since this chassis has four additionalboards attached to the A board, the steps to follow are needed just to find which board is causing the problem!

Verify the presence of high voltage and that no AKB error is occurring. If there is a high voltage problem, refer tochapter 12 of the RA-4 chassis dealing with this circuit. If the unit is indicating an AKB error, refer to Chapter 27.Once the presence of high voltage has been verified, and the AKB circuit is not displaying an error, press themenu button on the remote to see if OSD will display. The ability to generate OSD helps to indicate the videoprocess IC511 is probably functioning properly.

The Picture & Picture feature provided by the BM board will assist in localizing the area in which the signal isbeing lost. Since this circuit has the ability to display the main and sub video sources simultaneously, it isvaluable as a first step. The main path video should appear in the right box and the sub video in the left. EngageP&P with the remote and determine where the fault lies based on the following results on the screen:

Video Appears In Both Boxes: The main and sub video process paths are working correctly. The MID is sendingthe video directly into IC511. The problem is likely located on the BR board. This is the only time in which non-HD sources bypass the DRC. The DRC circuit on this board is constantly running and not controlled by the I²Cbus. IC511 controls the selection of the video source. If video signals are present at pins 67, 69 and 69 of IC511,replace IC511. No signals at these pins indicate the BR board is not sending up-converted video. Check to seeif video is entering the BR board and the 3.3V and 5V lines are OK. If they are present, replace the BR board. Itis not serviceable.

Video Appears In Left Box Only: The sub video path is OK. Once again, the DRCTM is bypassed. This leaves asmall number of components to check. Begin working your way back from the YUV switch, IC1307. Scope thevideo signal path back through the main decoder, and on to the BA board containing the 3D comb filter and A/Dconverter. If the signal is present there, check A/V switch IC515.

66


Gray Background Appears With Two Black Boxes: IC511 is OK. This signal is generated by the MIDTM. The mainand sub video paths are not working. Since a failure in both paths at the same time is unlikely, suspect A/Vswitch, IC515 or a crack in the board.

Screen Is Still Blank: This leaves IC511 as the likely cause. It is not able to process video from either of the inputsfrom the MIDTM or DRCTM circuits. IC511 is getting B+ because high voltage is working. There is no need tocheck the RGB output path to the CRT boards. Since the unit is not showing AKB problems, the IK pulses aregetting to the CRT’s via this path. Check to make the YS/YM line at pin 49 of IC511 is low. This line is used toswitch video off behind PIP boxes and reduce background video when the menu is called up. If it is stuck high,all video will be blanked.

Troubleshooting Video Distortion and Level ProblemsThe procedure for localizing the problem is very much the same as locating missing video. The idea is to narrowdown the area in which the problem is present. With the introduction of multiple A/D and D/A converters anddigital processing circuits, noise in the video is likely to be more common and can take on some strange symptoms.Fortunately, most digital noise problems have a distinct digital appearance. They may be stationary on thescreen or move around in a clock-like stepping motion. Minor or severe loss of picture detail is caused by one ormore of the parallel bit lines being inactive. The more significant the bit, the more detail loss will occur. Powersupply and external noise will “float” since they are not synchronized with the video.

Video level variances are confined to the analog circuits of the set. If all functions are too high or too low, thevideo processor is the cause. Watch the ABL line at pin 44 of pin of IC511. It should be around 2.5VDC with awhite screen. A significantly lower voltage indicates a problem in the ABL pull up circuit. Make sure that YS/YMat pin 49 is not locked at 2.5 to 3VDC. A quick way to eliminate these is to engage the customer menu. Its videolevel is not affected by ABL or YS/YM. If is bright as compared to active video, IC511 is probably OK

67

1. Features

Chapter 15 - Troubleshooting the RA-5A Chassis

OverviewThe RA-5A chassis is Sony’s first high definition, 16:9 aspect ratio, rear projection television to incorporate a DTVtuner and decoder as an integrated part of the chassis. This tuner/decoder assembly is known as the “Q Box”. Itcontains a HDTV tuner, MPEG2 and Digital Dolby® decoding circuits, along with the DRCTM (Digital RealityCreator) and the MIDTM (Multi-image Driver). Video inputs 5 and 6 also allow HDTV signal sources from externaldevices such as satellite or third party HD receivers to be hooked up to the unit.

The set is able to receive all current forms of analog and HDTV signals, including 720P. The horizontal deflectionstage is designed to run at a fixed frequency of 33.75KHZ. All non-HD incoming video signals are line doubled bythe DRCTM to 960i. Since 960i only requires a scan rate of 31.5KHZ, the MIDTM circuits will place the 960 inter-laced lines inside of the fixed 1080i scan rate. The remaining 120 unused lines (60 above and 60 below) will bemoved into the over-scan area by increasing vertical size. 480p sources are converted to 960i by the MIDTM

circuit and inserted into the 1080i fields in the same manner. 720p is converted to 1080i by the MIDTM.

The power supply is of a new design Power supplies would be a better term to use, as there are four of them: Astandby, primary, secondary and high voltage control. A new troubleshooting approach will be necessary since afailure in the primary supply will keep the secondary supply from operating. This will be covered in Chapter 16.

IEEE1394 (ILINK ®) ports are included at the rear with 200Mb throughput. The Q-Box also contains a slot for amemory stick to provide firmware upgrades for the decoder circuits if needed. The CRT driver ICs are a newdesign, extending the bandwidth to 32MHZ in order to reproduce 1080i video resolutions with more detail.

For a more detailed description of the features and circuits, refer to the C29P12 training manual (P/N C29P120901).

68

16. RA-5A Power Supply Troubleshooting

Chapter 16 - RA-5A Power Supply Troubleshooting

5

6

1

2

3

4

8

7

6

5

ACINPUT

IC6106MM1476AF

GND

VINVOUT

GND

C6179

C6137+

+

+

+

+

+

R6060

R6064

R6112

R6111

PH6004

TH6001

D6015

R6065

R6067Q6010

FROM 6.5V PRIMARYSUPPLY

D6017

C6023R6059R6062

C6065

C6072D6016

UDZS-12B

R60574.7 1/4W

C6024

STANDBY5V

FIGURE16-1 - RA-5A CHASSIS STANDBY SUPPLY

TO Q6105, Q6119RELAY LATCH

16.1TVP14 1467 7/11/02

3

1

10

7

1.2Vp-p2ms/DIV

OverviewThe standby power supply has been changed from a switch-mode to a conventional, analog type. Althoughsimple to troubleshoot, it will be covered since it contains an OVP monitoring circuit that can cause the unit toshut down.

The necessary operating voltages at power on have been divided between two switch-mode power supplies,both located on the G board. They are very similar in design to the power supplies in the DX-1A chassis utilizedin the KV31/36XBR400 models. They are appropriately known as the main and secondary supplies. The mainsupply must be operational for the secondary to function. It generates a 20VDC source known as VCC toprovide one of the necessary voltages for the secondary to operate.

Several voltage lines generated by these supplies are monitored for over-voltage and over-current conditions.These will cause the unit to shut down without any indications from the diagnostics feature. Several photo-optical devices are used to latch certain lines to turn off the main relay or stop the oscillators from running. Thesewill be covered in Chapter 17.

Standby Power SupplyAs illustrated in Figure 16-1, the standby power supply is rather unique in that the incoming AC voltage is rectifiedbefore being applied to the primary side of T6003. The DC pulses from the rectifier are used to fluctuate thecurrent in the primary winding. The secondary supplies unregulated B+ to 5V regulator IC6106. Zener diodeD6016 monitors the rectified AC for excessive voltage. If the voltage at the divider consisting of R6065 andR6067 rises above 12V, Q6010 will turn on. The LED inside PH6004 will light and cause the phototransistor tooutput a high to the main AC relay latch circuit to shut the unit down.

Primary Power SupplyThis power supply consists of a self-running oscillator circuit and is not dependent on feedback to function. Oncethe required voltages are input, square waves will be output by pins 12 and 16 of IC6002 as shown in Figure 16-2. They will provide the necessary switching to the driver transistors Q6008 and Q6009. These square waveswill be 50/50 duty cycle and 180° out of phase so that one drive transistor is on while the other is off. Thefrequency of the drive signals controls output voltages from the secondary lines.

69


PH6005OPTICAL

ISOLATOR

NCH

NCH

IC6002DRIVER

MCZ3001D

16

12

9

15

18

26 8 10 14

1

2

C6099

1

IC6107ERROR DET.

uPC1093C31

ACRECT.+FROM

IC6001/1(D BD.)

R60990.47 OHMS

R6007R6098

R6097

R6096

R6092

C6093

VC1 VC2 VB F/B

OCP

R6095+

+

T6004

Q6008

Q6007

TIMER

R6084

R6083

R6163

R6164

D6130

C6017

6.5VSOURCE

D6115

D6183

7V SOURCE

11VSOURCE

VSENSE

FIGURE 16-2 - PRIMARY POWER SUPPLY RA-5A CHASSIS

340VDC

160V

3V

1.86V

D6007

18.4V

4

2

15

10

11

14

14

11

6

7

C6045

R6165

C6116

R6162

D6050

D6048

D6051 D6049

C6086

C6085Vcc TOIC6001/PIN 8

R6082

R6081

16.2TVP14 1465 6/13/02

A BOARD

Activating the oscillator is accomplished by closing the main power relay RY6001 when the set is turned on. Thiswill provide approximately 340VDC to Q6008, a startup voltage to pin 18 of IC6002 along with a sample of theunregulated B+ to pin1. Once the IC receives voltage at pin18 and the divided-down sample at pin 1 is 1.7VDCor greater, the oscillator will run and output drive signals as long as the incoming AC voltage is higher than70VAC.

When pin 16 of IC6002 is high, Q6008 will conduct and send the unregulated B+ to the primary of T6004.Current will flow and charge C6017 through R6083 and R6084. Q6009 is off at this time due to the low at its gate.Once the drive signals reverse phase, Q6009 will turn on and discharge C6017 while Q6008 is off. Current ismonitored at R6083 and R6084 and input to pin 9 of IC6002. The voltage at this point is zero under normaloperating conditions. A rise above .2V causes the oscillator to run at high frequency. Since the shift to highfrequency may alleviate the over-current condition, a fluctuation of normal to high frequency bursts can occur.

Regulation is accomplished by monitoring the 6.5V source at the secondary by IC6107. The voltage monitoredat pin 1 is inverted at pin 3. The pull-down of the cathode of the LED inside PH6005 will control light output to thephototransistor. This will be output at pin 1 and sent to IC6002 pin 2. Any rise in the 6.5V line will cause thephototransistor to pull down IC6002 pin 2, causing the oscillator frequency to increase.

Soft start is accomplished by keeping the oscillator at a high frequency during initial turn-on. This minimizes theinitial current surge by charging filters. The charging of C6093 at pin 6 of IC6002 initiates the soft start andreduces the initial AC current approximately 50%. This initial current limiting, combined with the durability of theFET drivers, allows the supply to survive direct shorts on the secondary lines before the protect circuits react.Once the oscillator is running, it will provide power to itself via pin 6 of T6004. This voltage is rectified and filteredto supply 20VDC to pin 8 of IC6002 and place the oscillator in full running condition. This same voltage willcontinue on to the secondary supply and will become one of the “must haves” for it to operate.

70


Troubleshooting the Primary SupplySince this supply is the starting point for the operation of all necessary power supply operating voltages, it cangenerate erroneous symptoms that could lead a technician in the wrong direction. The secondary supply isdependent on the primary supply running. Technicians usually check for 135V B+ at the start because a testpoint is easy to locate at the horizontal output transistor. That might lead the technician to start troubleshootingthe secondary supply first. The unit will go into shutdown if the primary supply fails to run and can possiblygenerate a diagnostics failure indication. The 6.5V source is monitored for OVP and OCP. The transistors thatperform this task are supplied by standby 5V. It is possible for the 6.5V OCP to engage because of the design.Wasted time would be spent working in the shutdown circuits. It would be wise to always check the primarysupply for proper operation before proceeding with any unit that will not remain on.Verifying Primary Supply Operation: A quick way to verify the primary supply is starting is to listen for two rapidrelay clicks at turn on. They should be less than a half second apart. The first click is the main relay, RY6001 andthe second the inrush current relay, RY6002. If they are distinguishable, the primary supply is starting since itsupplies the 6.5V source to RY6002. If two clicks are heard with one or more seconds in between, the unit isshutting down because RY6002 is not engaging. Check RY602 for continuity and if OK, the primary supplyneeds to be checked. It would also be wise to monitor AC current while performing this check. A current surgeof 3 amps or more will further verify a primary supply startup and signify the presence of an over-current problem.

Dead Primary Supply: If RY6002 does not engage and AC amperage is low or unreadable, the supply is notturning on. Verify the presence of unregulated B+ at Q6008 drain. If not present, check for open R6099 andshorted drivers. IC6002 will oscillate and send output pulses from pins 12 and 16 as long as certain conditionsare met: There must be a startup voltage at pin 18, which is derived from unregulated B+, and the V sense at pin1 is higher than 1.7VDC. The V sense is used to monitor for low unregulated B+, so the AC input should behigher than 70VAC. It is normally 2.5VDC at 120VAC. The oscillator cannot start below 70VAC.

The old method of jumping the main relay and bringing up the AC voltage with a variac will not work in this powersupply design. Even with the main relay jumped and an external DC source applied to the V Sense line, theoscillator will not start until at least 70VAC is reached. At the 70VAC level, the oscillator will start and stop at one-second intervals. The horizontal and vertical deflection circuits will start and stop. The rise and collapse of thedeflection will burn the phosphors in the tubes if they are lit. Do not attempt to run the supply at lessthan 80VAC. Always disconnect the CRT sockets when working this power supply.

As mentioned earlier, this power supply design is extremely durable and can survive a startup with a direct shorton any of the secondary lines. As long as measurements are made for static shorts on the secondary lines, thesupply can be started at full AC. It will stop oscillating on its own or the unit will go into protect mode if a problemstill exists. AC current draw will still need to be monitored at turn-on to provide an indication of what step to takeif there is still a problem. Normal AC current draw for this chassis is between 1.3A and 1.8A, depending on ACline voltage and picture brightness. With 120VAC and color bars in the Vivid Mode, the unit draws 1.5A.

With a no-start condition verified, perform the following checks:

No Drive Signals Being Output: Unload the output pins. If oscillation is present, suspect loading from themultiple protect diodes (not shown in Figure 16-2) present on these lines. This can happen if the drivers(Q6008/6009) were originally shorted. If drive pulses do not appear, suspect faulty IC6002.Drive SignalsPresent: Connect a scope to pin 2 of T6004 and observe for square drive pulses at roughly twice theamplitude of the AC input voltage. Suspect open Q6008 or components driving the gate if not present.Check the voltage at pin 9 of IC6002. If any voltage above .2VDC appears, R6083 and R6084 haveopened. If no voltage appears, suspect open C6017 or T6004 primary winding.

Dead Supply. Switching Transistors Shorted: A more cautious approach must be taken when this occurs.There is slight possibility that excessive current caused this failure – and an even higher possibility thatline transients caused them to fail. The loss of a newly installed set is not only frustrating, but costly inparts and time wasted. Static resistance readings of the secondary lines to ground are the first order of

71


business. This supply has ± supply rails, so do not forget to read across them for low resistance readings.A quick visual check for overheated components is also a good idea. Check for open fuse links on thesecondary lines, as these are valuable clues. If the above items check OK, the supply can now bestarted.

Primary Supply Starts - Unit Shuts Down: Two rapid relay clicks are heard followed by a third click one to severalseconds later. The big question is whether the problem is in the primary supply. The unit is shutting down andmany other areas can be the cause. A good way to approach this situation is to monitor AC current draw.

Low AC Current Draw: If it is low at power up, check the 6.5V source generated by the primary supplyduring initial turn on. Troubleshoot the regulation stage if it is too high. If it is significantly low, theregulation circuit may be at fault or the oscillator is staying in startup mode due to loss of VC1 at pin 8 ofIC6002. This line is protected by fusible resistor R6082.

High AC Current Draw: In order to isolate this condition to the primary supply, disable the secondarysupply by grounding pin 1 of IC6001. Although the unit will still shut down, the loss of high AC current willeliminate the primary supply as the source. If high current draw remains, the failure is isolated to theprimary. Chapter 17 will deal with shutdown problems.

Regulation Problems: Since the diagnostics circuits monitor the 6.5V source for OVP, problems in this circuit canbe isolated quickly. Verify a legitimate problem by measuring the 6.5V at turn on. If it stays at 6.5V, suspect afaulty zener diode D6133 or Q6110, Q6111 and associated components. If the over-voltage condition is occurring,locating the component is done by grounding pin 2 of IC6002. This should bring the 6.5V line below its normalvoltage by forcing the oscillator to a higher frequency. If not, IC6002 is faulty. If the 6.5V source drops, work yourway back by grounding pin 1 of PH6005 followed by pin 3 of IC6107. Grounding any one of these lines shouldbring the 6.5V below normal level. If grounding these points does not reduce the voltage, the problem is likelyone of the sampling resistors (R6162 or R6163). Error amps such as IC6107 are very reliable and should besuspected least.

Secondary Power SupplyThe operation of the secondary supply is virtually identical to that of the primary, as shown in Figure 16-3. Itgenerates the higher voltages in the set and drives two transformers instead of one. The sources needed to turnit on are different from the primary. It requires unregulated B+ like the primary but the startup line at pin 18 ofIC6001 is not used. The V sense line is still used to monitor unregulated input. It is also used to control theoscillator on via a high from the VCC line. A main SW high from IC001on the B board controls this line. It is alsocontrolled by latch transistors Q6004 and Q6005 for protection. VC1 at pin 8 is supplied by the primary supply toprovide the oscillator with its operating voltage. This is why the secondary supply cannot operate without theprimary running.Regulation is controlled by monitoring the 135V line instead of 6.5V. Two transformers are driven T6001 PIT andT6002 PIT AUX.

72


VSENSE

1

IC6001DRIVER

MCZ3001D

16

12

9

8

15

18

14

10

2 PH6002OPTICAL

ISOLATOR

4

2

IC6101CONTROL

DM-585

4

1

PRIMARYPOWERSUPPLY

AC

ACD6530

DC

T6002PIT-AUR6041

0.1 OHM

R6013

R6015Q6507

Q6001

N

Q6002N

R6022

D6502

R6O70

VC2

VC1

V B

OCP

Q6003

R6033

P

R6035

Q6506

R6052

R6590

NCH

NCH

D6104

R6021

FIGURE 16-3 - SECONDARY POWER SUPPLY RA-5A CHASSIS

1

9

12

10

9

11

15

14

8

9

10

13

7

2

4

1

3

R6017

R6014

7

Vcc

R6055

R6073

R6074 R6054Vcc

NO CONNECTION

VD

FROMMAINSW.

PH6003

R6056

D6107

L6106135V

SOURCE

C6022

C6028

C6033

C6034

D6116-19V

+19V

-15V

+15V

-22V

+22V

AUDIOGROUND

D6105

D6108D6117

T6001PIT

STBY5V

SS

PS101

PS102

PS103

PS104

16.3TVP14 1466 6/13/02

D BOARD

Troubleshooting the Secondary SupplyOnce the primary supply has been proven to be operating correctly, the diagnostics checks are similar to servicingthe primary supply. As long as there is confirmation of no problems in the primary circuits, the main AC relayRY6001 can be jumped and power applied with the variac. AC current and the 135V line voltage must bemonitored closely. By monitoring AC current and the 135V line, the results will designate where to proceed.

AC Current Less Than 1.5A, 135V OK: Loss of ±15V or ±22V supplies has occurred. These lines are monitoredby the protect circuits.

AC Current Less Than 1.5A, 135V line too high: Troubleshoot regulator loop as outlined in primary supplyprocedures.

AC Current Exceeds 3A at low AC input: There is a short or excessive dynamic load. Disable secondary lines toisolate. If secondary lines check OK, suspect leaking coupling capacitors C6033/34 at T6001 or C6022/28 atT6002, or defective transformers.

73

17. RA-5A Protect Circuit Troubleshooting

Chapter 17 - RA-5A Protect Circuit TroubleshootingOverview

As illustrated in Figure 17-1, several circuits are monitored for protection. Some lines are monitored by the self-diagnostics feature while others are not. The self-diagnostics feature can assist in isolating a particular circuit.Below is an example of the diagnostics page which is entered by pressing “DISPLAY”, “5”, “VOL –”, and “POWER”:

Self Check

2: +B OCP 00

3: +B OVP 00

4: V Stop 00

5: AKB 00

6: Low B 00

7. H STOP 00

101: WDT 00

The numbers on the left indicate how many times the timer LED flashed, which designates the probable cause ofthe shutdown. The flashes on the LED will occur at one second intervals, followed by a three second separationperiod and repeat again. The numbers at the extreme right indicate how many times the problem occurred up to99 events. You can see why this is beneficial for intermittent troubleshooting. It is always a good idea to clear theevents before exiting and that can be done by pressing “8” “enter” on the remote. This is not the same aspressing these buttons in the service mode. It will only clear the events and not reset customer defaults. Bewarethat the service manual instructs you to enter the service mode to clear these and that is a mistake. You can doit right from this screen. Let us briefly cover each one.

+B OCP: Excessive current on the 135V line. This is usually caused by flyback problems or secondary loads onthe line. The circuit could also be tripping for no reason. This is why you should always monitor AC current whilethe unit is shutting down. It will help to know if you are really dealing with an over-current condition and a morecautious approach can be taken while troubleshooting.

+B OVP: The 135V line has exceeded 139 volts. Go back to Chapter 16 on troubleshooting regulator problems.

V Stop: The vertical deflection circuit has stopped operating. Loads on the I2C data and clock bus can also bethe source of this problem.


Low B: The 6.5V source from the primary power supply is monitored for excessive voltage and current. Thisdiagnostic label can be misleading because an OVP condition on this line will also register a failure.

H Stop: Horizontal deflection has failed. Since the unit has a separate high voltage circuit, the set will shut downto protect the CRTs. This will be covered in Chapter 18.


74


POWEROFF

LATCH

15VOVP

IC3006VIDEO

PROCESSOR

22VOCP

AC INOVP

+135VOCP

SUB6.5VOVPOCP

IC001MAIN MICRO

C246X

+135VOCP

A25 C25 C26 B19 A20

8

7

5

4

76

0X

0X

0X

3X

2X

R IK

G IK

B IK

2

2

29

STANDBY LED

(HA BD.)

ACRELAY

POWERON/OFF

IK5X

B BD.

CN013/CN3022

S DATA S CLK

OVP

OCP

CN6101/CN3016

V LOSS4X

7XH.PULSES

CN3005/CN8004

CN3007/CN8006

CN001/CN3020

CN3011/CN3703

FIGURE 17-1 - PROTECTION BLOCK - RA-5A CHASSIS

6

0.02V

4.6V

0.1V

0.1V

0.2V

19VOCP

AUDIOPROTECT

HVPROTECT

G BOARD

CB BOARD

CG BOARD

CR BOARD

A BOARD D BOARD

17.1TVP14 1464 6/24/02

The above protection circuits have dedicated communications line with IC001. The 135V OCP/OVP, Low B andH Stop have direct connections. V Stop and AKB notify IC001 by way of the video process IC3006, whichannounces the event via the data bus line. The remaining lines have no communication ties with the main CPUIC001. They are:

1. AC In OVP: The unregulated B+ in the standby supply primary is monitored by Q6010 and will turn onPH6004 to activate the protect latch. This is illustrated in Figure 16-1 in Chapter 16…

2. Audio Protect: The speaker lines are monitored for DC component by Q2608, Q2609 and Q2610 on theK board.

3. 15V OVP: Monitored by Q6101 and D6121 as shown in Figure 17-2.

4. 22V OCP: Excessive current on or loss of +22V also monitored by Q6101 and D6126.

5. 19V OCP: This voltage is generated by the secondary supply and monitored by Q6101 via D6122

6. HV Protect: The HV circuit is monitored for excessive HV or current by IC8006 and IC8007 on the Dboard. Troubleshooting this circuit will be covered in Chapter 18.

These monitoring circuits will cause the unit to go into protective shutdown by generating a high signal to thelatch circuit without diagnostic indicators. It has been found that failures in any of the protect circuits can causeprotection event indications in the diagnostics mode. As an example: A HV shutdown will sometimes register anAKB error. It is a good idea not to rely heavily on the diagnostics but to use it as a guide.

75


T6003STANDBY

P.S

23

41

R6119

Q6119

Q6105

D6015

AC INCN6001

R6112100

AC RELAYRY6001 D6001

BRIDGERECT.

STBY 5V

Q6120D6111

C614610

R619547k

R61331k

C6140Q6101P

+15V(SEC P.S.)

D6122AUDIO

PROTECTFROM

K BOARD

D6125

D61265.6V

R61341k

15V OVP22V

OCP (SEC P.S.)

+22V

R6111 100

AC INOVP

STANDBY 5VSOURCE

R6064 2.2kD6017

PH6004

R6132

D612120V

R6065

R6067

D201612V

C6065

CN6101/CN3016

CN3020/CN001

MAIN MICROIC001/69

N

N

P

4 5

C26

FIGURE 17-2 - SHUTDOWN - NO INDICATION - RA - 5A CHASSIS

+

Q6010OVP

HVPROTECT

FROMD BOARD

19V OCP(SEC P.S.)

D3009

+19V

HP DET. (Q3061)VIDEO PROCESSOR

ICIC3006/34

R60602.2k

17.2TVP14 1463 7/11/02

G BOARD

A BOARD

B BOARD

TroubleshootingThe first step is to verify a protection event is occurring. Observing the timer LED for flash sequences is a goodplace to start. The only diagnostic monitoring circuit that will not shut the unit down is AKB (five flashes). If nodiagnostic indications appear, listen for relay clicking sounds. They provide a good indicator as to what directionto approach. On a properly operating unit, two relay clicks will occur less that 500ms apart. The timer LED willflash at one-second intervals until the CRT cathodes return IK pulses and the picture will appear.

No Clicking Of Relays: Look for one-second flashes of the timer LED. If none are present, the standby supply isnot operating or the main CPU IC001 is not operating. If the timer LED flashes at any time, the standby supplyis OK. Suspect problems in the relay drive circuit or the relay RY6001. Verify a high command from IC001, pin69.

One Relay Click Followed By Another At Least One Second Later: Since the two relay clicks occurred more than500ms apart, the unit is going into protect mode. The lack of the rapid clicks indicates RY6002 is not engaging.This is caused by a failure of the relay (which is monitored for protection), or a malfunction in the primary supply.If RY6002 is OK, refer to Chapter 16 on troubleshooting the primary supply.

Two, Rapid Relay Clicks Followed By a Third Click: This symptom provides two valuable clues: The standbysupply and CPU are operating and the primary supply is starting. It may not be staying on, but it is at leaststarting. The unit is going into protect and may or may not display diagnostics indications. Since the self-diagnostic feature tends to lead you in the next direction, troubleshooting a “no Indication” shutdown will becovered next.

76


Shutdown – No Diagnostics IndicationSince RY6001 and RY6002 are engaging, there are the five monitoring circuits mentioned earlier that will causethe unit go into protect as shown in Figure 17-2. Monitoring AC current draw while letting the unit go into protectwill assist in determining whether the failure is current, or voltage related and steer you to the circuits to checkfirst.High Current At Shutdown: If the current peaks at 3A or more, four circuits can cause this: The 19V line in thesecondary supply, the 22V line in the primary supply, an audio problem on the K board, or excessive current and/or high voltage in the HV section. Disconnect CN2103 on the K board. If the unit stays on, there is a problemwith DC on the Speaker lines. Suspect audio output IC2601. If the high current and shutdown still occurs,disable the secondary supply by shorting pin 1 of IC6001 to ground. Although the unit will still shut down, asignificant drop in AC current narrows the problem to the D board or an excessive load on the 19V line. Ifshutdown and high current still exists, excessive loading is present on the +15v line.

Normal Current At Shutdown: This condition points to any one of the six circuits being monitored. A loss ofvoltage on the 19V and 22V line will simulate an OCP condition. Any of the protect components could beactivating due to a malfunction of the components themselves. Since excessive current is not being drawn, therisk of further component damage is minimized while searching for the cause.

CN2103 on the K board should be disconnected first to eliminate the audio circuits. If the shutdown persists,monitor the voltage at pin 7 of IC8006 on the D board. This pin should remain low unless excessive HV hasoccurred. From this point, it becomes a matter of checking voltages on the monitored lines with a peak-holdDVM or oscilloscope.

Shutdown – Diagnostic Indication2X Flashes: Verify a legitimate over-current condition by monitoring AC current at shutdown. If high, disable HVcircuit first, followed by horizontal deflection circuit. Refer to chapter 18 for troubleshooting if either of thesecircuits is found to be the cause.

3X Flashes: Monitor the 135V line with a peak-hold meter. If the voltage peaks above 139V, refer to Chapter 16for troubleshooting regulator problems.

4X Flashes: Check the DC voltage at the clock and data lines at main CPU IC001. The voltage should be4.6VDC. If either is low, locate the component loading the line. If OK, troubleshoot vertical circuits covered inChapter 18.

6X Flashes: The 6.5V source is monitored for excessive current and voltage. Check AC current at shutdown. Ifhigh, begin unloading circuits from line. Most of the circuits using this line are in the Q box assembly so startthere. If current is low, check 6.5V level at turn on. If excessive, troubleshoot regulator stage as covered inChapter 16.

Note: A voltage below 1.7VDC and above 5VDC on the V sense line at pin 1 of IC6002 can generate six timerLED flashes.

7X Flashes: Troubleshoot horizontal deflection circuit covered in Chapter 18. Disconnect the C boards fromthe tubes while working on this circuit.

77

18. RA-5A Deflection Circuit Troubleshooting

Chapter 18 - RA-5A Deflection Circuit Troubleshooting

OverviewThe deflection circuits in the RA-5A chassis are similar to the RA-4/4A chassis in that horizontal sweep and HVare generated in separate circuits. Pincushion correction is performed in a different manner and HV protectionis not monitored as part of the self-diagnostics feature. HV protection is accomplished with fewer componentsunlike the redundant circuits found in the RA-4/4A chassis.

Horizontal Deflection TroubleshootingReferring to Figure 18-1, horizontal sweep is generated in the conventional way using an H pulse from pin 40 ofIC3006 on the A board. It is amplified and transformer coupled to the horizontal output transistor Q8024. Thedeflection yokes and T8003 are driven. T8003 generates 200VDC for the dynamic focus correction circuit and a± 100V source to provide offset of the red and blue deflection yokes for centering to the green CRT. Horizontalcentering control is also provided by IC8012 and Q8039.

IC 8005 is a PWM control device that serves to modulate the horizontal output B+ level to T8003 for pincushioncorrection. The H pulse at pin 14 provides the timing for the sawtooth reference while the E – W signal suppliesthe necessary vertical parabola signal for scan width modulation.

Q8031 and Q8101 buffers and shapes the H pulse for use in OSD timing and, more importantly, tells the Hprotect circuit that horizontal sweep is occurring.

Since there is no flyback transformer incorporated into this circuit, current demands on the horizontal outputtransistor are lower and damage from CRT and flyback arcs are nonexistent. This also makes troubleshootingeasier. Loss of horizontal deflection is likely to occur because of Q8024 failing. It is wise to check Q8027 whenthis happens since it is easily damaged from the large current surge when Q8024 shorts and it also may havebeen the reason for the failure.

Apply full AC power with the variac and watch for the horizontal pulse (assuming it appears). Monitor the ACcurrent level closely while doing this. If the unit is still going into protect mode, this will have to be observedduring the period from startup to shutdown. Clean pulses should appear and be 11 to 13us wide. Any deviationfrom the normal pulse indicates a tuning problem. Suspect T8003 or one of the deflection yokes. If the pulsesare correct and excessive current is being drawn (more than 3 amps), there is a problem in the driver circuit orthe pincushion driver Q8027 is in saturation. The horizontal output transistor will also get hot rather quickly.

Another situation that might occur is that the retrace pulse looks great but begins to jitter and dance on the scopescreen. The AC current will also be higher than normal. This usually indicates excessive loading in the circuit.Look for shorts in the secondary lines of T8003.

Pincushion TroubleshootingThe simplicity of the pin correction circuitry in this chassis should provide easy troubleshooting. The key symptomto observe is whether the picture is stretched or of insufficient width with pincushion distortion.

Picture Too Wide: Q8027 is not modulating the scan width accordingly and is either shorted or in saturation.There should be approximately a 15V difference between the source and the drain. Shorting the gate of Q8027will aid in determining whether IC8005 is overdriving it or the transistor is at fault. If the picture width is substantiallyreduced, check IC8005 for missing H pulse at pin 14 before replacing.

Insufficient Width: Q8027 is open or not receiving pin correction signals. Check for a parabolic signal at thegate. If not present, verify the E –W signal is at pin 6. If it is, check the associated components around IC8005before replacing it. Pay close attention to the components supplying feedback to the operational amplifiers inthis IC. Beware that the NVM IC storing the pincushion correction data has caused problems in some previousmodels.

78


IC8005H DRIVE

CTL

2

3

6

14

T8003HOT

1

4

3

21

H OUT

H RET

1

42

1

3

5

H OUT

H RET

1

4

H OUT

H RET

1

4

T8002HDT

Q8020

Q8016

Q8004

Q8030

Q8023 Q8024H OUT

Q8031

Q8101

H PULSETO A BOARD

Q8039

IC8012

IC8019HLC

C8137

D8032

D8045

DYB

DYR

DYG

H CENT.

+-

+-

Q8027

135V

200V TODF CIRCUITS

FROME-W

IC3006PIN 47

A BOARD

12V D8033

FROMH DRIVEIC3006PIN 40

A BOARD

IC8009

112VDC

+

FIGURE 18-1 - HORIZONTAL DEFLECTION RA-5A CHASSIS 18.1TVP14 1468 7/10/02

Vertical Deflection TroubleshootingNo Vertical Deflection: The first instinct of the technician is to go after the vertical output IC5004 and understandablyso. It is a drive component with heavy current usage and heat dissipation, and it is usually the cause of thefailure.

The first check that you should do (and this applies to all Sony televisions of the last seven years) is to check thevoltage level of the clock and data lines on the I2C bus. They are conveniently labeled SCLK and SDAT. The DCvoltage should not be lower than 4.6 volts. If either of these lines is loaded down, the vertical oscillator will notstart. This is the number one cause of multiple component replacement for a simple vertical problem. Youshould always check the clock and data level whenever you have a strange problem and, particularly, if it appearsthat you more than one problem. Although most television chassis’ will not produce vertical deflection, some willgenerate other symptoms. As an example: The AA-2W used in Sony’s KV32/36XBR200 sets will display amagenta colored raster with no video and insufficient vertical height. Assuming the bus is okay, move onto thenext step.

Since this chassis will go into protect mode and shut the unit down, certain measurements must be taken andwatched for during the time the unit powers up and shuts down. Unlike previous designs, the V stop featurecannot be overridden since pin 35 of IC3006 is looking for vertical feedback ramp pulses from the yoke return.Always remove the C boards from the tubes when servicing a no vertical sweep condition.

The ± 15V lines are the first to check. If OK, place a scope probe and watch for a moment of vertical sawtoothsignal at pin 1 or 7 of IC5004. Any presence of drive signal here indicates IC3006 is generating V drive andisolates the problem to the output circuits. Verify vertical ramp signal on the high side of R8036 or R8039 in thereturn circuit. The circuit could be running and Q8001 is not sending the V signal to IC3006.

79


IC5004V OUT

LA78045

B19

A20

IC3006VIDEO

PROCESSORCXA2150AQ

25

24

52 53

7 1

2

4

35

5

+15V

-15V

FROMSECP.S

(G BD.)

R055

S DATA

R069

STBY LED

AC RELAY(B BD.)

S CLK CN013/CN3022

+ - VDRIVE

V PROTECT

CN3005/CN8006

CN3103/CN5505

3 5 7

FIGURE 18-2 - VERTICAL DEFLECTION RA-5A CHASSIS

B

G

R

R8040220

Q8001BUFF.

R8036

R80392.2

D80015.6V R8015

V DYCN8009CN8008CN8007

3

1

3

1

3

1

18.2TVP14 1462

B BOARD A BOARD

IC001MAIN MICROM306V2MF 26

31

D BOARD

Repeat Vertical Output IC Failure: If IC1509 fails immediately upon replacement or soon thereafter; it is usuallythe fault of C8015. This is the boost capacitor. It charges to almost 30VDC during the lower half of the verticalsweep to provide additional voltage to allow the beam to retrace to the top rapidly. When this filter dries out oropens, the output IC will attempt to accomplish the retrace but the negative feedback line will resist the suddenvoltage kickback from the yoke and the +15V drive will cause the IC to draw excessive current. In smallertelevisions, a boost capacitor failure causes slight loss of vertical at the top with some fold-over.

Insufficient Vertical Height: Either the vertical output IC is being told what height to display and is unable tocomply, or it is receiving erroneous drive information. Due to the nature of the operational amp within IC5004, itis rare for it to not be able to amplify properly. Operational amps have massive amounts of gain, which is whythey need negative feedback to keep them under control. Suspect IC5004 as the last possible cause. Gainproblems can be caused by improper supply voltage (very rare) or problems in the feedback line (more likely).This is why you should always scope the feedback line when height or linearity problems arise. In this chassis,the best point is the top end of the ground return resistors (R8036 or R8039). What should normally be here isapproximately 1VPP of vertical rate sawtooth. If there is a problem, you will observe one of two things: Asignificantly larger sawtooth level or horizontal frequency contamination in the sawtooth. A large sawtooth indicatesone or more of the ground return resistors or the thermal compensator TH8001 has opened. The negativefeedback of the operational amplifier will respond by reducing gain. If there is a large amount of horizontalcomponent in the feedback, the amp will also reduce gain since the average DC level will be higher at thisfrequency. The vertical deflection yoke windings are right next to the horizontal windings so it is very easy toinduce this into the vertical return. Suspect an open C8001 or C8023 at this point.

Should the feedback line check OK, you now have a possible input problem. IC3006 can cause this and it isdifficult to verify without replacing it. Beware that faulty NVM ICs have been known to cause vertical heightproblems.

80

19. RA-5A High Voltage Circuit Troubleshooting

Chapter 19 - RA-5A High Voltage Circuit Troubleshooting

FIGURE 19-1 - HIGH VOLTAGE STAGE - RA-5A CHASSIS

T8005FBT

IC8007PROT. 1

Q8028-9ABL

DRIVERQ8004Q8016Q8019Q8020

H DRIVEQ8023

H OUTREG.Q8027

DRIVERQ8036Q8037

IC8008PWM GEN.

1

10

3

3

C8118 LOTT8004

1

14

12

12

1

62

2 41

HV BLK

7VIDEOOUT B+C B BD.

14

10

10

9

IC3006VIDEO

PROCESS40

7

3

5

IC8006PROT. 2

5

3

2

D8025

D8023

+12V

CN8016

CRTHV

R8171100

+135V

D803615V

MIX OUT TOIC8007

Q8035HV REG.

PCH

CN6106/CN8013

CN8004/CN3005

CN3007/CN8006

V BD.VEL MOD COILS

CN3023/CN9001

CN3010/CN9001

CN3001/CN9001

+135VSEC.P.SIC6001(G BD.)

D8039200V

R8219

D8038

R8223

CN8022/CN7304

D8029D8030

C8142

ABL

RR8153 PROT.VR8002

100kD8017

N

D803118V

D8034

D8035R8160

R819810k

Q8021

Q8022

DRIVERSQ8005,Q8032

+15V CN8021

A BD.

G BD.

D BD.

Q8038HV OUT

D BD.

+135V

+135V

7/17/0219.1TVP14

111

200V TO

R8196

8.1V

7.46VDC

7

11

S

D

G

D8015LATCH

18

6

VR80015kHV

1

1

OverviewFigure 19-1 illustrates a block diagram to give an overall view of the circuitry on the D board for generating highvoltage. The main components consist of a regulator stage to vary the B+ level to the flyback transformer for HVlevel control, a driver and output stage to switch the flyback on and off, a flyback transformer to generate HV anda LOT transformer to generate heater voltage and 200VDC for CRT cathode bias.

IC8008 is a PWM generator and driver to control the on and off time of HV regulator Q8035. The sawtoothwaveform for the PWM generator is synchronized to the horizontal drive pulse at pin 14 to provide a stablereference. A sample of HV level is taken from the HV block assembly and enters pin 12 to provide an error loopby which to vary the duty cycle of the drive pulses to Q8035. Q8038 provides the necessary switching to turnT8004 and T8005 on and off and maintain a HV level of 31KV.

HV level and current are monitored by IC8006 and IC8007. They will stop high voltage generation to provideprotection for the HV components, CRT’s and X radiation level. This is accomplished by disabling the H drivepulse from video process IC3006. Both the HV level and shutdown threshold are shown as adjustable byVR8001 and VR8002 but these controls are sealed with epoxy at the factory and are not adjustable.

81


TroubleshootingHigh voltage circuit failures generally fall into four categories: No HV, low HV, excessive HV and excessivecurrent. The latter two will cause the HV circuit to cease operating and, depending on which protect IC detectedthe problem, may shut the entire set down. Since the HV protect circuits are not monitored by the self-diagnosticsfeature, conventional procedures are needed to perform the initial diagnosis.

Dead HV Circuit: The initial concern with this symptom is whether the HV output Q8038 has shorted. This will beevident by the fuse link being open on the 135V line. If Q8038 is not shorted, it is important to be certain the highvoltage did not come on and shut off suddenly. In extreme situations, HV shutdown can occur so fast that itappears to have never started. A quick check of pin 7 of IC8007 for a high will confirm a shutdown since D8016latches the IC. IC8006 pin 7 also latches but, unfortunately, outputs to the main relay latch circuit and will shutthe unit down. A peak-hold DVM or oscilloscope will be needed to catch the momentary high output. Once it isconfirmed the HV is not starting, a dead HV circuit will be caused by a shorted HV output or a malfunctioningcircuit. The approach for either reason will be different.

No HV – Q8038 Shorted: Verify Q8035 is also not shorted. It may have failed after the fact or could bethe reason for Q8038 shorting. The extremely functional soft start circuit in the power supply will provideenough current limitation to prevent a repeat failure of Q8038 in most cases. If the HV regulator ismalfunctioning or there is excessive current draw, the HV or 135V protect circuits will activate during thesoft start period. If the unit shuts down after replacing shorted components, the HV circuit will need to bemonitored to locate the cause.

Place your scope probe somewhere near the HV output transistor or flyback. Most scope probes are notable to handle the direct spike level from the flyback so this is a safe method. Just turn up the gain a littleon the scope and you will easily see the retrace pulse. Connect a DVM to CN8016 and monitor the DCvoltage. It must not rise above 7.5VDC, which would signal a HV regulator problem. Apply full AC powerwith the variac and watch for the pulses (assuming it appears). You are going to have to attempt toobserve them during the startup and shutdown duration. If the flyback is defective, one of two waveformsis likely to appear. The first may look like a sinusoidal waveform with a distinct ringing appearance. Thisdefinitely indicates flyback problems. The second phenomenon will be a retrace pulse with a second,lower level, “phantom” pulse, which also indicates a defective flyback. If the retrace pulse looks great butit begins to jitter and dance on the scope screen, this usually indicates excessive loading of secondarylines. In this unit, it can be loads on T8004. Measure for shorts on the filament and 200V line. Theflyback transformer T8003 only has two load circuits and they are the HV and focus blocks.

Do not worry about excessive high voltage problems. If the high voltage rises too high, the horizontaldrive pulse will be cut off, the circuit will stop functioning and the unit may go into shutdown. If the pulsestill looks good by the time the circuit activates, you are good to go. If it goes into HV protect, proceed toHV shutdown section to follow.

No HV – Q8038 Not Shorted: Check for 135VDC at Q8038-C. This will verify proper operation of the HVregulator stage. Since the unit is not shutting down and generating an H Stop event in the diagnostics,horizontal drive is being output by IC3006. Work your way back from Q8038 to locate where the drivesignal is being lost.

If the voltage at Q8038-C is extremely low or missing, the HV regulator is at fault. Check pin 3 of IC8008.There should be 12VPP pulses with a long duration positive pulse. This indicates the PWM driver isattempting to get proper HV and Q8035 is unable to amplify. If pulses are not present, IC8008 is notworking properly. Verify 12VDC at pin 1 and H pulses at pin 14 before replacing IC8008.

High Voltage Too Low: This is not a common occurrence in this circuit design. PWM regulators will generate lowvoltages if the reference sawtooth frequency or level changes or if the error loop voltage rises due to pull-downresistors increasing in value. The saw reference is locked to the incoming H pulse and the level is controlledinside IC8008. A quick method to isolate the cause is to measure the voltage at pin 12 of IC8008. If it is higher

82


than 7.5V, the HV block is defective. If it is significantly lower, check the PWM signal at pin 3. If the positive dutycycle exceeds the negative, IC8008 is sensing the low HV and trying to compensate. Check for clean pulses atQ8038-C. If they are OK, the HV block is defective.

If the negative duty cycle exceeds the positive, IC8008 may be defective. If the duty cycle is near 50%, someonehas managed to turn VR8001 out of adjustment.

High Voltage Shutdown: Verification of an over-voltage or over-current condition must be checked first. Monitorthe AC current draw at shutdown to determine which is causing the condition.

Excessive Current: If the AC current exceeds 2A or more immediately at turn-on, begin by disconnecting the HVblock from the circuit. The circuit will still shut down since the error loop for the PWM has been removed, but thecurrent level will drop significantly if the block is defective. If the current remains excessive, check for shorts onthe filament or 200V line. T8004 or T8005 could be defective and can be tested by following the procedures inthe previous section on replacing a shorted Q8038.

Nominal Current: Either the high voltage level has exceeded acceptable limits or the protect circuits are activatingerroneously. Verify Q8035 is not shorted. The HV block has an extra output port for testing the HV level. Simplyremove the cap and insert a HV probe. This is a very important step. If the high voltage level is excessive, extracaution must be taken while diagnosing the circuit. Due to the small size of a projection CRT, it is easy for thehigh voltage to exit the anode cap and arc to the deflection yoke. This usually cracks the CRT. Turn the set onand watch the HV meter for a reading before the unit shuts down. Normal HV should read 31± .40KV. A properlyfunctioning and adjusted protect circuit will trip at 34.5± .50KV so you should be able to see this with the probe.

High Voltage Exceeds 35KV: Connect a DVM with peak-hold to pin 12 of IC8008. The voltage shouldread approximately 7.5VDC. A peak voltage of 7.5V or less indicates a defective HV block or IC8008 isloading the feedback line. If the voltage level exceeds 7.5V by a considerable amount, the feedback loopfrom the HV block is OK and the PWM generator is not operating properly, or the tuning components atQ8034 are defective.

To isolate the problem, take a peak reading at the output (drain) of Q8035. If the PWM circuit is operatingproperly, the voltage should be substantially less than the 135V supply. This indicates the PWM circuit isattempting to reduce the HV level. Suspect an open C8123 or C8124 (not shown) at Q8034-C. Fullvoltage at the input and output of Q8035 indicates a short or leakage of this component or an improperlyoperating PWM circuit. Check VR8001 for resistance at the contact wiper to both ends, along with areading from end to end. If this VR fails, the high voltage will rise to maximum potential.

High Voltage Reads Approximately 31.5KV: The regulator stage is assumed to be working correctly. Theprotect components are inappropriately firing. If the unit is going into full shutdown, troubleshoot IC8006and its associated components. If the unit is only shutting down the HV circuit, check IC8007 and itscomponents. As illustrated in Figure 19-2, both IC8006 and IC8007 use a 5.1VDC reference at pins 2and 6. Pin 3 of IC8006 monitors a voltage sample of T8005. Pin 3 of IC8007 monitors a HV block samplefrom PWM IC8008. FBT ABL is monitored by Q8028 and Q8029. These transistors are normally onunless FB current becomes excessive and the ABL voltage approaches zero volts.

Check for proper reference level if 5.1V at the inverting inputs of both ICs. If OK, check for voltages at thenon-inverting inputs that exceed 5.1V. If none exceed 5.1V and pin 7 of either IC is high, replace the IC.

83


5

67

+-

3

21

+-

5

67

+-

3

21

+-

D8014MTZJ-5.18

D8013MTZJ-5.18

RV8002

R8102

R8223

R8153

FBTABL

D8038R8099

R8139+15V

FBTABL

R8151

R8157

R8150

R8141+15V

Q8029

Q8028

IC8007

IC8006

D8025D8015

D8023D8016

D8008Q8022

Q8021

R8138

R8142

+15V

+15V

D8043

R8128

TO MAINRELAY LATCH

PROTECT

H PULSELATCH

HVBLOCKSAMPLEFROMIC8008

T8005SAMPLE

FIGURE 19-2 - HV PROTECT CIRCUITS RA-5A CHASSIS 19.2TVP14 1469 6/11/02

84

20. RA-5A Video Path Troubleshooting

Chapter 20 - RA-5A Video Path Troubleshooting

OverviewThe RA-5A chassis incorporates a DTV tuner and decoder circuits in a shielded board known as the “Q Box”.MPEG2 decoding of ATSC broadcast signals along with Digital Dolby® decoding circuitry allows for reception ofall current formats. The DRCTM and MIDTM process circuits are located on this board along with an OSD generatorto display the customer menu along with certain HD setup information. An overall view of the video paths can beseen in Figure 20-1. An important point to remember is that all video signals pass through the Q Box beforebeing sent to the video process IC3008. The Q Box is not serviceable and must be replaced as a unit.

The B board contains the necessary switching and processing circuitry for both analog tuners and all of theexternal input lines. The Q Box is mounted to this board. The main microprocessor IC001 is also located on theB board and supplies service data OSD to the video processor.

The A board contains the video process IC3006 for final distribution to the red, green and blue CRTs. The ADboard is mounted to the A board and contains the digital convergence circuitry, along with a RGB output toIC3006 to display convergence data, auto-registration flags for the sensors during Flash FocusTM, and internalcrosshatch and dot patterns.

Although this chassis is currently a board level repair unit, the distribution of the video signals among three mainboards requires diagnostic procedures to determine which board to replace. If the boards become unavailablein the future and component level troubleshooting becomes necessary, the diagnostic methods covered in thischapter will become more valuable.Video failures fall into three main categories:

1. No video

2. Distorted video

3. Improper level

Although the video signals are routed through many different paths depending on the type of signal being received,these different pathways can be used to an advantage when diagnosing video failures. The picture & picture(Twin Picture) feature provided by the MIDTM circuitry provides a useful diagnostic tool. Since it is able to displaytwo video signals simultaneously, isolating which stage is causing the problem can be accomplished easily. Thisfeature will be used extensively in the troubleshooting procedures to follow.

85


CBBD.

7/17/0220.1TVP14

ANALOGTUNERS

IC002SW.

Q9, Q11, Q13MIXER

IC7806,IC7807DRC

PROCESS

IC8801OSD

IC001MAIN MICRO

IC7205, IC7603DTV TUNER

AND PROCESS

IC205MAIN SW.

IC8601IC8703, IC8902MID PROCESS

IC201,IC202,IC204,IC207

ANALOG VIDEOPROCESSING

IC401A/VSW.

IC200COMPONENTINTERFACE I/FIC201 SUB SW.

NTSCORHD

INPUTCN4001/CN003

NTSCSUB

PATH

MAIN SIGNAL PATHNTSC INPUT/ PIP

NTSCMAINPATH

NTSC

OSDOSDMAIN

CN002/CN3022

CN8601/CN005

OSD

CN8801

CN001/CN3020

VIDEO5,6

VIDEO 1,3,4

CN008/CN1200

HD(33.75kHz)

VD (60Hz)

HB BD.

QM BD.

B BD.

U BD.

C BD.

A BD.

VIDEO 2

SUB

MAIN

A1-3 A5-7

C11

13

C15

17

HDVIDEO

5,6*

*SERVICE MODEENABLED PATH

A3-5 A7-9

B6

B9

1, 3, 5A9

MN-SB-SW.

CGBD.

CRBD.

IC3006VIDEO

PROCESS

ADBD.

1,2,3

20

DREG

YS

RGB

CN3012/CN1601

CN3013/CN1602

CN3011

CRT B

CRT G

CRT R

FIGURE 20-1 - VIDEO BLOCK - RA-5A CHASSIS

Troubleshooting a No Video ConditionTwo possible causes of this symptom must be ruled out first. There must be high voltage present and the unithas not encountered an AKB error. Listen for the sound of high voltage and verify it is remaining on by observingthat the CRT filaments are still glowing. This chassis does not indicate high voltage problems in the diagnosticsfeature. If the high voltage is not present, refer to Chapter 19 for troubleshooting methods. AKB errors will bedisplayed by the timer LED flashing in sequences of five. AKB troubleshooting will be covered in Chapter 27.

Once high voltage and AKB have been ruled out, try bringing up the customer menu. If it appears, there is agood chance the video process IC3006 is working properly. If it does not appear, try entering the service mode.The OSD for this mode comes from the main CPU IC001 on the B board. The appearance of the service dataalso confirms the video process IC is likely OK and that there is a high probability the failure is on the Q board.The purpose of trying to get OSD on the screen is to eliminate IC3006 as a source of the failure. It could still beat fault since active video enters it via a different input.

Using the internal DTV tuner is valuable for isolating video problems. It has a direct path to the video processorfor HD signals and non-HD signals follow a direct path to the DRCTM. A lack of video from the HD tuner along withno video from any of the external inputs or analog tuners points to a defective Q board. If DTV signals can bereceived but not external sources, the next test can be performed.

The picture & picture feature will be used next. It is advisable to use the analog tuners when performing this test.One item that is unique to this new feature design is that HDTV signals from the DTV tuner HD sources input tovideo 5 and 6 sources can only be displayed in the left box. NTSC inputs and the two analog tuners will displayin either box. By using this feature, the main and sub-video paths are displayed together and a wealth ofinformation can be obtained to isolate the video failure.

86


Video Appears in Right Box Only: The sub-video path is working correctly. An interruption in the main videoprocessing has occurred. The problem is likely to be on the B board since most of the processing occurs there.The Q Box routes the main and sub-video into the MIDTM circuits for side-by-side display. The problem could beon the Q board. Isolate the two by checking for video signals at CN005 pins A5, A6 and A7. If no video ispresent, repair or change the B board.

NOTE: This circuit has an interesting feature that allows the user to enlarge the left or right box with the remotejoystick. When both inputs are non-HD signals, the larger box will automatically switch in the main video source.By default, the two boxes appear equal in size with the main source on the left. If the right box appears largerthan the left, the main video signal is being sent there.

Video Appears in Both Boxes: The main and sub paths are functioning. This is the only time in which NTSCresolution video is not sent to the DRCTM circuits for line doubling. The twin view signal is routed to the videoprocessor IC3006. The DRCTM is either not receiving main video, not processing it, or the line-doubled video isnot being switched properly. All of these suspected areas are located on the Q board and must be replaced asa unit.

No Video in Either Box: If the boxes appear over a gray background, the MIDTM circuits and the path to the videoprocessor is OK. The lack of video indicates a failure of both the main and sub-video paths. Since all decodingand video switching of the main and sub paths occur on the B board, this is where the problem lies.

Video Level or Distortion: The same procedures used to isolate a no video condition can be used to locate thesource of distortion or level problems. With the introduction of multiple A/D and D/A converters and digitalprocessing circuits, noise in the video is likely to be more common and can take on some strange symptoms.Fortunately, most digital noise problems have a distinct digital appearance. They may be stationary on thescreen or move around in a clock-like stepping motion. Minor or severe loss of picture detail is caused by one ormore of the parallel bit lines being inactive. The more significant the bit, the more detail loss will occur. Powersupply and external noise will “float” since they are not synchronized with the video.

Using Component Video: The use of a component video source is useful when the need arises to troubleshootbeyond board level to a specific component. It bypasses all of the decoding circuits, thus, eliminating severalpotential sources. A high definition component source is better. The DRCTM is also bypassed as a potentialcause. A unique feature in this chassis is the “HD Bypass” control. IC002 on the B board normally switchesvideo from the Q Box into the video processor IC3006. By entering the service mode and selecting category“OP” and item “HDPT”, the data can be set from 0 to 1. This will cause IC002 to switch a 1080i source only fromvideo 5 or 6 input directly to IC3006. It is a useful tool in isolating the Q Box as a potential problem source.

87

1. Features

Chapter 21 - Troubleshooting the RA-6 Chassis

OverviewThe RA-6 chassis is found in the KP51HW40 and KP57HW40 models. It provides an affordable “high definitionready” set with a 16:9 aspect ratio. It is also found in the KP43HT20, KP53/61HS20 and KP53/61HS30 as a“High Scan” 4:3 model. Much of the circuitry is the same as in the RA-5A chassis, especially the deflection andhigh voltage section. It does not incorporate a built-in DTV tuner but is able to accept two sources of HD videofrom external devices using component video. It will not accept RGB or VGA sources. The power supplycontains far less components than previous models and is easier to troubleshoot. New circuit designs andscreen composition provide a sharper picture compared to previous models to take advantage of the high definitiondisplay capabilities.

The Flash FocusTM circuits incorporate a new feature that allows the copying of registration data from the normalpicture mode to the wide zoom, zoom and 1080i display to minimize convergence time. Details and troubleshootingof the convergence circuits will be discussed in Chapter 28.

88

22. RA-6 Power Supply Troubleshooting

Chapter 22 - RA-6 Power Supply Troubleshooting

General DescriptionThe power generation and distribution has been simplified by utilizing a traditional analog standby supply providingunregulated B+ for the main AC relay and regulated 5V for the main CPU, NVM and IR receiver (not shown).More detail on this circuit will be covered later in the shutdown troubleshooting section.

As shown in Figure 22-1, the main power supply consists of a single oscillator circuit (IC6003) with FET driversand a single PIT, or Power Input Transformer. Once the unit is powered up and the main relay RY6002 is closed,current flows through R6002 to minimize the initial surge. RY6003 closes as soon as 11V is generated by thesecondary. If this relay does not close within two seconds, the oscillator will stop since PH6002 monitors thisrelay. This will be covered in Chapter 23.

Starting:

Approximately 300VDC will be supplied to Q6006 and pin 18 of IC6003 to start the oscillator. Pin 1 will monitorthe unregulated B+ for excessive or low voltage. IC6003 will begin oscillating and sending square wave signalsout of pins 12 and 16. These drive signals will always be 180° out of phase and at a 50% duty cycle. The IC doesnot require feedback from the T6001 to operate. This makes it simpler to troubleshoot since the oscillator canrun on its own as long as start and correct sense voltage is present. Once the supply is running, it will supply itsown stable power source known as VC1 and input it at pin 8.

When pin 16 of IC6003 is high, Q6006 will turn on. 300VDC will be output at the source to C6047 and it willcharge. Current flows through the primary of the PIT entering pin 1 and exiting pin 2. R6076 and R6080 providethe ground return for the current. Q6005 is off at this time since pin 12 is low. Once pins 12 and 16 reversepolarity, Q6006 will turn off and Q6005 turns on. A short circuit is placed across the primary windings and C6047to discharge the capacitor for the next cycle when Q6006 turns on again.

Regulation:

Voltage regulation is maintained via a feedback path to monitor the 135V line for stability. IC501 and photooptical isolator PH6001 sends this feedback information to pin 2 of IC6003 to vary the oscillator frequency.Current monitoring enters pin 9 by looking for a voltage drop across R6070 and R6076. The voltage drop atthese resistors is zero to .2VDC. Any higher voltage level will cause the oscillator inside IC6003 to increase infrequency to reduce voltage output.

Soft Start:

Soft start is accomplished by keeping the oscillator at high frequency for about three seconds at startup. This isinitiated by the charging of C6021 on pin 6 of IC 6003. The initial AC current is reduced by 50% during this time.This, combined with the durability of the FET drivers, allows the supply to start and let the unit go into protectmode, preventing damage to Q6005 and Q6006.

89


3

4

IC6003

1

6

18

SENSE

VD16

12

15

11

9

8

2

1

3

4

7

9

8

12

10

11

15

13

14

18

16

17 +6V REG

-5V REG

4

3 2

1

2

IC501CONTROL

DM-584 1

5

TIMER

OCP

VC1

FB

R6003

RY6003

AC LAC H RY6002

PH6002

R6002

C6021

+

D6004

D6007

R60640.1 1/2W

Q6006

Q6005

R6080

R6076

D6011

11V

PH6001

R6037

R6038R6040

R6050

R50120.22 2W

R5032

D6003AU

+19V

AU-19V

AU GND

D6030

D6011 D6081

R6036

R6008

D6003

C6003

D6009D6005

C6047

D5010

R50070.47 IC5003

IC5004D5006

D5008D5009

T6001

D5002

D5005

D5004

CN5004PIN 9

TOIC5002OVP

PS5003

PS5004

PS5005

PS5006

PS5002 5APS5001 5A

-5V

+6V

+11V

+15V

+22V

-22V135V

-15V

TOIC5002OCP

FIGURE 22-1 - MAIN POWER SUPPLY RA-6 CHASSIS

1

2

D6002

22.1TVP14 1470 7/11/02

+

TroubleshootingA failure in the main supply can occur due to several reasons. Below are some possible scenarios:

1. The oscillator and/or drive circuits will not operate.

2. Component failure due to excessive current or line transients.

3. Regulation problems.

4. The unit goes into protect mode. This will be covered in Chapter 23.

If the supply is not running, it is important to check and see if Q6006 and/or Q6005 have shorted. R6064 willusually be open in this case. If they are not shorted, it is necessary to determine if the supply starts up and thenstops. This can occur without tripping the main relay for protection.

90


Dead Supply. Switching Transistors Shorted: A more cautious approach must be taken when this happens.There is slight possibility that excessive current or a higher possibility that line transients caused them to fail andthe loss of a newly installed set is not only frustrating, but costly in parts and wasted time. Static resistancereadings of the secondary lines to ground are the first order of business. This supply has ± supply rails so do notforget to read across them for low resistance readings. A quick visual check for overheated components is alsoa good idea. Check for open fuse links on the secondary lines, as these are valuable clues. If the above itemscheck OK, the supply can now be started.

The old method of jumping the main relay and bringing up the AC voltage with a variac will not work in this powersupply design. Even with the main relay jumped and an external DC source applied to the V Sense line, theoscillator will not start until at least 70VAC is reached. At the 70VAC level, the oscillator will start and stop at one-second intervals. The horizontal and vertical deflection circuits will start and stop. The rise and collapse of thedeflection will burn the phosphors in the tubes if they are lit. Do not attempt to run the supply at lessthan 80VAC.As mentioned earlier, this power supply design is extremely durable and can survive a startup with a direct shorton any of the secondary lines. As long as measurements are made for static shorts on the secondary lines, thesupply can be started at full AC. It will stop oscillating on its own or the unit will go into protect mode if a problemstill exists. AC current draw will still need to be monitored at turn-on to provide an indication of what step to takeif there is still a problem. Normal AC current draw for this chassis is between 1.3A and 1.8A, depending on ACline voltage and picture brightness. With 120VAC and color bars in the Vivid Mode, the unit draws 800ma.

Current Rises Rapidly and Unit Shuts Down: Normal current draw is 400ma at turn-on with a rise toapproximately 800ma occurring three seconds later. This is due to the internal soft start circuit of IC6003.An initial current surge of 2A or more indicates an over-current condition. Begin removing secondarysupply sources. This can be done by lifting diodes or fuse links. Start with the 135V line since this is thelikely source. Do not lift the diodes for the 135V. This will open the regulation loop and cause the supplyto output maximum power. Disconnect at CN504. If the over-current condition still exists, the problemlies in T6001 or the driver circuits. Check the waveform at the output of Q6006 for symmetry. A defectiveT601 will cause ringing distortion. If the waveform is not 50% duty cycle, IC6003 may be defective andcausing the driver transistors to overlap.

Little Or No Current Draw: This is likely to happen if the switching transistors failed due to line transients.The high impedance FET gates are protected by 10 diodes (not shown) and seven are zener diodes.Lifting of the diodes and checking each for shorts or leakage is going to be necessary. Compare drivepulse shapes (if any) at both gates to be sure they are clean and of the same level. It is possible thatmost or all of these diodes are defective. No drive pulses from pin 12 or 16 may indicate IC6003 wasdamaged by the transient. Verify the start voltage is present at pin 18 (300~340VDC) and the V SENSEline is at least 1.7VDC and less than 2.5VDC. The unit may be going into protect so watch closely fordiagnostic flashes of the timer LED.

Dead Supply. Switching Transistors Not Shorted: This is a condition that is most likely to be encountered if thesupply was not damaged by large transients. The important steps to take in this situation are to monitor ACcurrent and listen for relay clicks. This will verify whether the supply is not starting. The normal sequence ofevents at turn-on is as follows:

1. The main relay RY6002 engages. The click of this relay verifies the standby supply is operating.

2. Inrush current relay RY6003 engages next. The VC1 voltage from D5006 of the main supply is applieddirectly to this relay. The time-period from RY6002 engagement to RY6003 engagement is less than500ms. It is very important to listen for this rapid event. It will verify whether the main supply hasattempted to start. If only a single click is heard, the main supply is not starting or RY6003 is not engaging.There will be a second click at least one second later as this unit will go into shutdown if the main supplyor RY6003 is not operating.

91


3. If a problem exists that warrants protection, a third relay click will be heard. This is actually RY6002 andRY6003 releasing simultaneously and will occur from one to several seconds later. Refer to Chapter 23for troubleshooting the protect circuits.

Assuming two rapid clicks are not occurring and little or no AC current is being drawn, the main supply must nowbe checked. Place a jumper across RY6002. This will provide start and sense voltages to IC6003. Unplug theC boards from the tubes while performing this. Verify 340VDC at Q6006-D. If it is missing, R6064 has openedor the unregulated B+ line is faulty. If unregulated B+ is present, check pin 18 of IC6003 for start voltage. At120VAC input, the normal voltage at this pin is approximately 340VDC. Check for 2.8VDC at V Sense pin 1.Verify zero volts at OCP pin 9. If any DC is read, R6086 and R6080 have opened. The oscillator inside IC6003will run if both voltages are correct and OCP is zero. Check for drive pulses at pins 12 and 16 of IC6003. If noneare present, IC6003 is probably defective. If they are present at the output pins but not at the FET gates, one ormore of the protection diodes are leaking or shorted. The gates of Q6005 and Q6006 may be shorted but this israre.B+ Regulation Problems: The regulation loop is relatively easy to troubleshoot. IC501 monitors the 135V line viaR5032. Any rise in the voltage at pin 1 of IC501 will cause the output at pin 4 to go lower. The resulting pull-downat PH6001 pin 2 causes the LED to increase in brightness. Pin 4 of PH6001 will pull down the voltage at pin 2(FB) of IC6003 and the oscillator frequency will rise to reduce the output voltages at the secondary lines. Theopposite chain of events will occur if the 135V line should drop in voltage. The use of variable DC voltages in theregulation loop allows for simple troubleshooting methods.

Excessive B+: The unit will shut down and the timer LED will blink in sequences of three. The idealmethod of troubleshooting is to isolate entire sections of a circuit at one time. Monitor the 135V line witha DVM while testing this circuit to verify a legitimate regulation problem. If the 135V line is not goingabove 139V, the OVP circuit is malfunctioning. This will be covered in Chapter 23. By shorting pin 4 ofIC501 to ground, the result on a normally functioning supply would be a significant drop in secondaryvoltages. If the unit still goes into protect with pin 4 of IC501 shorted, the failure has been isolated toPH6001 and its associated components or even IC6003 itself. If the unit stops going into protect, thefailure lies between IC501 and the sample taken from the 135V line. IC501 is known to be extremelyreliable and an increase in value of R5032 is likely.

Low B+: Read the voltage across PH6001 pins 1 and 2. Zero volts present indicates IC501 is reacting tothe low B+ correctly and turning off the LED. Measure the DC voltage at pin 2 of IC6003. If it is lower than2VDC, PH6001 is the cause. If more than 2V is present, check pin 6 of IC6003. The capacitor to ground(C6021) controls the soft start duration at turn-on by charging. If C6021 shorts or has leakage, theoscillator will remain in high frequency and generate low output voltages.

92

23. RA-6 Protect Circuit Troubleshooting

Chapter 23 - RA-6 Protect Circuit TroubleshootingGeneral Description

As illustrated in Figure 23-1, several circuits are monitored for protection. Some lines are monitored by the self-diagnostics feature while others are not. The self-diagnostics feature can assist in isolating a particular circuit.Below is an example of the diagnostics page which is entered by pressing “DISPLAY”, “5”, “VOL –”, and “POWER”:

Self Check:

2: +B OCP 00

3: +B OVP 00

4: V Stop 00

5: AKB 00

6: Low B 00

7. H STOP 00

8. HV 00

9. AUDIO 00

101: WDT 00

The numbers on the left indicate how many times the timer LED flashed, which designates the probable cause ofthe shutdown. The flashes on the LED will occur at one second intervals, followed by a three second separationperiod and repeat again. The numbers at the extreme right indicate how many times the problem occurred up to99 events. You can see why this is beneficial for intermittent troubleshooting. It is always a good idea to clear theevents before exiting and that can be done by pressing “8” “enter” on the remote. This is not the same aspressing these buttons in the service mode. It will only clear the events and not reset customer defaults. Bewarethat the service manual instructs you to enter the service mode to clear these and that is a mistake. You can doit right from this screen.

+B OCP: Excessive current on the 135V line. This is usually caused by flyback problems or secondary loads onthe line. The circuit could also be tripping for no reason. This is why you should always monitor AC current whilethe unit is shutting down. It will help to know if you are really dealing with an over-current condition and a morecautious approach can be taken while troubleshooting.

+B OVP: The 135V line has exceeded 139 volts. Refer to Chapter 22 on troubleshooting regulator problems.

V Stop: The vertical deflection circuit has stopped operating. Loads on the I2C data and clock bus can also bethe source of this problem.


Low B: The 5V source from the main power supply is monitored for low voltage by Q714 on the A board.Problems on the +/- 15V, +/- 19V and the +/- 22V lines can also generate a diagnostic indication here.

H Stop: Horizontal deflection has failed. Since the unit has a separate high voltage circuit, the set will shut downto protect the CRTs. This will be covered in Chapter 23.

HV: High voltage has exceeded specified limits or there is excessive current in the flyback transformer.

93


28

31

43

44

45

43

72

24

IC309Y/C

JUNGLE

26

25

Q5003,Q5004LATCH

IC704MAIN uCOM

MAINRELAY

D5014D5007

AUDIOPROTECT

STBYUNREG

7.5V

RY6002

Q5001

Q5002

Q5005

D5001OVP D5022

Q714

SCLK

SDAT

H PROTECT

V PROTECT

IK5V LP

135V OCP

135V OVP

+15V LP

+22V LP

6V OVP

HV PROTECTD BOARD

-19V LVP

+19V LVP

FIGURE 23-1 - PROTECT CIRCUITS RA-6 CHASSIS 23.1TVP14 1472 6/12/02

34

25

58

AUDIO: DC voltage has been detected on the speaker lines. This is usually caused by audio output IC708. Theaudio circuits are located on the A board.


The above protection circuits have dedicated communications, directly or indirectly, with the main micro controller,IC704, located on the A board. The 135V OCP/OVP, Low B, H Stop, HV and AUDIO lines have direct connections.V Stop and AKB notify IC709 by way of the video process IC309, which announces the event via the data busline. The remaining protect circuits have no communication ties with the main CPU IC709, but will also generatesix blinks of the timer LED. They are:

1. Audio -19V LVP monitored by D5026

2. -15V LVP monitored by D5023

3. +15V, AU +19V, and +22V LVP monitored by Q5007 and D5083

4. Reg 6V OVP monitored by D5019

5. Standby unregulated B+ monitored by D5001

6. Unregulated B+ for low or excessive level monitored by V Sense at pin 1 of IC6003.

94


Shutdown – No Diagnostics IndicationThe first step necessary is to listen for the sequence of relay clicks when the unit is powered up. If two clicks areheard less than 500ms apart followed by a third click at least one second later, the protect circuit is activating.The initial rapid clicks indicate the main supply is powering up and the inrush relay RY6003 is activating. If onlyone click is heard, AC current must be monitored to determine whether the power supply is starting or RY6003 isdefective. If current above 500ma appears, the supply is starting and the unit is shutting down because RY6003is not engaging. Troubleshoot RY6003, PH6002 and its associated components. If no current is read, the powersupply is not starting; refer to Chapter 22.

The next circuit to check before moving on to the voltage protection lines is the V Sense at pin 1 of IC6003. ADVM with peak-hold is recommended. The DC voltage must be more than 1.8V and less than 5V. Any deviationfrom this indicates resistance value changes in the voltage divider network or a loading of the line by protectdiode D6009. Once the inrush relay and V Sense circuits are eliminated, locating the protection line causing theshutdown is necessary.

NOTE: Beware that a V Sense anomaly can cause the self-diagnostics to flash the LED in sequences of six,indicating a loss of 5V which is monitored by Q714 on the A board. This is a quirk in the diagnostics circuit. Eventhough the LED is flashing six times, the event is not stored in the diagnostics failure history. Over-currentconditions on the ± 15V lines have also generated six flashes.

All of the low B+ voltages on the secondary of T6001 are monitored for the loss of these voltages. There is nocurrent protection. Only the 135V line is monitored for over-current and this is displayed in the diagnosticsfeature. Even though an over-current condition may have been the original cause, these lines are protected withfuse links. One or more of the fuses may be open causing the shutdown. Checking the fuses with an ohm/meteris the preferred initial step. If a fuse link is found open, troubleshoot that line for a possible loading problem. Theonly line that is monitored for over-voltage is the regulated 6V from IC5004 by zener diode D5018.

Shutdown – Diagnostic Indication2X Flashes: Verify a legitimate over-current condition by monitoring AC current at shutdown. If high, disable HVcircuit first, followed by horizontal deflection circuit. Refer to Chapter 24 for troubleshooting. If the AC currentdoes not exceed 2 amps at turn on, IC5002 is firing. Check the IC and possible R5102 open.

3X Flashes: Monitor the 135V line with a peak-hold meter. If the voltage peaks above 139V, refer to Chapter 22for troubleshooting regulator problems.

4X Flashes: Check the DC voltage at the clock and data lines at main CPU IC001. The voltage should be4.6VDC. If either is low, locate the component loading the line. If OK, troubleshoot the vertical circuits.

6X Flashes: The 5V source is monitored for loss by Q714 on the A board. IC12 on the A board regulates the 6Vfrom the power supply. Verify the presence of 6V entering the A board at CN4-3 and 5V exiting IC12.

7X Flashes: Troubleshoot horizontal deflection circuit covered in Chapter 24. Disconnect the C boards fromthe tubes while working on this circuit.

8X Flashes: High voltage has exceeded specified limits or there is excessive current in the flyback transformer.Refer to Chapter 25.

9X Flashes: The audio output IC has shorted or the protect components on the A board have failed

95


STBYTRANS.

5VREG

R5016

R5026

IC5006

D5001

5

67

2

31

R5038

D5020

R5020Q5002

D5007

CN6-5CN6-4

TO 135VOVP

IC5002-5

SELF DIAGNOSTICS

D5022

RY6002

D5017

C50509.8V

R5011

IC5005

IC5002

C5051

Q5005

R5010

R5013

5V AU+19V

+ AU-19V

-15V

+15V

AU+19V

+22V

IC50046V

135V

D5019

D5023

D5033

D5026

D5024

R5043

D5025

R5046

D5032

D5031

Q5007

6V

D5014

R5012

T6001PIN 11

ABL

Q5004Q5003

D5015

R5021

RELAYHIGH

R5028

Q5001

+-

-+

D5018 6V OVP

23V

+

FIGURE 23-2 - PROTECT CIRCUITS RA-6 CHASSIS 23.2TVP14 1471 7/11/02

96

24. RA-6 Deflection Circuit Troubleshooting

Chapter 24 - RA-6 Deflection Circuit TroubleshootingThe deflection circuits in the RA-6 chassis are identical to the RA-5A chassis in that horizontal sweep and HV aregenerated in separate circuits.

Horizontal Deflection TroubleshootingReferring to Figure 24-1, horizontal sweep is generated in the conventional way using an H drive signal from pin40 of IC309 on the A board. It is amplified and transformer coupled to the horizontal output transistor Q8024.The deflection yokes and T8003 are driven. T8003 generates 200VDC for the dynamic focus correction circuitand a ± 100V source to provide offset of the red and blue deflection yokes for centering to the green CRT.Horizontal centering control is also provided by IC8012 and Q8039.

IC8005 is a PWM control device that serves to modulate the horizontal output B+ level to T8003 for pincushioncorrection. The H pulse at pin 14 provides the timing for the sawtooth reference while the E – W signal suppliesthe necessary vertical parabola signal for scan width modulation.

Q8031 and Q8101 buffers and shapes the H pulse for use in OSD timing and, more importantly, tells the Hprotect circuit that horizontal sweep is occurring.

Since there is no flyback transformer incorporated into this circuit, current demands on the horizontal outputtransistor are lower and damage from CRT and flyback arcs are nonexistent. This also makes troubleshootingeasier. Loss of horizontal deflection is likely to occur because of Q8024 failing. It is wise to check Q8027 whenthis happens since it is easily damaged from the large current surge when Q8024 shorts and it also may havebeen the reason for the failure. Powering up this circuit at low B+ levels using a variac is not possible. The mainpower supply will not operate at AC input levels below 70V. This is sufficient input to produce full secondaryvoltages and the new transistor could fail if other problems are still present. There is, however, a way to utilizethe soft start feature of the power supply to get an initial idea of the status of this circuit.

Place an oscilloscope probe near Q8027 and set the gain to 500mv. Set sweep for horizontal frequency viewing.Apply 120VAC to the set while watching the scope. The soft start in the main supply will keep initial current atapproximately 50% of normal level for about three seconds. In this chassis, initial AC current will start at 700maand rise to 1.5A. If the horizontal stage has a problem such as a defective T8003 or deflection yoke, the initialcurrent will begin a much higher levels and the unit will go into protect. If this is happening, try to view the signalat Q8027 during this period for the presence of pulses. If the transformer or a yoke is defective and caused theoriginal failure, a distorted (if any) waveform will appear. If clean H pulses appear before the shutdown, suspectexcessive loads on T8003 or a problem with the horizontal regulator IC8005 and Q8027. Note: A common causeof secondary loads on T8003 is CRT drivers that have shorted and loading the 200V line.

Pincushion TroubleshootingThe simplicity of the pin correction circuitry in this chassis should provide for easy troubleshooting. The keysymptom to observe is whether the picture is stretched or of insufficient width with pincushion distortion.

Picture Too Wide: Q8027 is not modulating the scan width accordingly and is either shorted or in saturation.There should be approximately a 15V difference between the source and the drain. Shorting the gate of Q8027will aid in determining whether IC8005 is overdriving it or the transistor is at fault. If the picture width is substantiallyreduced, check IC8005 for missing H pulse at pin 14 before replacing.

Insufficient Width: Q8027 is not receiving pin correction signals. Check for a parabolic signal at the gate. If notpresent, verify the E –W signal is at pin 6. If it is, check the associated components around IC8005 beforereplacing it. Pay close attention to the components supplying feedback to the operational amplifiers in this IC.Beware that the NVM IC storing the pincushion correction data has caused problems in some previous models.

97


IC8005H DRIVE

CTL

2

3

6

14

T8003HOT

1

4

3

21

H OUT

H RET

1

42

1

3

5

H OUT

H RET

1

4

H OUT

H RET

1

4

T8002HDT

Q8020

Q8016

Q8004

Q8030

Q8023 Q8024H OUT

Q8031

Q8101

H PULSETO A BOARD

Q8039

IC8012

IC8019HLC

C8137

D8032

D8045

DYB

DYR

DYG

H CENT.

+-

+-

Q8027

135V

200V TODF CIRCUITS

E-WIC309PIN 47

A BOARD

12V D8033

H DRIVEIC309PIN 40

A BOARD

IC8009

112VDC

+

FIGURE 24-1 - HORIZONTAL DEFLECTION RA-6 CHASSIS 24.1TVP14 7/17/02

Vertical Deflection TroubleshootingNo Vertical Deflection: The first instinct of the technician is to go after the vertical output IC8003 and understandablyso. It is a drive component with heavy current usage and heat dissipation, and it is usually the cause of thefailure..

The first check that you should perform (and this applies to all Sony televisions of the last seven years) is tocheck the voltage level of the clock and data lines on the I2C bus. They are conveniently labeled SCLK and SDAT(sometimes SCL and SDA). The DC voltage should not be lower than 4.6 volts. If either of these lines is loadeddown, the vertical oscillator will not start. This is the number one cause of multiple component replacements fora simple vertical problem. You should always check the clock and data level whenever you have a strangeproblem and, particularly, if it appears that you more than one problem. Although most television chassis will notproduce vertical deflection, some will generate other symptoms. As an example: The AA-2W used in Sony’sKV32/36XBR200 sets will display a magenta colored raster with no video and insufficient vertical height. Assumingthe bus is okay, move onto the next step.

Since this chassis will go into protect mode and shut the unit down, certain measurements must be taken andwatched for during the time the unit powers up and shuts down. Unlike previous designs, the V stop featurecannot be overridden since pin 35 of IC309 is looking for vertical pulses from Q8001. Always remove the Cboards from the tubes when servicing a no vertical sweep condition.

The ± 15V lines are the first to check. If OK, place a scope probe and watch for a moment of vertical sawtoothsignal at pin 1 or 7 of IC8003. Any presence of drive signal here indicates IC309 is generating V drive andisolates the problem to the output circuits. Verify vertical ramp signal on the high side of R8036 or R8039 in thereturn circuit. The circuit could be running and Q8001 is not sending the V signal to IC3006.

98


V DEF

V RET

V DEF

V RET

V DEF

V RET

-15V

+15V

R8047

L8003

D8004C8015

CN8006-3VDRV+

CN8006-5VDRV-

R8147

R8041

R8032

R8018

R8014

R8013

+15V

C8001

R8019

R8015D8001

R8022

Q8001

C8017

CN8007

CN8008

CN8009

CN8006-7VP

DYR

DYG

DYB

R8022

R8071 R8036

R8039

TH8001

+

1 2 3 4 5 6 7

+-

IC8003LA78045

FIGURE 24-2 - VERTICAL DEFLECTION RA-6 CHASSIS 24.2TVP14 1473 6/13/02

123

123

123

Repeat Vertical Output IC Failure: If IC1509 fails immediately upon replacement or in a short amount of time, itis usually the fault of C8015. This is the boost capacitor. It charges to almost 30VDC during the lower half of thevertical sweep to provide additional voltage to allow the beam to retrace to the top rapidly. When this filter driesout or opens, the output IC will attempt to accomplish the retrace but the negative feedback line will resist thesudden voltage kickback from the yoke and the +15V drive will cause the IC to draw excessive current. Insmaller televisions, a boost capacitor failure causes slight loss of vertical at the top with some fold-over.

Insufficient Vertical Height: Either the vertical output IC is being told what height to display or it has a problem andis unable to comply. Due to the nature of the operational amp within IC5004, it is rare for it to be the cause.Operational amps have massive amounts of gain, which is why they need negative feedback to keep them undercontrol. Gain problems are most likely to be caused by improper supply voltage (very rare) or problems in thefeedback line. This is why you should always scope the feedback line when height or linearity problems arise. Inthis chassis, the best point is the top end of the ground return resistors (R8036 or R8039). What should normallybe here is approximately 1VPP of vertical rate sawtooth. If there is a problem, you will observe one of two things:A significantly larger sawtooth level or horizontal frequency contamination in the sawtooth. A large sawtoothindicates one or more of the ground return resistors or the thermal compensator TH8001 has opened. Thenegative feedback of the op amp will respond by reducing gain. If there is a large amount of horizontal componentin the feedback, the amp will also reduce gain since the average DC level will be higher at this frequency. Thevertical deflection yoke windings are right next to the horizontal windings so it is very easy to induce this into thevertical return. Suspect an open C8001 or C8017 at this point.

Should the feedback line check OK, you now have a possible input problem. IC3006 can cause this and it isdifficult to verify without replacing it. Beware that faulty NVM ICs have been known to cause vertical heightproblems.

99

25. RA-6 High Voltage Circuit Troubleshooting

Chapter 25 - RA-6 High Voltage Circuit Troubleshooting

FIGURE 25-1 - HIGH VOLTAGE STAGE - RA-6 CHASSIS

T8005FBT

IC8007PROT. 1

Q8028-9ABL

DRIVERQ8004Q8016Q8019Q8020

H DRIVEQ8023

H OUTREG.Q8027

DRIVERQ8036Q8037

IC8008PWM GEN.

1

10

3

3

C8118 LOTT8004

1

14

12

12

1

62

2 41

HV BLK

7VIDEOOUT B+C B BD.

14

10

10

9

IC3006VIDEO

PROCESS40

7

3

5

IC8006PROT. 2

5

3

2

D8025

D8023

+12V

CN8016

CRTHV

R8171100

+135V

D803615V

MIX OUT TOIC8007

Q8035HV REG.

PCH

CN6106/CN8013

CN8004/CN3005

CN3007/CN8006

V BD.VEL MOD COILS

CN3023/CN9001

CN3010/CN9001

CN3001/CN9001

+135VSEC.P.SIC6001(G BD.)

D8039200V

R8219

D8038

R8223

CN8022/CN7304

D8029D8030

C8142

ABL

RR8153 PROT.VR8002

100kD8017

N

D803118V

D8034

D8035R8160

R819810k

Q8021

Q8022

DRIVERSQ8005,Q8032

+15V CN8021

A BD.

G BD.

D BD.

Q8038HV OUT

D BD.

+135V

+135V

111

200V TO

R8196

8.1V

7.46VDC

7

11

S

D

G

D8015LATCH

18

6

VR80015kHV

1

1

7/17/0225.1TVP12

General DescriptionFigure 25-1 illustrates a block diagram in order to provide an overall view of the circuitry on the D board forgenerating high voltage. The main components consist of a regulator stage to vary the B+ level to the flybacktransformer for HV level control, a driver and output stage to switch the flyback on and off, a flyback transformerto generate HV and a LOT transformer to generate heater voltage and 200VDC for CRT cathode bias.IC8008 is a PWM generator and driver to control the on and off time of HV regulator Q8035. The sawtoothwaveform for the PWM generator is synchronized to the horizontal drive pulse at pin 14 to provide a stablereference. A sample of HV level is taken from the HV block assembly and enters pin 12 to provide an error loopby which to vary the duty cycle of the drive pulses to Q8035. Q8038 provides the necessary switching to turnT8004 and T8005 on and off and maintain a HV level of 31KV.

HV level and current are monitored by IC8006 and IC8007. They will stop high voltage generation to provideprotection for the HV components, CRTs and X radiation level. This is accomplished by disabling the H drivepulse from video process IC3006. Both the HV level and shutdown threshold are shown as adjustable byVR8001 and VR8002 but these controls are sealed with epoxy at the factory and are not adjustable.

100


TroubleshootingHigh voltage circuit failures generally fall into four categories: No HV, low HV, excessive HV and excessivecurrent. The latter two will cause the HV circuit to cease operating and a high will be sent to IC704 on the A boardto place the unit into protect-mode. The timer LED will flash in sequences of eight.

Dead HV Circuit: The initial concern with this symptom is whether the HV output Q8038 has shorted. This will beevident by the fuse link being open on the 135V line. If Q8038 is not shorted, it is important to be certain the highvoltage did not come on and shut off suddenly by observing the timer LED for a diagnostic indication. Once it isconfirmed the HV is not starting, a dead HV circuit will be caused by a shorted HV output transistor Q8038 or amalfunctioning circuit. The approach for either reason will be different.

No HV – Q8038 Shorted: Verify Q8035 is also not shorted. It may have failed after the fact or could bethe reason for Q8038 shorting. The extremely functional soft start circuit in the power supply will provideenough current limitation to prevent a repeat failure of Q8038 in most cases. If the HV regulator ismalfunctioning or there is excessive current draw, the HV or 135V protect circuits will activate during thesoft start period. If the unit shuts down after replacing shorted components, the HV circuit will need to bemonitored to locate the cause. Place your scope probe somewhere near the HV output transistor orflyback. Most scope probes are not able to handle the direct spike level from the flyback so this is a safemethod. Connect a DVM to CN8016 and monitor the DC voltage. It must not rise above 7.5VDC, whichwould signal a HV regulator problem. Apply AC power with the variac and watch for the pulse ( if itappears). If the flyback is defective, one of two waveforms is likely to appear and you are going to haveto attempt to observe them during the startup and shutdown duration. The first may look like a sinusoidalwaveform with a distinct ringing appearance. This definitely indicates flyback problems. The secondphenomenon will be a retrace pulse with a second, lower level, “phantom” pulse, which also indicates adefective flyback. If the retrace pulse looks great but starts to jitter and dance on the scope screen, thisusually indicates excessive loading of secondary lines. In this unit, it can be loads on T8004. Measurefor shorts on the filament and 200V line. The flyback transformer T8003 only has two load circuits andthey are the HV and focus blocks.

Do not worry about excessive high voltage problems. If the high voltage rises too high, the horizontaldrive pulse will be cut off, the circuit will stop functioning and the unit will shut down. If the pulse still looksgood by the time the circuit activates, you are good to go. If it goes into HV protect, proceed to HVshutdown section to follow.

No HV – Q8038 Not Shorted: Check for 135VDC at Q8038-C. This will verify proper operation of the HVregulator stage. Since the unit is not shutting down and generating an H Stop event in the diagnostics,horizontal drive is being output by IC309. Work your way back from Q8038 to locate where the drivesignal is being lost.

If the voltage at Q8038-C is extremely low or missing, the HV regulator is at fault. Check pin 3 of IC8008.There should be 12VPP pulses with a long duration positive pulse. This indicates the PWM driver isattempting to get proper HV and Q8035 is unable to amplify. If pulses are not present, IC8008 is notworking properly. Verify 12VDC at pin 1 and H pulses at pin 14 before replacing IC8008.

High Voltage Too Low: This is not a common occurrence in this circuit design. PWM regulators will generate lowvoltages if the reference sawtooth frequency or level changes, or if the error loop voltage rises due to pull-downresistors increasing in value. The saw reference is locked to the incoming H pulse and the level is controlledinside IC8008. A quick method to isolate the cause is to measure the voltage at pin 12 of IC8008. If it is higherthan 7.5V, the HV block is defective. If it is significantly lower, check the PWM signal at pin 3. If the positive dutycycle exceeds the negative, IC8008 is sensing the low HV and trying to compensate. Check for clean pulses atQ8038-C. If they are OK, the HV block is defective.

If the negative duty cycle exceeds the positive, IC8008 may be defective. If the duty cycle is near 50%, someonehas managed to turn VR8001 out of adjustment.

101


High Voltage Shutdown: Verification of an over-voltage or over-current condition must be checked first. Monitorthe AC current draw at shutdown to determine which is causing the condition.

Excessive Current: If the AC current exceeds 2A or more immediately at turn-on, begin by disconnectingthe HV block from the circuit. The circuit will still shut down since the error loop for the PWM has beenremoved, but the current level will drop significantly if the block is defective. If the current remainsexcessive, check for shorts on the filament or 200V line. T8004 or T8005 could be defective and can betested by following the procedures in the previous section on replacing a shorted Q8038.

Nominal Current: Either the high voltage level has exceeded acceptable limits or the protect circuits areactivating erroneously. Verify Q8035 is not shorted. The HV block has an extra output port for testing theHV level. Simply remove the cap and insert a HV probe. This is a very important step. If the high voltagelevel is excessive, extra caution must be taken while diagnosing the circuit. Due to the small size of aprojection CRT, it is easy for the high voltage to exit the anode cap and arc to the deflection yoke. Thisusually cracks the CRT. Turn the set on and watch the HV meter for a reading before the unit shuts down.Normal HV should read 31± .40KV. A properly functioning and adjusted protect circuit will trip at 34.5±.50KV so you should be able to see this with the probe.

High Voltage Exceeds 35KV: Connect a DVM with peak-hold to pin 12 of IC8008. The voltage shouldread approximately 7.5VDC. A peak voltage of 7.5V or less indicates a defective HV block or IC8008 isloading the feedback line. If the voltage level exceeds 7.5V by a considerable amount, the feedback loopfrom the HV block is OK and the PWM generator is not operating properly or the tuning components atQ8034 are defective.

To isolate the problem, take a peak reading at the output (drain) of Q8035. If the PWM circuit is operatingproperly, the voltage should be substantially less than the 135V supply. This indicates the PWM circuit isattempting to reduce the HV level. Suspect an open C8123 or C8124 (not shown) at Q8034-C. Fullvoltage at the input and output of Q8035 indicates a short or leakage of this component or an improperlyoperating PWM circuit. Check VR8001 for resistance at the contact wiper to both ends along with areading from end to end. If this VR fails, the high voltage will rise to maximum potential.

High Voltage Reads Approximately 31.5KV: The regulator stage is assumed to be working correctly. Theprotect components are inappropriately firing. If the unit is going into full shutdown, troubleshoot IC8006and its associated components. If the unit is only shutting down the HV circuit, check IC8007 and itscomponents. As illustrated in Figure 25-2, both IC8006 and IC8007 use a 5.1VDC reference at pins 2and 6. Pin 3 of IC8006 monitors a voltage sample of T8005. Pin 3 of IC8007 monitors a HV block samplefrom PWM IC8008. FBT ABL is monitored by Q8028 and Q8029. These transistors are normally onunless FB current becomes excessive and the ABL voltage approaches zero volts.

Check for proper reference level if 5.1V at the inverting inputs of both ICs. If OK, check for voltages at thenon-inverting inputs that exceed 5.1V. If none exceed 5.1V and pin 7 of either IC is high, replace the IC.

102


5

67

+-

3

21

+-

5

67

+-

3

21

+-

D8014MTZJ-5.18

D8013MTZJ-5.18

RV8002

R8102

R8223

R8153

FBTABL

D8038R8099

R8139+15V

FBTABL

R8151

R8157

R8150

R8141+15V

Q8029

Q8028

IC8007

IC8006

D8025D8015

D8023D8016

D8008Q8022

Q8021

R8138

R8142

+15V

+15V

D8043

R8128

TO MAINRELAY LATCH

PROTECT

H PULSELATCH

HVBLOCKSAMPLEFROMIC8008

T8005SAMPLE

FIGURE 25-2 - HV PROTECT CIRCUITS RA-6 CHASSIS 25.2TVP14 7/17/02

103


Chapter 26 - RA-6 Video Circuit Troubleshooting

General DescriptionThe video process circuitry in the RA-6 chassis follows a similar processing path as the RA-5A chassis with theexception on an on-board DTV tuner and decoder. Two NTSC tuners are incorporated along with video inputs1~4 to allow the connection of composite or S video sources. An extra component input has been added (video6) along with video 5, to allow two sources of video up to 1080i resolution. All video sources are selected androuted on the U board.

The A board provides the necessary comb filtering of the main and sub video along with decoder circuits toprepare non-component NTSC sources for line doubling and twin picture processing. It also carries the videoprocessor for RGB conversion to be sent to the CRT drivers. The B board contains the digital processingcomponents, primarily the Digital Reality Creator and Multi-Image Driver.

Due to the Twin Picture feature and Component inputs, several switching stages are incorporated to alter thepath of incoming video. It is these switching circuits along with main, sub and component paths that add to thecomplexity of the video circuit design, but these can be used to an advantage when attempting to isolate sourcesof video problems. Even though board replacement is currently being implemented, isolating which board containsthe failure is necessary and there may come a time when component level troubleshooting is necessary due toboard unavailability.

TroubleshootingFigure 26-1 illustrates an overall view of the video path. All composite and S video sources in the main path areprocessed by 3D comb filter IC6. In the sub-video path, composite sources are sent through a 2D comb filterIC2007. S video is passed straight through to IC306. Both video sources are stripped of sync and chroma sub-carrier by IC303 for the main, and IC301 for the sub. The main will split into two paths, one to the DRC and theother to the MID. Sub-video only goes to the MID to provide a second picture source for P & P and PIP.

104


IC004A/V

SWITCH

IC63D

COMB

IC20072D

COMB

IC303YCTMAIN

IC305YUV

SWITCH

IC301YCTSUB

IC306COMP.

SW.

IC3408MID

IC3410D/A

IC3414YUVSW.

IC3303DRC

IC304A/D

YUV

RGB

IC309VIDEO

PROCESS

R

GB

RGBPJE OSDAD BOARD

IC704MAIN uCOM

YUVYUV

A BOARD

TO CRT DRIVERBOARDS

YUV

YUVYUV YUV

YUV

YUV

SUB Y

SUB C

MAIN TUNER

SUB TUNER

VIDEO 1

VIDEO 3

VIDEO 4

VIDEO 5

VIDEO 6

Y

C

CV/Y

C

Y

C

FIGURE 26-1 - VIDEO PATH RA-6 CHASSIS

CV

A BOARD

U BOARD

B BOARD

26.1TVP14 1477 7/17/02

VIDEO 2

105


Video failures fall into three main categories:

1. No video

2. Distorted video

3. Improper level

Although the video signals are routed through many different paths depending on the type of signal being received,these different pathways can be used to an advantage when diagnosing video failures. The picture & picturefeature provided by the MID circuitry provides a useful diagnostic tool. Since it is able to display two videosignals simultaneously, isolating which stage is causing the problem can be accomplished easily. This featurewill be used extensively in the troubleshooting procedures to follow. Figures 26-2, 26-3 and 26-4 provide moredetailed block diagrams with pin locations and voltages to assist in further isolating where the failure has occurred.

No Video: Two possible causes of this symptom must be ruled out first. There must be high voltage present andthe unit has not encountered an AKB error. Listen for the sound of high voltage and verify it is remaining on byobserving the CRT filaments are still glowing or watch for eight flashes of the timer LED. If the high voltage is notpresent, refer to Chapter 25 for troubleshooting methods. AKB errors will be displayed by the timer LED flashingin sequences of five. AKB troubleshooting will be covered in Chapter 27.

Once high voltage and AKB have been ruled out, try bringing up the customer menu. If it appears, there is agood chance the video process IC309 is working properly. The purpose of trying to get OSD on the screen is toeliminate IC309 as a source of the failure. It could still be at fault since active video enters it via a different input.

The picture & picture feature will be used next. One item that is unique to this new feature design is that HDTVsignals from video 5 and 6 can only be displayed in the left box. Video 5 and 6 will only accept component videosources. NTSC inputs and the two analog tuners will display in either box. If you have a 1080i generator,virtually all of the video processing circuits can be bypassed to further verify the operation of IC309. If you do nothave a HD generator, using the Twin Picture mode with main and sub tuner video will be adequate. By using thisfeature, the main and sub-video paths are displayed together and a wealth of information can be obtained toisolate the video failure.

Video Appears in Right Box Only: The sub-video path is working correctly. An interruption in the mainvideo processing path has occurred. In previous designs, this symptom eliminated the DRC circuit sinceit was bypassed by sending main video from the decoder directly to the MID. The RA-6 chassis will routemain video through the DRC for normal viewing and the Twin Picture mode. The presence of Y signal willneed to be checked at pin C20 of CN13 on the A board to verify whether the problem lies in the mainanalog path on the A board or the digital circuits on the B board.

Video Appears in Both Boxes: The main and sub paths are functioning. The video signal is not beingswitched properly and the MID is likely the cause. Replace the B board.

No Video in Either Box: What is very important at this point is whether the screen remains completelyblank. The MID IC3408 generates a gray background with two boxes for the twin video presentation. Ifthis background information appears and there is no video in the boxes, either a failure of both main andsub video has occurred or the MID is not processing the two video sources. Check CN13, pin C20 on theA board for a main Y signal and sub Y at pin A6 to isolate the B board. Verify proper B+ at CN13 on theA board of 5V at pin A23, 3.3V at A25 and 9V at A27. Replace the B board if present.

If the screen is completely blank and OSD is present, the B board is at fault. Check the voltages mentionedabove before replacing the B board.

Video Level and Distortion Problems: The same procedures used to isolate a “no video” condition can be usedto locate the source of distortion or level problems. With the introduction of multiple A/D and D/A converters anddigital processing circuits, noise in the video is likely to be more common and can take on some strange symptoms.Fortunately, most digital noise problems have a distinct digital appearance. They may be stationary on the

106


IC2004AV SW.

CXA2069Q

8MAIN

RFCV IN

MAINY/CVOUT

44CV : 1V p-pTU2

MAINTUNER

63CV : 1V p-pTU2

SUBTUNER

SUBRF

CV IN

RF CH 13 (480i)75% CB

47MAIN COUT

SUBCV

OUT

53

49

51

1

7

4

CV IN

Y OUT

C OUT

IC20072D COMB

SUBCXD2073

SUB YOUT

SUB COUT

Y : 1.6Vp-p (RF)Y : 1.6Vp-p (V1-4)

56

C : 0.8V p-p (RF)C : 1.2V p-p (V1-4)

58

[SUB] 480i(RF, v1-4)

60

CV : 1.5V p-p

Y : 1.5Vp-p

C : 0.6V p-p

TO 3D COMBIC6

SUB YIN

SUB CIN

CV INY INC IN

CV INY INC IN

CV INY INC IN

CV IN

CV:1V p-pY : 0.6V p-pC : 0.6Vp-p

V1

V2

V3

V4

151719

135

222426

CV (480i)75% CB1.0vp-p

Y/C (480i)75% CB

Y : 0.82V p-pC : 0.62Vp-p

Y, PB,PRV5

Y, PB,PRV6

TO YCTMAINIC303

COMPONENTSWITCH

IC306

TO YCT-SUBIC301

Y PB PR (480i)75%CB

Y: 0.82Vp-pPB : O.53Vp-pPR : 0.53V p-p

Y PB PR (480P)75%CB

Y: 0.82Vp-pPB : O.53Vp-pPR : 0.53V p-p

FIGURE 26-2 - VIDEO SWITCHING RA-6 CHASSIS 26.2TVP14 1474 6/13/02

U BOARD

U BOARD

screen or move around in a clock-like stepping motion. Minor or severe loss of picture detail is caused by one ormore of the parallel bit lines being inactive. The more significant the bit, the more detail loss will occur. Powersupply and external noise will “float” since they are not synchronized with the video. Video level problems tendto occur in the analog processing stages.

Figures 26-2, 26-3 and 26-4 provide detailed blocks with pin locations and video signal levels with color bar inputat 75% white level.

107


84

83 48

Y

C

37,38,39

333435

22,23,24

Y PB

PR

Y PB

PR

CXA2103-1SCON,SCOL,SHUE

(ADJUST RF,VIDEO,& DVD

IC303YCT-MAINCXA2103

YPB

PR

Y/CV C

Y

CIO6

PD64823D-COMB

MAIN

CV : 0.9Vp-pY : 0.7Vp-p

C :0.5V

Y : 0.9V

C : 0.5V

Y : O.7VPB : 0.5Vp-pPR : 0.5Vp-p

Y : 1.2VPB : 1.1Vp-pPR : 1.1Vp-p

BUF

(MAIN) 480i(RF, V 1-6)

1,3,13

154

14

YPB

PR

2,5,12 9 10 11

SELECT PINSY PB PR

Y : 1.1VPB : 1.0Vp-pPR : 1.0Vp-p

IC3090 PIN 9L: 2,5,12M : 1,3,13

[MAIN] 480i(V5,6) DVD

22,23,24

Y PB PR

Y : 1.1VPB : 1.0Vp-pPR : 1.0Vp-p

[SUB]480i(RF,

V1-4)

[MAIN] 480i(RF,V1-6)[SUB] @ MAIN=1080i/480P

YIN

C IN

CXA2103-2SCON,SCOL, SHUE

(ADJUST RF & VIDEO)

46

48

IC301YCT-SUBCXA2103

321

333435

414243

272825Y : O.5V

PB : 0.5Vp-pPR : 0.5Vp-p

YPB

PR

Y

PB

PR

Y

PB

PR

IC306COMP.

SW.CXA2151

Y : O.7VPB : 0.5Vp-pPR : 0.5Vp-p

A19 YC16 B-YA17 R-Y

YPB

PR

C20 YC22 B-YC21 R-Y

88 96

IC2004A/VSW.

[MAIN] 1080i/480P (V5,6)[SUB] 480i (RF, V1-4)

[MAIN] 1080i480P,(V5,6)

Y : 0.8Vp-p(RF)

Y : 0.8Vp-p(V1-4)

Y : 0.4Vp-p(RF)

Y : 0.5Vp-p(V1-4)

Y

C

SUBVIDEOFROMIC2004

A/VSW.

VIDEO5/6COMPONENT

TO BBD.DRC

TO BBD.MID

IC305YUV SW.

SN74LV4053

46

A BOARD

FIGURE 26-3 - ANALOG VIDEO PROCESSING RA-6 CHASSIS 26.3TVP14 1475 6/13/02

108


IC3303D.R.C.

CXD29095Q

Y : 8 BIT C : 8 BIT YPB PR 8 BIT

INPUT SIGNAL 480i ONLY

164-171 122-154174-181

635031

YPB

PR

6-13 17-24

IC33048 BITA/D

TLC5733A

FROMYUVSW.

IC305

PR

0.9Vp-pPB0.9Vp-p

Y :1.0Vp-p

41-11

215210208

44-71

YPB

PR YPB PR 8 BIT

YPB PR 8 BIT IC3408M.I.D.

CXD9509

PR

0.8Vp-pPB0.8Vp-p

Y :0.9Vp-p

[MAIN]480P/1080i(P&P FREEZE) (V5.6)[SUB] 480i(RF,V1-4)

41-11

YPB PR 8 BIT

44,46,42

YPB PR

IC34108 BIT D/A

CXD2309Q

3.2Vp-pDIGITA

L

3.2Vp-pDIGITA

L

3.2Vp-pDIGITA

L

16,11,8 1,14,9

Y PB PR Y PB PR

2 7 12

SELECT PINS IC3414Y PB PRSWITCH

M52055FP

IC704 PIN 52L :16,11,8H : 1,14,9

Y : 1.05V(1.85Vp-p)

PB : 1.05Vp-pPR : 1.05Vp-p

356

YB-YR-Y

Y: 0.5Vp-pB-Y : 0.5Vp-pR-Y : 0.5Vp-p 20

2122

YB-YR-Y

64

63

62

IC309VIDEO

PROCESSR : 2.3Vp-p

G :2.1Vp-p

B : 2.0Vp-p

TOC

BD.s

Y : 1.05Vp-pPB : 1.05Vp-pPR : 1.05Vp-p

FROMCOMP.

SWITCHIC306

FIGURE 26-4 - DRC AND MID PROCESSING RA-6 CHASSIS 26.4TVP14 1476 6/13/02

A BOARD

109

27. Troubleshooting the AKB Circuits

Chapter 27 - Troubleshooting the AKB CircuitsOverviewThe AKB (Automatic Cathode Bias) circuit, often referred to as IK, has been incorporated into Sony televisionsfor many years. In the beginning it created problems for technicians because they were either unaware of it ordid not understand how it worked. The subject was extensively covered in training courses, but the circuitcontinued to be a difficult one to identify and diagnose. This was because the video signal would be cut off, or“blanked”, as the term came to be known.

Why the video is cut off when a problem occurs in this circuit is anyone’s guess. There is no practical reason todo it. In fact, the RA-3 projection chassis did not blank the video when a failure occurred. It did remain blankedat turn on and would display video in approximately six to ten seconds once the CRT cathodes were sufficientlywarm. It would appear that the designers of this circuit intended for the video to remain off until full cathodewarm-up was achieved so the video would appear in a correctly white-balanced state.

The concept of AKB is rather simple. Once proper grayscale balance has been aligned, the circuit will monitorthe current draw of each cathode based on the bias assigned after the adjustments. This will help to maintainproper balance throughout the life of the set as the cathodes age. The current in the cathodes fluctuatesdramatically based on video levels. In order for this circuit to function properly, a sample of cathode current mustbe performed when there is no video and the vertical blanking interval provides the needed area to do this.

The video processing circuits will generate 63us pulses (one horizontal line duration) for each of the RGB drivesignals. The pulses are located near the end of the vertical blanking interval and are slightly above pedestal levelin amplitude and will vary in amplitude based on the drive settings performed in the service mode. This makesthem visible but they will be in the over-scan region of the picture. Each of the primary color drives will have itsown pulse. The location of these pulses will vary, depending on video processor design. They can be movedwithin the blanking interval on some televisions. They are usually located on lines 19, 20, and 21 so this will beused to explain the circuit further. The pulse for the R signal will be on line 19, the green on line 20, and the blueon line 21. The video processor now has a timing reference in order to view each of these pulses as they arereturned from their respective cathode. When a cathode draws more current, the pulse that it received will bereturned at a higher level. The AKB circuit will respond by reducing video drive. The opposite is true if thecathode current decreases.

Each of the pulses returned by the cathodes are combined into a single return line and sent to the video processingcircuit for the AKB section to analyze. Figure 27-1 provides a clear illustration of how this works. It is a diagramof the CG board found in the RA-3 chassis. Since discrete components are used, a clear explanation of how thecathode returns current information can be described. Most television designs, particularly the newer sets, usean IC for driving the cathode(s) and all of the components for current detection are located inside of it.

Q733 provides the necessary pull-down of the cathode bias to control electron emission. The collector is connectedto ground by R743. The more current drawn, the greater the voltage drop across R743. This creates a voltagelevel reference of the current. The voltage drop consists of an AC component since Q733 is driven by a videosignal. This video signal “image” is sent to Q734-B where the signals from the red and blue CRT are merged withit. The signal at this point resembles a composite signal but it is actually a combination of the RGB video,therefore, it is technically not a conventional signal since composite video does not contain the G component.Included in this signal are the three IK pulses from each cathode. Since the video process circuits provided thelocation timing for each pulse, it will simply extract and analyze each one for cathode current level.

When the unit is first turned on, the cathodes are cold and no current is being drawn. The IK pulses at each ofthe RGB drive outputs of the video processor will be high in amplitude since no return pulses are being received.As the cathodes warm up, the output pulses will begin to drop in amplitude as each cathode returns the expectedpulse level. This event is an important tool to use for troubleshooting intermittent AKB problems and will becovered later in this chapter.

110


7

1

3

1

D736

1

FROMFOCUSBLOCK

C732

R732 G2

SG731

Q733

R741

R742

L731

R736R739

+200V

D732

C735

CN731

FROMA BD.CN204

R736

C734

R737R746

Q734

R747

D735

R743

CN732 IkR

IkB

9V

CN737

TO FOCUSBLOCK

C737 R744

CN736

CN735

CN734

TOG BOARDCN503

FIGURE 27-1 - CRT DRIVE (CG)

1

R733Q731R735

R753CLK

C733

D731

Q722

D733 D734

CN733

G

IK

TO CRBOARD CN702

TO CBBOARDCN762

SG7324

1110

9

8

76

5

1F

G1G2

G1kH

H G1 G1

CG BOARD

76

9

97

6

6

7

27.1TVP14 6/19/02

Troubleshooting AKBThe introduction of self-diagnostics was a great feature to assist in analyzing video problems. Prior to that,several checks needed to be made to verify whether the AKB circuit was the cause of no video. The timer LEDsimply blinked at one-second intervals, indicating a problem but not where it was located. High voltage andvertical deflection had to be checked first. The newer models incorporating diagnostics will flash the timer LEDat intervals of five, followed by a three second separator. Any failures in vertical deflection or high voltage willappear in the diagnostics well before AKB is expected.

There are three primary causes for an AKB error to appear:

1. One or more of the cathodes is drawing insufficient or no current.

2. One or more of the return pulses are not making it back to the AKB circuit.

3. The AKB circuit is malfunctioning.

Different approaches to diagnosing this problem are available. Some technicians have developed practicalmethods to accomplish this and should continue using them if they are effective. The troubleshooting steps inthis chapter are a refined process. AKB problems should be located in less than 10 minutes.

111


If you could actually “see” the IK pulses, troubleshooting would be a snap. If the service mode is entered on adirect-view television, the VPOS can be adjusted to bring the picture centering down and the three IK pulses canbe seen as faint lines. If a problem occurred, one or two of the lines would be missing, very faint, or very bright.All three lines could also be either extremely bright or missing completely. It depends on what is causing the AKBproblem. A faint line indicates low cathode emission for that color. A bright line means the cathode is healthy butthe return pulse is not making it back to the processor. If it is successfully returning, then the AKB circuit ismalfunctioning. If all three lines are bright, the IK return line has a problem or the AKB circuit is malfunctioning.No pulses at all would be caused by a failure of whatever is common to the three cathodes, such as loss of G2,no high voltage or no RGB drive from the video processor.

Projection televisions are unique in that the raster displayed in each CRT is not over-scanned. Over-scanning isaccomplished at the edges of the screen behind the bezel. The IK pulses are clearly visible when looking downinto the CRT lenses. This can be an important troubleshooting technique. If one of the CRTs has a missing ordim line, chances are that particular CRT or its video line source is defective.Unfortunately, viewing of the IK lines is not always practical. In a direct-view set, the service mode would needto be entered “blindly” since there is no video to use as a guide. Many models start in the VPOS by default, butothers will begin in HPOS and that would require looking in the service manual and pressing the “1” key theappropriate number of times to reach the vertical centering mode. Looking into a projection CRT is not alwayspractical either. If the CRT is weak, the IK line may appear bright even though it is just below the acceptable levelof the AKB circuit.

The visual descriptions mentioned above are meant to provide a better understanding of how the cathodes candisplay the IK pulse being sent and what the reaction of the AKB circuit is, based on different failures. A moreobjective method involves a simple set of procedures that can be universally applied to projection and direct-viewsets.

No Video - AKB Problem Verified: Check the G2 voltage line for loss due to failure or short to G1. If OK, read theDC voltage on each cathode. NOTE: It is very important to verify that G2 cutoff is set properly for this check. TheAKB circuit will correct for improper screen voltage by increasing or decreasing video drive. If G2 is set too low,the AKB circuit can blank the video. Adjust each CRT to retrace lines and back off until they disappear. On aproperly functioning unit, with no video input and the G2 cutoff set properly, the cathode voltage will readapproximately 185VDC ± 5V. Three possible scenarios will occur with an AKB failure:

1. One of the cathodes reads considerably lower than 185V: This reading will be below 165V. If a brightraster cannot be obtained by turning up the screen control (projection television), the CRT is the problem.On a direct-view CRT, the weak cathode color will be missing from the raster when the G2 is turned up.A weak or dead cathode will cause the AKB circuit to send a large IK pulse and cause the driver to pull thecathode down to try and get a sufficient return pulse. If a bright raster is obtainable, the IK pulse is notreturning to the IK line (highly unlikely), or the AKB circuit cannot recognize the pulse. This is rare, buthas been encountered. NOTE: The above symptom could also occur on two of the cathodes indicatinglow emission. It is unusual but can happen.

2. All three cathodes read low: In a projection television, this indicates a high probability of a failure in the IKreturn line. Since it is unlikely that all three tubes have failed, troubleshoot the IK line after looking into theCRTs for IK lines. On a direct-view set, this can signal a gassy tube. Turning up the G2 will assist indetermining if the problem is emissions related or on the IK return line. Measuring the DC voltage on theIK return line is a good way to detect a potential problem here. The voltage is generally between 2 and 3volts. This line is subject to damage when a CRT arcs and this voltage will read 0V or 5V if this happensdepending on what damage the arc has done.

3. All three cathodes read 185VDC or more: The video processor is not outputting RGB drive, there is abreak in the connection from the processor to the driver circuits or all three CRT drivers have opened.

Intermittent AKB Blanking: This symptom is indicated by multiple AKB failures appearing in the failure history ofthe self-diagnostics screen (if the chassis has this feature). Otherwise, you will have to rely on your own observationor the customer’s description. This can be caused by several possibilities: A weak CRT, intermittent shorts in the

112


CRT elements, improper G2 cutoff or intermittent components, or connections on the IK return line (rare). VerifyG2 cutoff and adjust if necessary. If G2 was set too low, this may have been the problem. Measure the DCvoltage on all three cathodes. If one or two of the cathodes measures less than 170V, it is weak and is the causeof the intermittent problem. On projection televisions, the blue CRT will be the most likely to cause this problem.It usually experiences low cathode emissions first because it is driven harder than the red or green CRT.

If all three cathodes measure 180V or more, suspect an intermittent CRT short. Carefully tapping on each neckcan sometimes locate the short. Getting the customer to describe what the picture looks like when it blanks isalso helpful although they are not always accurate in describing the color. HINT: The green CRT in a projectionset is the most likely to have shorted elements. Since it is pointing straight up, it is more prone to particles fallingand becoming lodged in the gun structure. Pay close attention to the customer complaining of pink, reddish, orpurple colors before the picture loss. This helps to verify a potential G1 – G2 short in the green CRT and is themost common. Any complaints from the customer regarding bright flashes of red, green or blue indicate anintermittent heater to cathode short.

113

28. Auto Registration Troubleshooting

Chapter 28 - Auto Registration TroubleshootingOverviewThe RA-4 projection television chassis was the first to introduce a new registration system for converging thered, green and blue colors of each CRT. The number of course adjustments were substantially reduced. SUB,MID, BOW and 4th-family wave adjustments were eliminated. The number of adjustments was reduced to CENT,SKEW, SIZE, LIN, KEY and PIN. MLIN was added to the RA-5A and RA-6 chassis. Once these coarse adjustmentsare completed, fine adjustments can be performed by pressing the “9” key on the remote and a cursor appearson the screen. Color selection is accomplished by pressing the “3” key. The cursor can be moved around thescreen by using the “1” and “4” keys or by pressing the joystick down to turn the cursor white. In this state, thecursor can be moved any direction with the joystick or position buttons of the remote. Pressing the joystick againwill change the cursor to the selected color, allowing vertical and horizontal shifting of the selected color at thecursor position.

Another outstanding feature of this new design was the placement of light sensors behind the front bezel andoutside the screen area. This feature allows the customer to press a button and re-converge the set should itdrift out of adjustment. It was originally labeled “auto focus” and was subsequently named “Flash FocusTM”. Theposition of each color is memorized by the sensors by reading the offset position, which is performed in theservice mode.

The RA-4 chassis utilized eight sensors; one on each corner and one at the center of the top, bottom, right andleft sides. Later models only use four sensors located at the center of each side of the screen. Since mostdrifting of convergence occurs vertically or horizontally across the screen, the four sensors work adequately toprovide size, centering and skew control.

The RA-4 series housed all of the convergence circuitry (except for the drivers) in a separate plug-in moduleknown as the BD board. In the RA-5A and RA-6 chassis, it is labeled as the AD board. In the RA-3 series, thecircuits reside on the A board.

Convergence is adjusted by entering the service mode and selecting the “PJED” group with the “2” or “5” keys.PJED stands for “Projection Engine Digital”. The lettering at the top of the screen will change from green towhite. Graphics for convergence alignment are generated as RGB signals by the convergence CPU and sent tothe video process IC. Once you are in the PJED mode, between 41 and 86 adjustments are displayed dependingon the chassis. Scrolling through the data settings is accomplished with the “1” and “4” keys of the remote andsettings are changed with the cursor.

Most of the data settings are not adjusted as part of the convergence alignment. About 50% of the values shouldbe left with factory default settings and the remainder will have varying settings based on the stored offset valuesfor the sensors. Only the last seven or eight adjustments are used for alignment.

The purpose of this chapter is to provide some tips on successful alignment procedures and what to do if an errordisplays when the Flash FocusTM is engaged. With the proper knowledge, very accurate convergence andgeometry can be performed which rivals that of a direct-view television.Convergence Tips

Following The Correct Procedures: Proper alignment of the coarse convergence is extremely important for asuccessful outcome. This is particularly true of the height and centering. If they are not properly aligned, theedges (and especially the corners) will develop increased distortions and will require extensive use of the fineadjustment cursor to correct. Severe corner distortions may not adjust correctly because the cursor data reachesits maximum value. The use of an external video source denoting the edges of the raster is recommended toobtain proper size, linearity and centering. If these steps are followed, only minor touchups will be necessarywith the fine cursor.NOTE: Do not use the internally generated crosshatch or dots for centering. The position of this graphic isadjustable independent of the true centering. Most internal patterns are not centered since they are loaded withdefault data and are not used by the factory for alignment purposes. Once proper center has been achieved or

114


verified with a calibrated external source, the internal crosshatch can be centered by changing and saving thevalue of “TPHP” and “TPVP” at the beginning of the PJE group.When replacing an A board in most models, the NVM for the main CPU will be flashed with default data. This isgeneral service data. The convergence data will be located on one or more dedicated NVM chips. In mostcases, the new board can be installed with the default settings. Some minor adjustments will be necessary forvertical and horizontal size and centering along with pincushion. Do not attempt to correct these global settingsin the convergence mode. Edge distortions will occur and high data values will cause excessive drive to theconvergence output ICs, causing them to run hotter. When an attempt is made to write the new settings to thesensor data, Flash FocusTM errors are likely to occur.

Once the coarse alignments are completed, the data must be saved by pressing “MUTE” followed by “ENTER”on the remote. It is recommended to write the sensor offset data by pressing Flash FocusTM before performingfine adjustments. The flash focus sensors are only able to distinguish skew, centering and size on the center ofeach screen edge and cannot detect or correct isolated areas of the screen. It is common to complete a near-perfect convergence session only to see small areas knocked out of convergence after the flash focus memory-write. Be sure to press “mute” followed by “enter” before engaging the flash focus or your alignment job willrevert to where you began. Once the course alignment has been written to the offset data, fine adjustments canbe performed, the data saved and the service mode exited.

TIP: The first item to appear in the PJE adjustment group is “FDIS”. Changing this value from 0 to 1 will displaythe horizontal and vertical data values on the screen for the fine cursor. This is useful in determining if you arereaching the end of the data range for a particular cursor position and this is common to occur in the corners. Itis also valuable when adjusting geometry with the fine cursor when only green is being displayed since thecursor cannot change to white when the joystick is pressed for movement of the cursor.

CRT Replacement: When replacing a CRT it is very important to properly align the main deflection yoke rotation.Failure to do so is a common cause of errors when writing sensor data. With the new CRT installed and the yokeroughly positioned, press, “7” followed by “enter”. The data in the convergence CPU registers will zero out andthe convergence will be severely misaligned. Now that any potential skew correction has been removed, theyoke can be rotated to place the particular color as close as possible to the proper point where minimal skewcorrection is needed by the convergence circuits. Do not be concerned with centering at this time. Align the newcolor as parallel as possible to the other two. Some of the RA-5A and RA-6 chassis contain centering magnetson the CRT and this is the time to adjust them if necessary. The RA-3 and RA-4 series did not come withcentering magnets. If the above steps are followed, minimum alignment will be necessary.

WARNING: Do not save any data while in the “initialize” mode. Pressing “0” – “enter” will read the NVM databack to the CPU registers and restore the picture. Some technicians (and customers) believe that “initialize”restores factory default data settings. All data, including the fine cursor, is zeroed out. The fine cursor alignmentsplay a significant role in vertical linearity and pincushion adjustments. Those who have had to change a defectiveNVM IC in the convergence circuits can tell you how long it takes to re-align the convergence when this happens.Even if all data values for the coarse and fine adjustments and each color were available, it would still take overan hour to enter the values.

High Definition Televisions: With the introduction of high definition and “high definition ready” models, additionalsteps were introduced in the convergence adjustments. Since these models are required to display severalformat resolutions and aspect ratios, raster size needs to be changed to provide the most appealing picture forthe customer. This is adjustable by the customer unless a true HD source is being received in which all controlis relinquished to the incoming signal. Due to the raster size changes (and scan frequency in some models),convergence adjustments must be made in several modes. The data must be saved and the Flash FocusTM

offset data written for each mode. The redundant procedures require additional time for a routine procedure.Convergence is adjusted in the FULL mode, followed by the same procedures in the WIDE ZOOM, ZOOM and1080i modes and must be performed in that order. A 1080i sync source is required for the last mode. TheNORMAL mode does not need to be adjusted. It is the same as the FULL mode with gray borders

115


FIGURE 28-1 - SENSOR LOCATION AND NUMBER

0

1 2

3

Fortunately, the RA-5A and RA-6 chassis have included a new set of instructions known as “COPY” and “ALCOPY”.Convergence is adjusted in the FULL mode, saved and Flash FocusTM offset rewritten. ALCOPY is selected fromthe PJE menu and the data changed from 0 to 1. Pressing “Mute” – “Enter” copies the data from the FULL modeto all the others. The COPY command will perform the same function but will not copy the data to the WIDEZOOM mode.

TIP: Pressing the “DISPLAY” button on the remote while in the PJE mode will immediately engage the “ALCOPY”feature without having to scroll all the way back to the beginning of the PJE menu.

Flash FocusTM ErrorsIt is quite frustrating to receive an error message while attempting to write sensor offset data after a lengthyconvergence session. In some cases, errors occur after minor touchups in the fine mode. In order to obtain abetter grasp on dealing with this situation, it is necessary to have a basic understanding of how this circuitfunctions. Figure 28-1 illustrates the screen and the sensor locations.

Although earlier designs incorporated eight sensors, the four-sensor arrangement is more common, used in allof the newer sets and will be used for illustration purposes.

Sensors 0 and 3 are used for horizontal centering, skew and limited vertical size control. Sensors 1 and 2 areused for vertical centering, skew and limited horizontal size control. It is important to know the numbers of theselocations since they are identified when an error occurs during Flash Focusing. If the model uses eight sensors,the adjustment section of the service manual will illustrate the sensors and their identification numbers.

The convergence CPU generates the red, green and blue boxes that you observe “dancing” at the edge of thescreen during Flash FocusTM. They are technically known as “flags”.

Figure 28-2 demonstrates a somewhat exaggerated view of the green flags displayed while Flash Focusing.The sensors are shown in their normal location outside the screen bezel. The flags do not appear simultaneouslyas shown. They “dance” from side to side and top to bottom. The pair starts near the left side of the sensors andmoves to the right to establish an offset voltage based on the light received by the sensors for each pair of flags.When Flash Focusing in the service mode, the offset voltage is read and compared to the adjustment data youhave written in memory. This will establish the necessary offset data to be written so when the customer uses theFlash FocusTM, the sensors will know where to position each color to the previous service alignment. In thecustomer mode, they will stop when the correct offset is matched to that in memory.

116


FIGURE 28-2 - CONVERGENCE FLAG DISPLAY 1

FIGURE 28-3 - CONVERGENCE FLAG DISPLAY 2

The configuration shown will adjust horizontal centering and skew based on the top and bottom sensors andhorizontal size by using the left and right pair. Vertical centering, skew and vertical size will occur by the flagschanging their position by 90° for the next step as illustrated in figure 28-3. Each procedure is always performedtwice since centering and skew adjustments will sometimes affect size.

The process will be repeated for the red and blue colors and if all goes well, the auto registration alignment willend with no errors displayed on the screen.

117


Flash FocusTM ErrorsThe primary causes of errors appearing during a Flash FocusTM session are:

1. Insufficient brightness level of the flags striking the sensor(s).

2. One or more of the colors “out of range” of the sensors.

3. The flags are being generated out of their normal positions.

The latter usually occurs when someone has altered the data for the flag positions or the data has becomecorrupt. This is only possible on the RA-4W, RA-5A and RA-6 chassis as of this writing. Previous chassisdesigns did not include the ability to alter the flag positions.

Insufficient brightness level errors can occur from the technician turning the picture and brightness levels downduring the registration alignment in order to avoid phosphor damage during a lengthy alignment procedure. It isimportant to return the unit to at least 50% picture and brightness level before engaging the Flash FocusTM offsetadjustment. Sync sources from an external pattern generator will also produce errors. It is recommended toperform Flash FocusTM with the unit set to an inactive channel (snow) with the brightness and picture levels set asmentioned previously. Excessive ambient light can also affect the sensor’s ability to read. Darken the areawhere the television is located as much as possible. The above-mentioned steps will assist in a high probabilityof a successful outcome.

“Out of range” errors occur when one or more of the colors are adjusted beyond the normal read-range of one ormore of the sensors. They are labeled as “overflow” errors in the diagnostics list. This can occur from excessiveskew compensation from a misaligned deflection yoke or misaligned size and/or centering of one or more of thecolors. Errors of this type are the most common to be experienced after a convergence alignment. By followingthe convergence tips mentioned earlier in this chapter, this type of error will be minimized.

On occasion, a technician will encounter a unit in which another technician has improperly aligned the geometryand/or convergence. The customer may have also managed to alter the alignment settings by gaining knowledgeof access to the service mode. In such cases, default settings of global size and centering should be enteredand proper size and centering performed in the PJE mode by using a calibrated external generator. In mostcases, a successful Flash Focus will occur.

If an error occurs during the Flash FocusTM offset-write procedure, it will be prominently displayed on the screensometime during the procedure. The particular color and reason will be displayed on the screen. Table 28-1 liststhe error codes and suggested remedies.

Observing the flags and their position on the screen during the Flash FocusTM event will provide important cluesas to what is causing the error. Under normal conditions, the flags should appear at the locations of the sensorsand be equal in size at the edges of the screen. If something is wrong, one or more flags will be displayed off-centered. It is important to note whether the flags are shifted horizontally or vertically. As an example: If the flagsat the top and bottom are much smaller than the ones at the left and right side, vertical height is probablyexcessive. If the left flag is larger than the right, horizontal centering is off for that color. By viewing the flagsizes, a possible cause of the error is available. If external inputs indicate proper centering and height, flagposition changes may need to be performed in the PJE mode. For those models that have this capability, thefollowing adjustments are provided:

1. VUP: Vertical, upper pattern position. Moves the vertical position for the upper vertical flag at sensor 0.Increase the value to move the sensor down and visa-versa.

2. VMID: Moves the flag position up and down at the left and right sides (sensor 1 and 2).

3. VLOW: Moves the vertical position of the flag for the lower sensor 3.4. HLE: Moves the position of the left flag at sensor 1.

5. HMID: Moves both the upper and lower flag at sensor 0 and 3 for horizontal centering.

6. HRIV: Moves the position of the right flag at sensor 2

118


FIGURE 28-4 - FLASH FOCUSTM ERRORDURING SERVICE MODE

0

1 2

3

ERROR GLO LEVEL S3

FIGURE 28-5 - ERROR CODE STORED IN NVM

PJE 62 213

Color:0 = Green1 = Red2 = Blue

Error Code(See error list)

A single digit change in the data for each option will move the affected flag a considerable distance. Thesealignments should only be adjusted if the flags display unevenly after correct centering, size and skew have beenconfirmed with a calibrated source.

Error CodesFigure 28-4 illustrates what will appear on the screen if an error occurs. This error message only appears whilein the service mode. Any errors that arise during a Flash FocusTM will be stored into the NVM and can be read inthe PJE mode under “PJE ERR”. This is shown in Figure 28-5.

Note: Once an error occurs it will remain in the PJE ERR slot. It can be cleared by scrolling to the error code andmoving the remote control cursor to the left.

119


Below is a list of possible error codes and suggested remedies.

Table 28-1

ERROR CODE DESCRIPTION REMEDY

01 Sensor 0 low output Check if flags are hitting sensor properly. Adjust VUP if necessary. Could be a sensor problem.

11 Sensor 1 low output Check if flags are hitting sensor properly. Adjust HLE if necessary. Could be a sensor problem.

12 Sensor 2 low output Check if flags are hitting sensor properly. Adjust HRIV if necessary. Could be a sensor problem.

13 Sensor 3 low output Check if flags are hitting sensor properly. Adjust VLOW if necessary. Could be a sensor problem.

20 Sensor 0 high output Faulty sensor or associated circuit




30 V center or skew loop overflow

Check mechanical V skew, V center and/or VMID data.

31 H center or skew loop overflow

Check mechanical H skew, H center and/or HMID data.

32 H linearity or size loop overflow Check H size, HLE and HRIV data

40 V center registration data overflow

Check VMID data. Confirm V center data is not near 511 for all modes

41 H center registration data overflow

Check HMID data. Confirm H center data is not near 511 for all modes.

42 V SKEW registration data overflow

Check VMID data. Confirm V skew data is Not near 511 for all modes.

43 H SKEW registration data overflow

Check HMID data. Confirm H skew data is not near 511 for all modes.

44 H linearity registration data overflow

Check HLE and HRIV data. Confirm H center data is not dear 511 for all modes.

45 H size registration data overflow

Check HLE and HRIV data. Confirm H center data is not near 511 for all modes.

50 V center registration data overflow

Check VMID data. Confirm V center data is not near –512 for all modes.

51 H center registration data overflow

Check HMID data. Confirm H center data is not near –512 for all modes.

52 V skew registration data overflow

Check VMID data. Confirm V skew data is not near –512 for all modes.

53 H skew registration data overflow

Check HMID data. Confirm H skew data is not near –512 for all modes.

120


Chapter 29 - Model-to-Chassis Cross Reference

MODEL CHASSIS MODEL CHASSIS MODEL CHASSIS MODEL CHASSIS

KP43T70 RA-3 KP53XBR200 RA-4 KDP57XBR2 RA-5A KP43HT20 RA-6

KP46C70 RA-3 KP61XBR200 RA-4 KDP65XBR2 RA-5A KP51HW40 RA-6

KP48S70 RA-3 KP53XBR300 RA-4A KP53HS20 RA-6

KP48S72 RA-3 KP61XBR300 RA-4A KP53HS30 RA-6

KP48V80 RA-3 KP53HS10 RA-4B KP57HW40 RA-6

KP53N74 RA-3 KP61HS10 RA-4B KP61HS20 RA-6

KP53S70 RA-3 KP57XBR10W RA-4W KP61HS30 RA-6

KP53V80 RA-3 KP65XBR10W RA-4W

KP61S70 RA-3

KP61V80 RA-3

KP43T75 RA-3A

KP48S75 RA-3A

KP48V85 RA-3A

KP53N77 RA-3A

KP53S75 RA-3A

KP53V85 RA-3A

KP61S75 RA-3A

KP61V85 RA-3A

©2002 Sony Electronics Inc.EMCS - A Service Company

1 Sony DrivePark Ridge, New Jersey 07656

Reproduction in whole or part without written permission is prohibited. All rights reserved

TVP140702 07/18/02

, Flash Focus, DRC and MID are trademarks of Sony

TVP14 Training Manual

Documents

troubleshooting techniques

regulator troubleshooting

video circuit troubleshooting

troubleshooting course

video process troubleshooting

video path troubleshooting

new troubleshooting

primary power supply