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RH265_eng

Apr 03, 2018

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Ionescu Cristina
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    RH265How to add a button table on the front panel

    Idea.The project borns from the development of an alestixs idea, who published the following

    schematics diagram in a foreign forum:

    The execution of the project requires a little of knowledge of electronic assembly and handcapabilities, as you have to build a small pcb and place it inside the recorder.Ill spend no time for preliminar warnings which are usual in such operation, and no time todescribe the basic steps, which I assume known by anyone who is attempting to follow this project.

    Technical informations.As shown in the schematics diagram above, the recorder uses two electric lines to manage thefrontal buttons, line RTN0 and line RTN1. The function of each button is given by the resistor valueplaced in series with it: this resistor is grounded when the button is pressed. Look the originalschematics diagram (without considering the red and blu patches): designers decided to use manyresistors, one after another like in a cascade, connecting buttons in the junction point of theresistors.In my practical execution, I preffered to plan a resistor for each button, rather than many resistorsin cascade, to make each button indipendent and to allow its function to be simply modified, also ina second time, by changing the value of its resistor.In this table youll find all the functions avilable for each line, with the relative resistor value,sperimentaly discovered, and the one you can get with standard value resisotrs.

    (*)Note: Resolution button doesnt work in this recorder.

    Fuction Resistor value Standard value

    RTN0Open / close 0 0 Channel + 680 680 Play 2700 2700 Stop 6400 5600 + 820 Rec 9700 8200 + 1500 Resolution (*) 14400 12000 + 2200

    RTN1

    On / Off 0 0 Channel - 680 680 Hdd / Dvd 4200 1000 + 3300

    Time shift 6400 5600 + 820

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    Hardware mod.First you have to build a small board which will be placed inside the recorder, under the existingbuttons.Since I didnt know, at the beginning, my preffered buttons order, l designed the board in aparticular way, which would allow me to connect each button to any line, just changing the positionof its resistor on the board. I also planned on the last button, in place of a fixed value resistor, avariable trimmer, I used to look for the proper value of the other resistors.

    My board is 92 mm large, 16 mm high, and contains nine buttons, with a distance between centersof the button pins of 10 mm.

    Once youve choosed your preffered buttons order (in my case, starting from right: Open/Close |Hdd/Dvd | Channel - | Channel + | Play | Stop | Rec | TimeShift | Resolution ) and selected thevalue of resistors like stated in the table above, you can solder the components on the board,which, at the end of your work, should look like this:

    Note:The variable trimmer on the right, althought showed to be mounted vertically, must be solderedhorizzontally.

    Please give a look to the position of the resistors over the buttons: if placed in parallel to thebuttons, resistors are connected to line RTN0, if obliquely, resistors are connected to line RTN1. In

    this way its possible to choose, and modify later in accordance to your taste, the function of eachbutton.

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    The three pins connector placed on the right of the board, isintended to connect the lines RTN0 e RTN and GND.Its pinout is showed in the picture.

    The mentioned lines go to the original pcb of the recorder, placed inthe rear of the front panel, and must be connected by three wires,to be soldered where showed in the following pictures.

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    Front panel mod and installation of the buttons table.This was the step I found more difficult, especially to get a good result, aesthetically nice.First, I deleted from the surface of the front panel any written references to AV3 input, with a wadof cotton soaked in acetone (sure, the liquid used to clean nails the other diluents I testedwerent able to remove references).Then I punctured the front panel, to allow the button pins to pass through the plastic.

    Starting from right, I made the first hole at 19 mm from the lateral edge and at 11 mm from themiddle line bending of the panel. I aligned horizontally the other holes, with a distance between thecenters of each hole of 10 mm.In this way the buttons table isnt centered with the three existing buttons, but appears shifted tothe right, behaviour needed to preserve the integrity of the plastic supports placed on the rear ofthe front panel.

    Obviously, the diameter of the holes varies depending on the diameter of the buttons, in my case,the pins were 3 mm, and so I practiced holes of 4 mm to leave a little space around.

    Before fixing the buttons table, I wrote on the surface of the front panel some references todescribe the function of each button.I had no other choice than using transferable adhesive letters, which I applied with great patience afew millimeters over the holes of the buttons, and under AV3 input.

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    To avoid unwanted removal of the references, I spried the bottom part of the front panel, untill themiddle line bending, with a transparent acrylic paint.As the paint I used was glossy, I passed one last light hand of paint, keeping the jet very inclined todeposite only a few particles of paint, in non-uniform way, obtaining an opaque reflection effect

    similar to the original color of the panel.

    Then I fixed the buttons table to the rear of the front panel, with some hot glue, being careful tokeep the axis of the buttons pins perpendicular to the panel surface and perfectly in the middle ofholes.

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    It is necessary to avoid points of contact between the buttons pins and plastic, as they wouldprevent the free movement of the pins, thereby obstructing the operation of the buttons.

    Now, you have only to connect the three wires to the connector in the right side and to restore theoriginal recorder pcb, making a small slot in the lower left corner in order to escape the screwadjustment trimmer, being very careful not to damage the tracks.

    The buttons table is almost covered by the original pcb and is placed under it.

    Final result.Reassembled the recorder, you can enjoy with satisfaction the achieved result.

    GOOD WORK!