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Thread: MV-1C Player 1 A button not working

  1. #1
    Timid Neo Newbie

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    MV-1C Player 1 A button not working

    Hi all,

    got a MV-1C board I picked up off ebay with the intention to 'consolise' it and for some reason the A button for player 1 is no longer working.

    I haven't got too far with this project yet and was simulating controller input by grounding the necessary jamma pin in order to navigate the bios/hardware test menu. Intially I was able to select hardware test (using button A) and then press start to change from the grid pattern to colour test but now the A button no longer functions (confirmed by trying a game in the unit).

    I traced the jamma pin for button A to the capacitor resistor network the input and output output go low when I press A, traced from the CR to a pin on the NEO-YSA2 which also goes low when pressing button A.

    So it would seem the necessary input is reaching the chip, unfortunately there is no pin out for the YSA2 or schematic specific to the MV-1C (that I can find) so should I just assume the chip is buggered?

    cheers for any enlightenment you can offer!

  2. #2
    Timid Neo Newbie

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    No pointers at all?

    I'm not entirely sure what is going on inside the NEO-YSA2 chip so no idea if it's at all possible to bypass the fault in any way or is it just a case of repair by replacement of the entire chip (which basically means acquiring a full replacement board anyway.)

  3. #3
    Crossed Swords Squire

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    If you are getting the proper signal up to the chip, but not out of the chip, it's reasonable to believe it is the chip that is causing your fault.

  4. #4
    Timid Neo Newbie

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    Quote Originally Posted by MobiusStripTech View Post
    If you are getting the proper signal up to the chip, but not out of the chip, it's reasonable to believe it is the chip that is causing your fault.
    I agree but wanted to be totally sure before making that judgement. There is no pin out or real details on the YSA2, is there anyway to actually check the output from it (so to determine if the chip is at fault or from the chip to the next component assuming there is one?).

  5. #5
    Crossed Swords Squire

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    If you were able to determine the out pin then obviously checking that. Aside from that, not really because you are losing scope of the signal once it enters the chip.

  6. #6
    Timid Neo Newbie

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    Yeah I may have to just call it a write off then as I have no idea which if any of those pins output anything let alone if I can bypass/emulate the YSA2 operation for the A button

  7. #7
    JammaNationX
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    If the resistor pack is good and outputting and it reaches the YSA2, then replace the YSA2. It happens, that's why I make sure they fully test boards before I buy because the YSA2 is an important chip.

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