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MVS 2 Slot Woes Sound Glitching Audio Issues

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  • MVS 2 Slot Woes Sound Glitching Audio Issues

    Heya guys I sure hope someone can help me with my 2 slot problem. So I bought an MV2 A and MV2F to restore to sell one and keep 1 for myself.
    MV2 A - Has audio distortion, please see video link:
    Slot 2 outputs no sound at all, it outputted sound perfectly at one point then suddenly crapped out.

    - I have: cleared backup ram, recapped board, cleaned volume sliders, ran DiagRom, no errors (Awaiting on DiagCart to perform full z80 testing)

    MV2F- Has a very similar audio distortion to MV2A. The difference is that there are no output to speakers, only the headphone socket.

    -I have: performed the same repairs above but with the addition of swapping out YM3016D, YM2610, HA13003 for know good components and this had no effect.

    Both boards I have looked at traces and reflowed suspect looking joints. The boards seem to be in excellent condition ( they have been is storage for 15 years and used to work fine (according to the seller) No evidence of burnt or coroded traces.
    On both of the boards the image is absolutley wonderful. It's nothing to do with the cart or the cab as these work pefrctly in my other 1 Slot MVS

    I've spent around 18 hours on these boards and I am getting to the end of my tether so If anyone can assist, please help 😀

  • #2
    Dunno if it will help the this site has around 19 pages of Neo Geo repairs

    http://newlifegames.com/nlg/index.ph...topic=1859.360

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    • #3
      Originally posted by iborg View Post
      Dunno if it will help the this site has around 19 pages of Neo Geo repairs

      http://newlifegames.com/nlg/index.ph...topic=1859.360
      That's me.

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      • #4
        Originally posted by TobiasRieper View Post
        MV2F- Has a very similar audio distortion to MV2A. The difference is that there are no output to speakers, only the headphone socket.
        Audio caps. Don't mess with the HA13003. They rarely ever fail, but the audio caps are well known for being shite and causing low or no audio out or audio missing from a channel and even for the audio to repeatedly thump badly and kill power supplies. (TK brand caps suck) The thump is an audio oscillation and is bad enough that it can cause large current draws on the +12v line to the point the 5v line will sag and reboot the game. That high current pull will kill a power supply if left on..

        So... there are 2 bits of audio on the NG... audio generated by the FM synth function and then audio samples.

        First, clean the slots. Next, check the ports on the YM2610 for activity - you're looking for lines with missing signals.

        Click image for larger version

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        The schematics are hard to read and fuzzy... but at least that's what's available.

        Trace the missing signals back to a custom (NEO-257, IIRC)... then back to the slots.

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        • #5
          Originally posted by channelmaniac View Post

          Audio caps. Don't mess with the HA13003. They rarely ever fail, but the audio caps are well known for being shite and causing low or no audio out or audio missing from a channel and even for the audio to repeatedly thump badly and kill power supplies
          Thank you for the advice channelmaniac . I did read all through the 19 pages on your website regarding MVS repairs. I will trace those signals you have specified; now I know where to look

          Today I made and used SMK Dan's Diag ROM and Diag Cart to run diagnostics on both boards. MV2F returns no errors. The only thing I haven't swapped out on that board is the Op Amps...those are coming Monday/Tues.
          MVS only has Audio (through headphones socket) on slot 1 and that's all distorted.

          After cleaning cart ports again with iso and cotton swabs MV2A started behaving. I get Audio albeit crackly and distorted on sounds that are certain frequencies (not the neo start up jingle) slot 2, I cannot hear anything from either outputs.
          Last edited by TobiasRieper; Yesterday, 04:27 AM.

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          • #6
            Originally posted by channelmaniac View Post

            That's me.
            Thanks for documenting these its helped me in the past.

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            • #7
              Thanks guys, glad you found those logs helpful.

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              • #8
                Originally posted by channelmaniac View Post
                Thanks guys, glad you found those logs helpful.
                . I swapped the op amps today and cleaned the slots again with iso n cotton swabs. After repairing a trace I get sound from speakers now on MV2F.

                Odd thing is channelmaniac sometimes I get sound out of slot 2 and others I don't (both boards) UPDATE: I heard this was a problem with UniBios 4. .
                Could it be I have a bad 257?
                Last edited by TobiasRieper; Today, 09:22 AM.

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