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Thread: MVS MV2F Battery Corrosion and Vertical Lines

  1. #1
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    MVS MV2F Battery Corrosion and Vertical Lines

    My first post here and hoping to get some advice.

    Steps already taken.
    1) removed battery
    2) vinegar and toothbrush to neutralize and clean corrosion followed by rinse and dry.
    3) continuity check on several traces. Definitely have at least one jumpers to do.
    4) tested on bench
    5) Researched some mvs repair logs.


    Need to do or opinions.
    1) Is there a schematic for this board? I know at least part of the issue is with neo-zmc2 going to neo257s. Would be nice to just verify chip pin to chip pin versus tracing all the through holes.

    2) my test lead on DMM are almost too big to test these tiny pin chips. any recommendations for now and future. Super mini clips?

    3) Here is link to high res pic of at least the one bad trace I have. You can see the neo-zmc2 pads and legs don't look great but I would hate to remove this damn thing. Looks to be a super pain in the ass.
    https://www.dropbox.com/s/9kuctqy33l...23.46.jpg?dl=0

    3.5) if the corrosion is neutralized and I get it working is it even worth cleaning up further?

    4.) Lastly, should I just jumper chip pin to chip pin or chip pin to closest good through hole of trace?
    Attached Images Attached Images
    Last edited by jacklick; 12-16-2017 at 05:09 PM.

  2. #2
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    Geekman1222's Avatar
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    1) Idk if you know about Neo-Geo Development Wiki but it has really GREAT info ! https://wiki.neogeodev.org/index.php?title=Schematics

    3) honestly if it was me I would trace the pin from that via and see exactly where it goes. If the pin is open circuit and or the the trace or via is dead at some point. You can use Magnet Wire, or a component lead or anything really thats thin enough to patch the trace. You can gently scrape away at some of the solder mask on the PCB on the traces you are testing for further testing or to solder a thin wire to if you have no better places to tap into the trace from.

    Since you mentioned battery damage there could have been long term corrosion on the ZMC2 pins and if so it might be messing up your conductivity to the chips pin lead and the SMD pad on the board.
    You could try reflowing solder on the pin lead but if the corrosion is bad it might not be easy.

    Either way I would continuing working with the easy stuff first.

    4) It never hurts to clean a board at least as much as you can. I have fixed several electronics by just cleaning conductive dust and dirt off a PCB believe it or not.

    Good luck

  3. #3
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    pnauts's Avatar
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    is your vertical line is on both slots ? --> NEO-257 output to ZMC2 input (C0 to C31 on ZMC2 side, CR0 to CR31 on NEO-257 side)
    if your vertical line is on 1 slot only, NEO-257 inputs (1 or 2 according to slot)CRxx.

    NEO257 ZMC2
    8 15
    9 19
    11 16
    12 20
    23 17
    24 21
    27 18
    28 22
    40 24
    41 28
    43 25
    44 29
    55 26
    56 30
    59 27
    60 31

    NEO257 ZMC2
    8 32
    9 37
    11 34
    12 38
    23 35
    24 39
    27 36
    28 40
    40 41
    41 46
    43 43
    44 47
    55 44
    56 48
    59 45
    60 49

    chip pin to good trace is ok.

  4. #4
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    thanks for the links, comments and info. didn't get a chance today to mess with it but this will surely help.

  5. #5
    Member xterc's Avatar
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    I had a very similar issue to you in exactly the same area on a 2F motherboard. I replaced the battery and performed an amateur repair job on the tracks (picture shown in link below).

    Let me know if there is something specific you'd like me to check.

    http://www.neo-geo.com/forums/attach...0&d=1505567649

  6. #6
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    CharlieBronson's Avatar
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    Quote Originally Posted by Geekman1222 View Post
    1) Idk if you know about Neo-Geo Development Wiki but it has really GREAT info ! https://wiki.neogeodev.org/index.php?title=Schematics
    thanks for this

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