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Thread: MV-1FT repair log (and RGBS points)

  1. #1
    H = Hot
    M = Macho
    G = Gay
    HeavyMachineGun's Avatar
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    MV-1FT repair log (and RGBS points)

    Model: MV-1FT
    Symptom: Backup RAM error

    Picked up a parts/not working MV-1FT board. It entered my hands with a missing (lower) backup RAM chip. I checked over the solder pad, looked good, soldered in a new SRAM. Board booted to a backup RAM error.

    Address $D000 Write 5555 Read 0055

    Tried replacing the upper Backup RAM, no change. Checked the enable lines for it, /WE was missing. Patched trace from upper Backup RAM pin 27 to 74HC32 pin 8.

    Board now booted, vertical lines in the sprite graphics. Cleaned slot, no change. Checked over the interconnector for bent pins, none were found. Looked over the board underside with a magnifying glass for gouged traces, found three in the graphics-related area. Patched them, all sprite graphics were fixed. Installed a new battery and played a few games.

    Block diagram of MV-1FT RAMs

    Code:
    ________   ________
    |43256L|   |43256L|
    |Lower |   |Upper |
    |Backup|   |Backup|
    -------    --------
    
    ________   ________
    |43256 |   |43256 |
    |Lower |   |Upper |
    |Work  |   |Work  |
    --------   --------
    Video RAMs are near the 
    Hard DIPs on MV-1FT



    For anyone who wants to consolize this board, the RGBS signals can be grabbed from here. (wires are color coded, white is sync).


  2. #2
    Neo Geo Cup '98
    CloudGamerX's Avatar
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    Nice! Congrats on the CMVS and repair!

  3. #3
    Frenzy Football Player
    GadgetUK's Avatar
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    Great job =)
    My YouTube channel contains some MVS repairs and stuff:-
    http://www.youtube.com/user/GadgetUK164

  4. #4
    H = Hot
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    HeavyMachineGun's Avatar
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    Reuploading pics...




    RGB sources, wires are color coded


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