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Thread: MV-1FZS 5v mod

  1. #1
    Timid Neo Newbie

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    MV-1FZS 5v mod

    Hi,
    I did 5v mod exactly as per http://www.mmmonkey.co.uk/consolised...e-slot-mv-1fz/
    The board (1MFZS) was working fine before the mod but now I get Z80 error when connecting 5v only and crosshatch screen when I also connect 12v... The screen is also flickering badly in both cases (ie. 5v only and 5+12)..
    Could someone tell me where to start...? I double checked all the steps from the instructions and it seems like I did everything right...

  2. #2
    Neo Bubble Buster

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    PDF Mv1Fz 5v mod, Pic 5-page 5, did you cut the trace? its neccesary to cut it.

    If you cut it, the best is you post some pics .
    Last edited by Jarryson; 04-12-2017 at 07:41 AM.

  3. #3
    Timid Neo Newbie

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    Yes i did. I removed big chunk of the trace

  4. #4
    Paris-Dakar Rally Driver
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    ginoscope's Avatar
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    What kind of power supply are you using and is the polarity correct? I did this mod on a Mv1FZ and the only issue I had was that the ac adapter I was using did not have enough power. I think the one that worked for me with all carts was 5v @3A.

    Pictures of the mod would probably be helpful.

  5. #5
    Timid Neo Newbie

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    I'm using jamma power supply... It did work no problem before the mod... I'll try to take some pics of the mod later this evening... But it's pretty much exact copy of the mod in link above... The only difference is that I removed that power amp completely but I think it's not the source of the problem (to make room for stereo mod board)...
    What really bothers me is that when powered with only 5v it gives z80 error but when powered with 5+12 the error is gone (the flickering is present in both scenarios)...

  6. #6
    Timid Neo Newbie

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    Update - the z80 error was apparently caused by the cartridge slot/connector not seated properly..
    Removed and cleaned - z80 error gone. works on 5v only.
    The last thing is the flickering - here's the video...
    https://youtu.be/c9fsQCX3Fmo
    https://youtu.be/ATJ73U-EUDQ
    I double checked the mod, checked solder points with multimeter - all looks OK... Games work, sound works... Any idea where to start...?

  7. #7
    SouthTown StreetSweeper
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    Something's wrong with your V-Sync signal. Chip U2 pin 3 has the TTL-level CSync; check that it looks healthy there.

  8. #8
    Timid Neo Newbie

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    Thanks but... I don't have any logic analyzer... Any way of checking it with just multimeter...?
    And - looking at https://wiki.neogeodev.org/index.php?title=MV1FZS - where's U2 chip...?

    Update: found small piece of s..t between two legs of one of the chips (LSPC2-A2) which shorted them... Removed the bit, burned diagnostic rom and... no errors..
    Put back original bios and... boots up when in service mode (ie. dip 1 on). All tests OK. But when I put the cart in the slot - it does the same thing - flickering... The cart works OK on my other two boards (mv-1c)... Any idea what can be wrong... It appears that the flickering now only happens with the cart in the slot...
    Any idea what is the difference between video output with and without the cart?
    Last edited by brylant; 04-15-2017 at 05:10 AM.

  9. #9
    Timid Neo Newbie

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    OK, fixed the thing...
    For future generations: 330R on SYNC line is not enough for MV-1FZS (although it was OK for MV-1C) and SLG-in-a-box. Added another 180R and works perfectly...
    Other things I have done (and wasted significant amount of time as they all had zero effect on the issue):
    - replaced _all_ caps
    - took sync directly from LSPC2-A2
    - spent hours checking chips/traces/solder points...

  10. #10
    Baseball Star Hitter
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    Hey man at least it was an impressive repair. Good work.
    Looking for UK copies of Dive Alert Becky's Version, Puzzle Link 1 and 2, Gals Fighters, and Pocket Reversi.
    http://www.neo-geo.com/forums/image.php?type=sigpic&userid=41108&dateline=145772  3980

  11. #11
    Neo Bubble Buster

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    Why have you used 330 Ohm for Sync? I use 1K always and 0 problem.

  12. #12
    Timid Neo Newbie

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    I had a general jamma diagram and it was 330R... Obviously it was wrong (at least for mv-1fz). I guess 1k might be a universal value (I'll try it on mv-1c).
    Anyway - problem fixed. Two lessons - start from the basics and don't start by rebuilding the whole system. Positives: I now have all brand new quality caps on the board and it's as clean as it was from the factory...

  13. #13
    Mauru's Zoo Manager
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    this makes me want to trouble shoot my 1c 5vlt mod also thanks. i get no sound ill pull it out and work on it
    I guess it's a good day for Were-Jag... -NG: DEV.TEAM
    It's only fucking 50 USD for crying out loud. -Yakumo
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  14. #14
    Pupil of Bonus-Kun

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    nice work i could of never done that

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  16. #16
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    COLUMBIAN!
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    Quote Originally Posted by brylant View Post
    For future generations: 330R on SYNC line is not enough for MV-1FZS (although it was OK for MV-1C) and SLG-in-a-box. Added another 180R and works perfectly...
    I do not need anything on the sync line for my boards to work on the PVM, why do you need it?

  17. #17

    Neo Alec's Avatar
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    He must be talking about removing the unnecessary audio caps.

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