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Thread: Z80 error?

  1. #1
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    Z80 error?

    G'day i have a board that was working 20 minutes ago and then i switched the machine off for a minute then back on and now all i get on the left of the screen is Z80 error, what does that mean and what are causes of it??

  2. #2
    Lazy SNK Employee
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    OK i'm gunna give a clean i'll be back to let you know!!

  3. #3
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    Gave the cartridge slot a remove and replugged it back together to no avail!!!!
    Can you buy the Z80 chips, it looks like it's the little slotted one that says Yamaha???

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    I noticed there was no sound coming from the board so i reached in to turn it up and on the mv-1fz it's a tiny pot and when i turned it i could hear sound through the speakers when my fingers touched it. Then i turned it off and then back on and have had the Z80 error ever since.
    Could i have shorted something?

    Come on guys i need your help, would i buy a unibios or new sound chip or does a cap kit fix Z80??

    I was going to change the battery in my 4 slot today, but i aint touching it as it's working perfectly!!!

  5. #5
    . SNKorSWM's Avatar
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    Try plugging in a different cart and see if the problem persists. I get that error message occasionally on my 4 slot, and when I switch the carts around in different slots it goes away.

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    Quote Originally Posted by SNKorSWM View Post
    Try plugging in a different cart and see if the problem persists. I get that error message occasionally on my 4 slot, and when I switch the carts around in different slots it goes away.
    No I have tried a few carts now!
    None of them work!!!!
    Even with no cart i don't get the crosshatch, i still get Z80......I have never had this on my four slot, i have had carts not work or have no sound on my four slot but after a clean thet are cool.......this seems dead.

    Anybody, can i replace the yamaha chip, would this fix my problem, or any other ideas??

    What would you do??

  7. #7
    The Mad Jock. IDCHAPPY's Avatar
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    Sounds like the sound chips knacked, but i'm no expert

  8. #8
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    Quote Originally Posted by neo-mvs-man View Post
    Gave the cartridge slot a remove and replugged it back together to no avail!!!!
    Can you buy the Z80 chips, it looks like it's the little slotted one that says Yamaha???
    No, that's the Yamaha 2610. It's the actual sound generation chip, it can do 4 FM channels but mostly PCM. The Z80 is a general purpose CPU that drives the Yamaha sound chip and it will be appropriately labeled on top of the chip.

    To me, it sounds like you're gonna need that chip replaced. This site ought to help you out:

    www.arcadecomponents.com

    If you can't replace the chip yourself, it seems they can do a Z80 repair for a fee.

    Quote Originally Posted by neo-mvs-man View Post
    Come on guys i need your help, would i buy a unibios or new sound chip or does a cap kit fix Z80??
    A cap kit won't fix a Z80 error. Those are only useful for when the sound amp is too low and other similar problems.

    I was going to change the battery in my 4 slot today, but i aint touching it as it's working perfectly!!!
    And then it leaks all over the board and then you're screwed royally...

  9. #9
    JammaNationX
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    A z80 error is a generic error in itself. It triggers when something in the sound circuit is malfunctioning anywere from the Z80 itself (rarely) to the yamaha chip. Sometimes it could be a Neo-D0 and sometimes it's the sram.

    You have to pull out the logic probe and multimeter, check if everything is working correctly.

  10. #10
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    Quote Originally Posted by Xian Xi View Post
    A z80 error is a generic error in itself. It triggers when something in the sound circuit is malfunctioning anywere from the Z80 itself (rarely) to the yamaha chip. Sometimes it could be a Neo-D0 and sometimes it's the sram.

    You have to pull out the logic probe and multimeter, check if everything is working correctly.
    That's where i'm screwed, i wouldn't know where to start.
    could turning the volume dial which is tiny on this model cause a short while the power is on?
    It was working, i adjusted the volume as there was no sound and i wanted to make sure it wasn't turned right down, i turned the machine off to reset it and it's done Z80 ever since even with no cart!
    Can somebody confirm if the mv-ifz throws up this error instead of a crosshatch when there is no cart inserted?

    Thanks

  11. #11
    JammaNationX
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    No, it's fine to adjust the volume when the board is on. Is there any broken traces that you can see? Is it constantly showing the Z80 error?

    Since the FZ is a 2 piece board it is possible that there's just a bad connection between the two. Separate the two boards and then put them back together and see if that fixes it.

  12. #12
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    Quote Originally Posted by Xian Xi View Post
    No, it's fine to adjust the volume when the board is on. Is there any broken traces that you can see? Is it constantly showing the Z80 error?

    Since the FZ is a 2 piece board it is possible that there's just a bad connection between the two. Separate the two boards and then put them back together and see if that fixes it.
    I have done that a few times as i have heard that can cause the fault.....

    And remember it was working, then the game lost sound at some point, when i noticed i tried to adjust the volume (not being sure how high i had it) you could hear through the speakers when my fingers touched the volume knob, kind like when your fingers touch a guiter lead before you plug in the guitar!
    Thers was still no sound, but the game was still running, i turned the machine off to reset it hoping the sound would be back as i have had problems with the sound on that game before (but in my four slot dedicated cab, and the sound has always been fine after a clean of the cartridge).....

    Ever since i have had the Z80 error, with or without a cart and i have unplugged and re-plugged the cartrdige connector a few times as well!!

  13. #13
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    I just experienced the same problem. I'm calling a repair guy tomorrow and I'll post the results when I get a chance.

  14. #14
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    Clear the backup RAM, that will sometimes get you past the error.
    Clowns Suck


  15. #15
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    But how can I do that If I cant even get past the z80 error message? Pressing test mode doesn't work.

  16. #16
    JammaNationX
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    Quote Originally Posted by Lan Di View Post
    I just experienced the same problem. I'm calling a repair guy tomorrow and I'll post the results when I get a chance.
    What board are you using?

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    MVS-4-25 (ver. 3).

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  19. #19
    War Room Troll
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    Well I don't have a unibios yet. Looks like I have to spend money on a repair.

  20. #20
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    There is not a whole lot you can do to track down the problem without a logic probe and/or multimeter. The system saying "Z80 error" does not necessarily mean that there is a problem with the Z80. The last time I had a Z80 error (on an MV-1F board) the problem was that the battery had leaked and ate some nearby traces. I patched the traces and everything worked after that. If you do end up replacing the Z80 be sure to replace it with a Z80A. The original Z80 is overclocked (!) and if you take the trouble to replace it, use a Z80A which (unlike Z80) is meant to be run at 4MHz.
    SNK forever

  21. #21
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    I've decided to use these guys to fix it. I'm kinda broke right now though. I'll wait for my next payday to send it out. http://www.arcadecomponents.com/cata...81/5263405.htm

  22. #22
    Member Specineff's Avatar
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    Hey, I'm having the same problem with an MVF1H a friend gave me, and decided to send it to those same guys for repairs. However, what's the benefit of using a Z80A versus the stock Z80?

  23. #23
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    The original Z80 is rated at 2.5 MHz
    The Z80A is rated at 4 MHz
    The Z80B is rated at 6 MHz
    The Z80H is rated at 8 MHz
    etc...

    The Neo Geo was designed to use a Z80-compatible processor running at 4 MHz. In fact, if you look at the motherboard, it even has "Z80A" printed next to the where it goes. Yet the CPU installed is a Z80. Apparently to save a little money, SNK installed cheaper Z80 chips instead of Z80A chips and ran them overclocked at 4 MHz. I find this rather shocking considering how expensive the Neo Geo hardware was back in the day.

    Rather surprisingly, the overclocked chips seem to be able to handle the extra speed without issue most of the time. Nonetheless, if you are going to take the trouble to replace the original Z80 I would recommend using a Z80A (or Z80B, or Z80H...) so that it is no longer overclocked.
    SNK forever

  24. #24
    Lazy SNK Employee
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    So has anybody had a break through yet??

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