MV1FZS glitches

skylab · Apr 27, 2026

Hi everyone.

I have an MV1FZS board that shows graphical glitches, as visible in the attached photos.
I've already replaced a faulty SFIX ROM with a known good one and verified continuity on all traces from the SFIX ROM to the other chips. The diagnostic BIOS passes all tests successfully.
What else should I check? Thanks.

Darksoft · Apr 27, 2026

Does it happen in all games? did you try that cart on another mobo?

skylab · Apr 27, 2026

Darksoft said:
Does it happen in all games? did you try that cart on another mobo?

Yes, it happen in all games and the cart works fine in another mobo.

Darksoft · Apr 27, 2026

regardless of what the test says, I would check the rams

andydex · May 4, 2026

I had a similar issue when I installed PCBs to consolize my MV1FZ, check the connections between the PROG slot on the cartridge connector and the CN2 connector on the main board. You wouldn't get errors in the diag rom because it doesn't run any tests that far up UNLESS you have a diag cart also.

andydex · May 4, 2026

Actually looking at your photo it seems that it didn't do the Z80 testing so yeah you may not have a diag cart.

Rom1 · May 4, 2026

The pictures shows vertical lines, and FIX layer looks unaffected (unsure, but looks like).

You must check the P bus and the ZMC2.
Issue on the serial lines of the ZMC2 are doing this kind of bugs, but this could also be some CA address lines.

skylab · Jun 26, 2026

Rom1 said:
The pictures shows vertical lines, and FIX layer looks unaffected (unsure, but looks like).

You must check the P bus and the ZMC2.
Issue on the serial lines of the ZMC2 are doing this kind of bugs, but this could also be some CA address lines.

Thanks for your suggestion. I replaced the ZMC2 with the one from a known-good board, and that confirmed it was the faulty component. The board is now working correctly, and after soldering the suspected component onto the other board, the problem, as expected, moved to that board. :thumbsup:

Darksoft · Jun 26, 2026

skylab said:
Thanks for your suggestion. I replaced the ZMC2 with the one from a known-good board, and that confirmed it was the faulty component. The board is now working correctly, and after soldering the suspected component onto the other board, the problem, as expected, moved to that board.

Another happy ending here at Arcade-Projects :thumbsup:

@Mitsurugi-w