Hello, I've already posted about this in the introductory section, but for the sake of completeness I'll try to recap everything important in here, and hopefully the experts in this forum will be able to shed some light on the matter.
A few days ago I recovered two MV-1FZ boards in non-working state from a closing arcade repair/reseller shop.
Both of the boards were stuck in watchdog loop. I've been able to fix the first one by repairing a trace and straightening a bent pin which was shortcircuiting a line in the cart riser.
The second one also had an interrupted trace between A8 bios pin and the cpu (corroded platethrough under the BIOS). Patching it took it out of the watchdog loop, but now the board gives me a Z80 ERROR.
Here are the tests i did:
Any idea how can I proceed any further? I ordered a diagnostic cart from Jamma Nation X, to help me debug the Z80, as I'm starting to suspect a defective component (I hope it's not one of the proprietary chips...), but I still feel I cannot completely exclude interrupted traces. Anyone has an idea of what other chip connections I should check? Is there a YM2610 connection table available? Maybe tomorrow I'll double-check the connections again, just to be sure I did not miss anything...
BTW, the board does show some darkening of traces and slight signs of corrosion. The problem was NOT caused by the battery, which was still sane (I removed it anyway, as it is a timebomb).
Advices? Ideas? Things I should check?
A few days ago I recovered two MV-1FZ boards in non-working state from a closing arcade repair/reseller shop.
Both of the boards were stuck in watchdog loop. I've been able to fix the first one by repairing a trace and straightening a bent pin which was shortcircuiting a line in the cart riser.
The second one also had an interrupted trace between A8 bios pin and the cpu (corroded platethrough under the BIOS). Patching it took it out of the watchdog loop, but now the board gives me a Z80 ERROR.
Here are the tests i did:
- Burnt a diagnostic bios, all test passed (couldn't test the Z80 without the proper cart, though)
- Burnt an UNIBIOS 3.0 image and put it in the 1FZ: It plays games just fine... without any audio
- Tested Z80 connections using this table
- Tested 6116 and SM1 connections using the tables found at Jamma Nation X
- Removed the cart riser during tests to avoid potential problems related to that part
Any idea how can I proceed any further? I ordered a diagnostic cart from Jamma Nation X, to help me debug the Z80, as I'm starting to suspect a defective component (I hope it's not one of the proprietary chips...), but I still feel I cannot completely exclude interrupted traces. Anyone has an idea of what other chip connections I should check? Is there a YM2610 connection table available? Maybe tomorrow I'll double-check the connections again, just to be sure I did not miss anything...
BTW, the board does show some darkening of traces and slight signs of corrosion. The problem was NOT caused by the battery, which was still sane (I removed it anyway, as it is a timebomb).
Advices? Ideas? Things I should check?