Dropwire
Kuroko's Training Dummy
- Joined
- Jul 27, 2018
- Posts
- 75
Hello all, working on an MV1FZS this time and trying to chase down the cause of the dreaded Z80 error.
I have watched the great video on "Z80 Error from Hell" (https://www.youtube.com/watch?v=3FAHJmtqIKM&t=32s) that GadgetUK put together. Unfortunately the board he was working on MV1A has a different configuration than the MV1FZS. The MV1FZS does not utilize the Neo-BUF Chips. With that being said, below are my findings so far:
Using the Diag Bios and Diag Cart, I get Z80 dead comm. Expected "C3" Actual "00".
- Repaired several broken traces
- Replaced the "Z80" with a worker from another board, and also tried a "New" Z80 that I ordered.
- Replaced the YM2610
- Replaced the NEO-D0 (from a donor board)
- Replaced the SM1 (from a donor board)
- Replaced the Z80 Ram (from a donor board)
- Checked continuity between Z80 / D0 / C1 / SM1 / Y2610 / RAM
- Checked Logic Levels and then compared them to Logic Level from a working MV1FZ (closest thing I have to a MV1FZS). Seeing differences in levels for the Z80 Pins 1 ~ 5 (A11 ~A15) Pin 9 (d5) / 13 (D7) / 18 (Halt) / 22 (WR) / 37 ~ 30 (A7 ~A10)
- Also seeing differences in the Logic Levels for the SM1 / Z80 Ram
- Thinking there may be a NEO-C1 issue, but not sure how to proceed with this one. I don't have any spares to try and swap one in.
- Using the Uni-Bios I can bypass the Z80 and all games play fine, did this just to make sure there were no other issues with game usage / game play.
Thoughts, Ideas, or if you want to send my some alcohol that would be great too.
Thanks...
I have watched the great video on "Z80 Error from Hell" (https://www.youtube.com/watch?v=3FAHJmtqIKM&t=32s) that GadgetUK put together. Unfortunately the board he was working on MV1A has a different configuration than the MV1FZS. The MV1FZS does not utilize the Neo-BUF Chips. With that being said, below are my findings so far:
Using the Diag Bios and Diag Cart, I get Z80 dead comm. Expected "C3" Actual "00".
- Repaired several broken traces
- Replaced the "Z80" with a worker from another board, and also tried a "New" Z80 that I ordered.
- Replaced the YM2610
- Replaced the NEO-D0 (from a donor board)
- Replaced the SM1 (from a donor board)
- Replaced the Z80 Ram (from a donor board)
- Checked continuity between Z80 / D0 / C1 / SM1 / Y2610 / RAM
- Checked Logic Levels and then compared them to Logic Level from a working MV1FZ (closest thing I have to a MV1FZS). Seeing differences in levels for the Z80 Pins 1 ~ 5 (A11 ~A15) Pin 9 (d5) / 13 (D7) / 18 (Halt) / 22 (WR) / 37 ~ 30 (A7 ~A10)
- Also seeing differences in the Logic Levels for the SM1 / Z80 Ram
- Thinking there may be a NEO-C1 issue, but not sure how to proceed with this one. I don't have any spares to try and swap one in.
- Using the Uni-Bios I can bypass the Z80 and all games play fine, did this just to make sure there were no other issues with game usage / game play.
Thoughts, Ideas, or if you want to send my some alcohol that would be great too.
Thanks...