I've got a faulty CPS2 A-board which works fine except the sound is all wonky.
In particular, the music seems the most affected, although I'm not convinced the sound samples play correctly either (no whiff jab sound effects?).
Here's a vid which shows the issue:
I know it's a problem on the A-board. I've swapped the Z80 chip, the PALs near the Z80, and even swapped the Q-sound chip (which took quite a bit of doing!).
I'm after further thoughts and opinions on where to try next. I have plenty of donor boards for parts.
My suspicion is either some faulty LS chip in the circuit (however testing these in-circuit with the CPS2 2-layer setup is nigh on impossible), or possibly the custom CPS-A chip that also dies on all the CPS1 boards. I'm not particularly familiar with the audio circuit of the CPS2, and can't find a schematic.
Any help appreciated!
In particular, the music seems the most affected, although I'm not convinced the sound samples play correctly either (no whiff jab sound effects?).
Here's a vid which shows the issue:
I know it's a problem on the A-board. I've swapped the Z80 chip, the PALs near the Z80, and even swapped the Q-sound chip (which took quite a bit of doing!).
I'm after further thoughts and opinions on where to try next. I have plenty of donor boards for parts.
My suspicion is either some faulty LS chip in the circuit (however testing these in-circuit with the CPS2 2-layer setup is nigh on impossible), or possibly the custom CPS-A chip that also dies on all the CPS1 boards. I'm not particularly familiar with the audio circuit of the CPS2, and can't find a schematic.
Any help appreciated!
