Good Morning everyone; I have a sound issue with a Time Machine as well and I'm trying to pickup working on solid state pins. I have some experience with electronics but it is pretty shallow. I have fluke meter, can desolder and socket chips, check resistors, diodes and transistors but that is about it. I can burn 27C64, 27C128, 27C256 and 27C512 EPROMS using an older burner and know my way around a hex editor a bit.
Logic probe is on order.
Time Machine was obtained dead with a missing 5V power board. I replaced the board, did some repairs to the PPB, replaced the cooked GI connectors and after reseating the MPU Eproms it came to life. (To keep from confusing the issue further there we should ignore the scrambled displays) worth mentioning as I can't get into or have feedback via displays from the onboard diagnostics.
I have no sound during gameplay at all, voices, music nor effects. Chimes and knocker work if you "get to the 50's"
When the machine boots up it does state "Time Machine" nice and clear which would make me think at least the sound board is functioning yes?
Sounds like a silly question, but how do you isolate a sound board not responding to the MPU vs a possible MPU not putting out the correct signals to the sound board? I'm ASSUMING the MPU Eproms are working proper as the machine works and the PIA light is out.
The sound board has 12+/12- and 5+ voltages verified. I have pulled all the socketed chips off the board, made sure the legs were clean and reinstalled which did nothing. Tried flipping the data cable, no change.
It states "Time Machine" on start and that is all you get. Before I head over to Mouser to order a handful of new capacitors on general principle is there anything else I can check with the tools I have on hand? Thank you for your time! I'd really like to save this one, it was sitting in the back of a van in a cornfield as odd as it sounds.