I've got a IIgs that had been working fine; last night, while booting, it presented an "Unclaimed Sound Interrupt" error. I tried every troubleshooting option I could find online (removed peripherals, reseated chips, etc.) to no luck. After running the built in diagnostics, I ended up with a $0C000001 - Sound RAM data error issue.
It looks like the Sounds RAM chips are not socketed so there's nothing to reseat. I inspected the board front and back and don't see any obvious issues. Any suggestions on what to try next?
The problem occurs even with no peripherals at all, or with any combination of memory expansion, drive, and ADB keyboard.