Hi everyone! Long time lurker, first time poster. I'm working on bringing a Supermac UMAX C500 (603e/160) back to life. The machine would not reliably output video on boot (even after a new battery and removing extra RAM). I was able to get the grey screen twice through various CUDA resets and general witchcraft efforts, but the mouse would move for a moment, then hard lock. After stripping the board bare except the cache module (they're difficult to remove) the problem persisted. Once I removed the cache module, the machine has very reliably booted every time since.
I have found the wonderful reference over at:
(thank you for that!) and it appears that I have a 35_25_20 pinout (pictures below) 256k module. I have reproduced the boot issue by putting the module back in, and resolved it again by removing it - I'm reasonably confident I have a bad module. Aside from eBay (which I've already scoured to the best of my ability), is there a way to get a new/replacement module (maybe even a larger 512k or 1MiB?) from a reliable source?
Thanks in advance for any advice you've got!
-Sam