You're probably right about the solder - I wonder if it's the type they used or environment - because the 50Z PSU had nice shiny solder that the desoldering station took off in seconds when I replaced the caps - made in the same year (1988).
ChipQuik looks like it might be worth playing with at some point.
But I don't want to spend too much time on the Commodore just now, unless I could be sure what was causing the failure.
At least with the battery removed it'll last until I own a scope and have more time. It was just if someone had a working board lying around I'd be happy to buy
It's the PS/2 50Z that I really want to get running. Was running reliably a few weeks ago
Edit: bah, you guys got me interested in the Commodore again. Anyway thought I should test out the Epson 20Mb drive - popped it (and it's WD 8 bit controller card) in to a 386 and it booted right up. The drive only makes noises on seek, it's quiter than your average IDE drive. Anyway boots up "Commodore Electroncs Co." etc (thought that was neat), MS DOS 3.2 with all the Commodore tools like SPEED on it. Ability 1.2, MS Works for DOS, and four game folders containing many games which were made way before my 386 was made - can barely play any of them lol Awesome collection for some of my XT's.
Edit 2: I thought the PSU was fine, but testing voltages showed -11V 4.45V and 11V - could be PSU related.