Ok, I now have an update for my ACA620 problems and I think I know where the problem is.
I tried another PSU and it didn't change anything. I took out the ACA620, cleaned the CPU pins again and reinserted the ACA620 and now it seems to run a lot better although it is still not without problems.
I completed 8 full memory tests (2+11 MB) without a single error and this wasn't possible before. I can also maprom KS3.1 now without that weird chipmemory problem, so it must have been a socket connection problem.
I still think the socket connection seems a bit unstable, and it doesn't touch the motherboard as shown on the attached picture. It is very sensitive to vibrations which is probably why it crashed when I used the FDD.
Currently it seems to be running fine (in WB playing music right now), however if I press down on the PCMCIA connector only a few mm, it crashes.
Last edited by demolition; 02 May 2013 at 16:00.