Originally Posted by paul1981
Jens is right about the caps. I had an A600 that barely booted, and was flakier than a bowl of corn flakes. As soon as I fitted a Kipper2k 4MB memory expansion, all the problems disappeared. This was due to the additional reservoir caps on the aforementioned expansion board.
In that case, you'd probably have the same experience when installing the ACA620. All my new accelerators (ACA1220, ACA1232, ACA620) have large ceramic capacitors added to the VCC rail in order to be compatible with "slightly weak" capacitors on the mainboard. However, you can only do so much in that spot.
If the caps on the mainboard are not 100% OK, you'll experience blinking of the caps lock LED every now and then, keyboard won't work, or the computer will only start properly after a warmup-phase of a few minutes (black screen before that).
It's almost a miracle that our computers still work today. Electrolytic caps are the main reason why electronic devices only barely make it through the warranty period these days.