Help With Mac IIsi - Fail after couple of minutes

[MegaImg]

Working on a Macintosh IIsi for a client. The logic board and power supply unit (PSU) have been recapped. The unit starts up and boots perfectly, but after a couple of minutes, a white screen appears with some bars. The machine has to be powered down manually. I check my work; everything checks OK. Remove the additional memory, test, and remove the add-on ROM, same behavior. Any idea!

If the machine is cold, it will work for around View attachment 87494

 

[dv-]

Has the memory soldered onto the main board been removed or replaced?

If it goes bad it can cause issues - it’s used for VRAM, iirc.

I think you can just remove it completely and just use what’s in the slots instead. But check me on that.

 

[David Cook]

Does the video go bad or does the entire machine crash? If you run something that plays music (or whatever), you might be able to tell if the computer is still running.

Have you run MacTest Pro on the computer? It can test the chips and memory.