Looking for advice on a hanging IIGS

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Last seen: 6 years 1 month ago
Joined: Jul 25 2018 - 23:41
Posts: 5
Looking for advice on a hanging IIGS

Hello,
I’ve been trying to diagnose a hanging IIGS.

Symptoms:
After 30mins of play, my IIGS hangs. The screen freezes and a ctrl-Apple-reset goes to a black screen, no boot sound. It never drops to monitor like I think a random crash should do. When I power off and on, the screen shows colored checker board. After sitting off for 10-15 minutes it works again. This is with the chassis closed, and display on top, e.g. hottest config.

With monitor on the side, and chassis open, it never hangs, it has to be an overheating problem. My first thought is PSU.

I reproduced the hang, then immediately opened the chassis to test voltages. I left it on and underload to get a good measurement. Everything looks ok. -5v was a little high at -5.20v, and comes back down to -5.12v after cooling off. Is this enough to crash a iigs? Is it really the PSU?

I also used an oscilloscope to test for noisey DC, but it looks clean.

Any other ideas? All the bus slots are empty. Only card in the machine is a GGlabs 8MB expansion in the memory expansion slot. Next thing I’m going to try is pulling the memory expansion, or running a memory test.

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Last seen: 3 months 1 week ago
Joined: Dec 3 2015 - 20:45
Posts: 63
sounds like the 65816 itself

sounds like the 65816 itself is stopping. you could put an ice cube in a ziplock back to seal it
then when it locks, hold it on the chip a few seconds then try ctrl-Apple-reset to see if it starts again.
You could try cooling the other chips as well.

Larry G

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Last seen: 6 years 1 month ago
Joined: Jul 25 2018 - 23:41
Posts: 5
Thanks, I ordered a new PSU

Thanks, I ordered a new PSU before your reply, but it hasn’t come
Yet.
I tried your suggestion yesterday, but couldn’t get the computer to hang. Another thing I did was finally cut out the old dead battery (ROM 01), but that shouldn’t be related to any freezing.

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Last seen: 6 years 1 month ago
Joined: Jul 25 2018 - 23:41
Posts: 5
My new PSU didn't fix the

My new PSU didn't fix the problem.

I'm taking your advice now. I'm going to use a bottle of electronic freeze spray instead of an icecube, though.

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Last seen: 3 months 1 week ago
Joined: Dec 3 2015 - 20:45
Posts: 63
Be careful with freeze spray,

Be careful with freeze spray, it comes out way too fast and cools too much. I barely squeeze the nozzle and just drip onto the chip.

It seems to leave residue and it's not ESD safe. I just don't like using it.

 

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