Is this one of those interesting PSUs that has two connections to the motherboard? You can rig an ATX PSU to run it but you'll be running stuff to both motherboard connections and to get soft power you'll need some kind of adapter. I think the PSU is all that really goes wrong on these, but I...
This is incredibly common in long term storage and doesn't just affect Apple gear. I visited Computer Reset and basically everything in the warehouse with a particular composition of foot would have some variation of this fault. It's just the way they degrade in these conditions.
Strictly speaking, the Apple Display Card 8-24 is not a Mac. ;)
But, yes, you need RAM SIMMs compatible with the Macintosh IIfx. You might get lucky on a listing for "LaserWriter SIMMs" but sometimes these are too slow.
but also sometimes not. /shrug
Good luck, these seem uncommon/expensive.
Last I checked, a lot of these files actually still exist on the support website if you know the exact URLs. The site won't give you a directory listing anymore but many ancient direct links actually work fine. I've used archive.org to get the listing and formulate the exact URLs and then...
I've got a spare (but catatonic) IIsi board I can forward to any interested parties if that would be in any way helpful. It has booted within the last year, but currently only either white-screens or death chimes in early boot. I assume it just needs a recap but I have a recapped board already...
Hah, I replaced mine with the 3-AA holder built in to some Wal-Mart LED string lights. Just flip pop in some lithiums, flip the switch to 'On', and tape it there.
This is excellent and will be the perfect replacement for my current ATX PSU bodge job.
For the record, if soft power isn't required, you can carefully pop all of the pins out of the Quadra PSU's connector and the appropriate pins out of the ATX connector (plus connect up some bodge wires to...
Is the immersion method safe to use on these cases? I know some classic Macs have metallic paint inside that reacts poorly to the immersion method. Is the metallic-looking coating in the IIsi case similar or is the plastic just grey inside?