Ok I think I need some help. The idea was to use the HDD from the IIfx to boot and test the other macs as those came without any hard drives. I kinda misplaced the ROM module of the IIsi, so IIvx it is for now. It doesn't want to boot this HDD. Can you even do that? Is there a floppy image I can write to test these machines?
Ok I'm a bit of a dum dum. This is a 32bit CPU and needs all four RAM Simms populated. Boots now.
The onboard graphics however seemed to be bad. With a pattern that changed if I swapped the VRAM modules around. The ICs on there are ordinary DRAM.
After trying a different video cable it works though. Except the resolution is so weird that even the LCD cannot properly display it, without messing with every setting of that monitor. My CRT is still hopelessly confused. Ahhh, Apple
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That's pretty cool. Too bad that the mechanism in the other drive is jammed.
Today on the bench: heating blankets.
These things are designed to fail after a while. The driver units are super simple.
Failure points here: the caps went bad (they serve as a capacitive dropper to provide the supply for the microcontroller). But also the 10 Ohm resistor burnt itself halfway open and took the thermal fuse next to it with it. I shorted that as a test until I can get a replacement.
These things are designed to fail after a while. The driver units are super simple.
Failure points here: the caps went bad (they serve as a capacitive dropper to provide the supply for the microcontroller). But also the 10 Ohm resistor burnt itself halfway open and took the thermal fuse next to it with it. I shorted that as a test until I can get a replacement.