Elfen said:

Leaky caps and a bad Signal Diode in the PSU. Can you do a jump start with a battery like on the Mac IIs? You need to set up the + battery wire on the PSU output and then touch ground.

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Going to be tricky to try the battery trick. When the motherboard's installed the battery and power connector is blocked on motherboard side. I could only access the power supply on top if I unplug the motherboard cable.

I'd have to see about trying to flip the motherboard over to access everything and test there.  Is this pinout right?  Hard to actually find power supply pinouts

orange.... +12 

blue.... -12 

yellow.... +5 trickle 

white.... power on 

red.... +5 

black.... Gnd