8100 psu

[imactheknife]

Picked up an 8100 case with supposedly working psu. Item arrived no power. So thought well why not recap it, it definitely will need it. Still nothing.. sucks that it was sold as working. Any suggestions?

 

[imactheknife]

Figured it out.. all good!

 

[kurb69]

What ended up being the issue?

 

[imactheknife]

What ended up being the issue?

When i recapped it i noticed a resistor that had looked warm at the solder joints. I reflowed the solder but inadvertently broke the trace. After trying and it was dead I checked all my work and that resistor and noticed it moved a little when touched so checked continuity and sure enough the trace was broken. Soldered a leg from radial cap to the place it is supposed to connect to and ahe lived again.

 

[Durosity]

On a side note, if you ever need a new PSU for a 800/840/8100 there’s this project that @croissantking has made

Thread 'New PCB design: 840AV/8100 Stealth ATX'

Apr 5, 2026

I wanted to share this layout for a brand new PCB that I've just about finished, one of my first proper designs.

It is intended to fit like a glove inside the Delta power supply housing that's common to the Quadra 840AV and Power Macintosh 8100. These PSUs are failure-prone and notoriously difficult to repair, so I was keen to come up with a classier solution than just stuffing an ATX PSU inside the case with an adapter and calling it a day.

The new PCB replicates the exact dimensions as the original Delta lower PCB. It's designed to have the internals of an ATX power supply stood off...

• croissantking
• Replies: 19
• Forum: NuBus Power Mac, LC & Performa