Shorted Macintosh II Astek Power Supply

[LeSpameur]

I was recently given a non-working Macintosh II power supply to repair and use with my Macintosh II board. Someone already recapped it correctly, and every capacitor has the correct value.

It tries to start but immediately shuts off, and the fan doesn’t turn on. When I keep holding the power button, it goes into a loop.

I quickly found that the power supply is shorted to ground, but I can’t figure out where.

I have no experience with power supplies at all, and I know it would be easier to swap in an ATX power supply, but I really want to improve my repair skills!

I found the schematics on Macintosh Repository : https://www.macintoshrepository.org/28276-mac-ii-power-supply-schematic

 

[mitchW]

Which voltage rail of the PSU is shorted to ground? Are you sure all of the capacitors are oriented right way ?
Is your motherboard known good (tested working)?

 

[LeSpameur]

Which voltage rail of the PSU is shorted to ground? Are you sure all of the capacitors are oriented right way ?
Is your motherboard known good (tested working)?

Hi,
Sorry for the late reply, I ended up going with an ATX conversion.