G4 (quicksilver?) PSU dying

Hey folks,

it seems the power supply in my dual G4 mac is dying (OF calls it
Apple PowerMac3,5 - I think it is a quicksilver, 2x 800 MHz G4 cpu,
dmesg at https://NetBSD.org/~martin/macppc-atf/dmesg.txt).

Replacement PSUs seem to be unavailable, but several pages I found claim
that I should be able to connect a standard ATX PSU with small modifications.

One minor thing is unclear though: it seems the quicksilver has a +28V supply
(something about ADC graphics or displays) - and I am not sure the machine
would work without that (and no chance to get that from a stock ATX PSU).

Anyone know details or have done that?

Martin