Amiga 3000 replacement power supply

[mechy]

Unfortunately neither of those options help unless the converter has a voltage converter circuit on it. No -5v on that supply either. Does anyone have a link to a known good circuit for +5 to -5v?

I don't have a circuit, but i have done this using a 7905( i think!) regulator and some filter caps long ago. the -5 needs very little amperage. The input will be +12,not +5 though, you can't go from +5 to -5 since there are losses etc(one exception may be a dc to dc converter).It doesnt make the cleanest -5v,but seemed to work ok.
I think you would be better off finding a proper full atx psu with -5,which is a bit harder these days.

Have you considered fixing the original 3000 psu?

[mechy]

You can't regulated a positive voltage to a negative voltage easily.

You can however regulate the -12volt down to -5volts, simply using a 7905 regulator, and a few capacitors.

oops, you are right, my memory is worse than ever!.

[mechy]

I have but don't know where to start. I've looked at other threads but they were for nonfunctional supplies. In this case, it's working and putting out correct voltage, at least with low demand. My guess is as I add demand it starts to drift out of tolerance. With just the mb, floppy and he attached it seems to work except for an occasional wobbly screen from Amber until it warms up. If I wanted to do a complete rebuild what components would I need to replace?

Just a guess but since the psu is working, its more than likely bad capacitors. You might consider replacing them all. be sure to use low ESR types where needed.

I guess you have reseated the amber chip(checked for clean pins/socket) and also the adjustment pot for the flicker fixer could need adjustment.