Kjetil's Information Center: A Blog About My Projects

IBM 6576 Power Supply Repair

Warning: Be careful when working with power supplies, they can contain dangerous voltages even when in powered off state.

I got hold of an IBM 6576-35F Pentium-class personal computer. On power-on, after a few seconds it would go into reset, as indicated by a POST card I had inserted into the ISA bus. The POST codes shown on the card would also differ slightly on each time it was powered on. I disconnected the power supply and measured the +5V and +12V rails and they seemed OK, but when connecting another spare AT-class power supply the system would boot correctly.

I opened up the power supply and saw that the lid of one of the large capacitors had been blown open:

IBM 6576 PSU Old Capacitors

Here is the power supply model information:

IBM 6576 PSU Info

In addition to the blown capacitor there was another identical one, so I ordered replacements for both just in case:

New Capacitors

After making sure everything was discharged (!) I soldered in the replacements and it is now working again:

IBM 6576 PSU New Capacitors

Topic: Repair, by Kjetil @ 03/04-2023, Article Link