Power supply: Still dead

That power supply that I thought was working again after replacing the fuse? Yeah, not so much. I turned it on again a few days later and the ammeter instantly went up to 27A while the output voltage was only around 2V.

Spent some time poking around some more, but it’s been sitting on the table since then. Last week I ordered some μA723 voltage regulators to fix someone’s Astron RS-35M power supply. Since I had a few extras (ordered 10 of them), I popped one into this dead power supply. Fortunately it’s socketed, so replacing it was pretty easy.

Plugged the power supply in, turned it on and much to my surprise, the power supply seemed to be working again! 13.7V at the output and seemed pretty stable.

Thinking everything was good again, I turned the power supply off and unplugged it, put the cover back on, plugged it back in and turned it back on.

Poof, back up to 27A and no voltage.

Well crap.

Went back in, put in a new μA723, turned it on and it was back to 13.7V. Left it running for a few minutes, turned the power supply off, turned it back on a few minutes later and it was back to 27A and no voltage.

Well double crap. So it looks like there is a deeper issue with the power supply that’s causing it to kill the voltage regulator.