Mac LC Weirdness - Electric Charge? Shorting Out?

[Scott Baret]

I have an LC, both logic board and PSU re-capped, with a strange issue. The logic board appears to build up some sort of weird charge over time. It causes video interference over time and today caused the computer to short out while starting up. I unplugged the PSU from the board, re-inserted it, and it's fine now. It probably will have the video problem again a week from now. Any thoughts on what could be causing this? Monitor is not the issue; it has been tried on another LC with no problems.

History of the board: before it got re-capped, the board had a video issue. It was related to caps. The board was re-capped in 2016 and worked flawlessly until the video interference issue showed up about 9 months ago.

I have a few extra boards to try tonight to rule out the PSU.

 

[AwkwardPotato]

... and today caused the computer to short out while starting up.

What exactly happened when the computer "shorted out"?

This sort of sounds like a PSU problem. Was every cap in the PSU replaced? Some guides say to only replace a few, which is false.

 

[Scott Baret]

When I started the computer up, it kept restarting every few seconds and the hard drive would start to spin down.

 

[AwkwardPotato]

Almost certainly a power supply issue, then, given that the hard drive starts spinning down.

 

[Scott Baret]

Popped a spare in and ran it for 20 minutes. No problems.

The hard drive also failed to spin up two weeks ago. It worked fine today.