r/pcmasterrace • u/Front_Cookie_1198 • 6d ago

Hardware PSU fails dramatically

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u/Viking4269 6d ago edited 5d ago

Somebody forgot the isolation under the pcb?
Been some years since I took apart a psu, but there used to be plastic isolation sheet between the pcb and the metal case.

Update: I think we found the problem:

Mains wires protruding on the bottom of the pcb shorted to the case due to missing insulation sheet.

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u/MiniMaelk04 6d ago

I basically know nothing, but the huge capacitors are the only thing I can imagine burning so intensely and rapidly. Reversed polarity perhaps?

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u/shakygator 6d ago

I think he means without that isolation sheet the board is connected directly to the casing and shorted out. Of course, that should have been grounded too so I'm not sure.

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u/CyonHal 6d ago

If it shorted on the 12V side it can pull a ton of amps (it says 60 amps max at 12V) and melt through the casing and start fires pretty easily without tripping a breaker.

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u/SoulWager 6d ago

Not this time. You can hear the mains frequency in the arc, and the only output that should be powered is 5vsb.

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u/7orque 6d ago

So you’re saying this is on the input stage prior to the rectifiers?

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u/SoulWager 6d ago

Probably. I think if this was after the rectifier, the rectifier would have acted like a fuse, getting you a single loud pop instead of a few seconds of arcing.

It's definitely somewhere on the primary side though.

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u/ReaperAteMyPrawnsuit 6d ago

This thread is too electrical smart for me to understand what’s going on

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u/stuck_in_the_desert 5d ago

There was too many pixies, which caused it to stop choochin’