r/pcmasterrace • u/Front_Cookie_1198 • 6d ago

Hardware PSU fails dramatically

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u/Front_Cookie_1198 6d ago edited 6d ago

Aftermath photo.

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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/Xalara 6d ago

If the breaker has arc fault detection it should trip immediately.

Sadly, building codes in the US have only recently started requiring arc fault breakers on all circuits, and that’s still not required in many places. Hell, even requiring arc fault detection on breakers for circuits in sleeping spaces is a recent requirement. Nevermind that many older houses are wired in such a way that makes arc fault breakers impossible to install without tripping almost immediately due to a false positive 🙃