r/pcmasterrace • u/Front_Cookie_1198 • 1d ago

Hardware PSU fails dramatically

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u/Independent-Bug-9352 22h ago edited 22h ago

This PSU turned into a cheap momentary welding machine, and modern inverter welders use capacitors to do the same thing. My guess is 12V rail shorted @ 100-150A, which isn't too far off from welding machine parameters. It's why their circuit breaker didn't trip either, probably still being under 1800W or less from the wall.

They should be turning the IEC cable on from a switch, not plugging it in live from the unit. They should have a circuit-breaker and GFCI inline, and a dim-bulb tester, or at least variac they can slowly dial up.

Also possible this was plugged into a 220V line while the little red switch was set to 110V but I'm not sure if those typically catastrophically fail like this.

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u/Personal_Winter6863 21h ago

Modern PSUs no longer have the little red switch.

They just automatically determine what they are given and run with it.

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u/Independent-Bug-9352 21h ago

No kidding! I just checked my PSU which is even 8-years-old and you're right, no more switch. Older PSU I have running in another still has it!

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u/RealityOk9823 20h ago

Was watching a video the other day and the guy was like "I don't trust these PSUs with a 110/220 switch, they're almost always low quality" and I was like "WTF they all have that". Start looking around and, uh, yeah. Well then.

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u/OkChocolate3501 19h ago

My psus are so old that they never got the switch. I missed an entire gen of nonsense lol.

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u/Personal_Winter6863 21h ago

Haha I also had to run and go check when I learned about this

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u/Alarming-Stomach3902 Linux Mint | Ryzen 7 5800x | 9070 xt | 3060 ti | 32GB 17h ago

They have to be very old at this point, I have a 15+ year old PSU and it doesn’t have it.

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u/Suspicious_Dingo_426 18h ago

Unfortunately, they still do make them.

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u/PlasticSignificant69 15h ago

In hobby and industry it's still widely common. But in typical consumer product it's already rare, because it's prone to human error in the hand of common people

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u/ency6171 i5-4460•2x8GB DDR3•MSI 1070Ti | i7-7700HQ•2x16GB DDR4•1050Ti 13h ago

I was the idiot back then.

Flipped the switch to 1xx, didn't know what's that, and turned on the 2xxV mains.

And of course it went pop.

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u/saladmunch2 17h ago

Like an on off switch?

My seasonic platinum 1000w i got in maybe 2022 does.

The word modern kind of has no meaning to me in pc years anymore.

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u/jonnyGURUgerow 17h ago

This PSU is so cheap, it doesn't have a switch AND it doesn't support 115V. It only supports 230V.

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u/impala_haven 21h ago

By usuing a welder as an example, i now understand how pc's work just a tad more. Electricity is crazy

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u/Strayed8492 21h ago

The trinity of things to treat with absolute unconditional reverence are: The Sea, Fire, and Electricity. There is a graph about electrical potential as energy increase and if I’m not mistaken, it’s exponential not multiplicative.

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u/quarantinedbiker 21h ago

Guy has the Vietnamese flag on his shirt, isn't speaking English, and that PSU looks like it says 180-240VAC right next to the charred bit. I can't find a single reason to believe any of this would be following any North American electrical norms.

GFCI is awesome (I still can't believe whole-house GFCI is not a thing in NA) but it would only have tripped if the case was actually grounded, however I'm not particularly inclined to trust the engineering on that model which is at the very least missing an internal fuse or five. Depending on the type of fault it may not have faulted through the case anyway (at least until the arc reached it)?

Also breakers behave differently depending on the kind of overload, a 100 A load on a 16 A breaker would trip immediately (something to do with the strong magnetic field resulting from a dead short) but a 20 A load on a 16 A breaker might take a while to trip (because it relies on temperature). Which means on a 16/20A 220V circuit you could feasibly pull over 5 kW for a little while. That's more than enough for sustained fireworks.

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u/zepsutyKalafiorek 20h ago

As someone who plugged very cheap PSU with 110/220V switch.

It sparked and I could smell burn but nothing that catastrophic. It could be some combination of problems too btw.

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u/kombucha711 20h ago

This guy electrons

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u/lilsnatchsniffz 21h ago

I imagine if you plugged it in like that at home you'd void your warranty but you send it in and they treat it like shit.

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u/cute_polarbear 20h ago

I understand the individual words but have no idea what you described...

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u/TDYDave2 19h ago

The aftermath photo shows it rated for 180-240VAC.

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u/Alarming-Stomach3902 Linux Mint | Ryzen 7 5800x | 9070 xt | 3060 ti | 32GB 17h ago

It looks like it only accepts 180-240v input. 

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u/LoudFan2771 16h ago

But I thought modern electronic devices only draw as much power as they need. not how much there given. is that not how it works?

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u/Independent-Bug-9352 6h ago

Modern circuits tend to be more receptive to a wide range of voltages and automatically switch, as others pointed out with my comment.

That being said, what you're referring to in more primitive circuits is current draw at an expected voltages. Yes, the device determines the resistance (and thus flow of current), but that's only if the provided voltage is constant.

My last paragraph about 220V is probably not relevant as this is a modern PSU with auto-switching and it looks rated for the top-end voltage as others point out. So we're just seeing a good 'ol electrical short to chassis, presumably.