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PSU 18m old Corsair RM550 Gold drawing 32A+ at 230V?! OOPS! :(

Discussion in 'Hardware' started by jewelie, 17 Apr 2016.

  1. jewelie

    jewelie Ancient geek, newbie to BT

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    Hi folks :)

    Well I'm not a happy bunny. With very bad timing (I'm currently losing a battle with Crohns, blargh) our whole PC desk appeared to be dead tonight...

    ...a couple of minutes later I worked out that it was the Corsair RM550 550W Gold PSU that's barely 18 month into it's 5 year warranty and still looks mint. :miffed:

    It has not only died, but done so in a nasty way that I just would not expect of a "quality" component that connects to the mains!

    Firstly, I did a very basic bit of testing with a DMM (yes... whilst completely disconnected from everything, especially the mains) but it doesn't seem to be a simple short-circuit at DC or live to earth fault or anything that obvious. Next, I isolated it from other stuff and nervously connected it to mains alone, it immediately blew the 5A UK plug mains fuse. I tried another, the same, so this is repeatable. Then I wondered if it was a one-off requiring a higher than 5A transient switch-on current for some reason and tried a 13A fuse (very very very carefully with my better half at the fuseboard ready to send the house into darkness) and it knocked out not only the 13A plug fuse but the relevant 250V 32A circuit breaker on household fuseboard too (not the RCD, just the ring main 32A circuit breaker.)

    So when it starts, it attempts to draw 32A+ @ 230V? So there's no fuse or similar basic over current / short circuit protection inside it on the input side? :jawdrop: (EDIT: I was probably wrong about the lack of a fuse, see at the bottom of this post.)

    It's the one component that can bugger up everything else, including our home and lives, so we purposefully didn't get a budget PC PSU (it was £85) hence why I'm very much less than pleased!

    Question: Should such a failure mode, that relies purely on the household's electrical safety protection rather than blowing an internal fuse within the device itself, really ever be seen with a "decent" PC PSU? (EDIT: See below, it probably DOES have an internal fuse.)

    I'd really struggle to have confidence in a Corsair PSU now. :( (EDIT: Feeling a bit better about the idea of an exchange now. :) )

    Warm regards
    Julie

    PS On the upside, at least the HDD and SDD have survived - can't check the rest as I don't have a suitable alternative PSU (not to mention that I'm supposed to be resting anyway.... but rest and sleep are for the dead, lol, and I'm angry right now!)

    EDIT: A chat about this in another thread on another board suggests it probably DOES have a fuse, but given it needs to cope drawing 600W at 120V plus any inrush current, the internal fuse is probably around 10A, so my 5A fuses would naturally be popping before the internal fuse would in such a scenario... my mains plug fuses were protecting the internal fuse. ;) Such an internal fuse would only have gone when the 13A fuse / 32A circuit breaker did... and now it does seem the PSU is properly open-circuit, suggesting a fuse popped inside to protect things!
     
    Last edited: 17 Apr 2016
  2. Xlog

    Xlog Active Member

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    Have you checked for live-to-neutral short?
    Have you tested for shorts at IEC socket or at plug?
    Have you tried another cable on just changed fuses?

    I doubt it drew 32A, was anything else turned on in your house? If yes then it was the combined current draw that tripped the breaker.

    There is always a chance that the fault will happen before any protection circuit, sometimes the protection is designed to short circuit (i.e. surge protection). And that would be my guess - there was a surge or number of minor surges that killed MOVs inside it.
     
  3. jewelie

    jewelie Ancient geek, newbie to BT

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    Hiya

    Of course. But a sensible question to ask. There wasn't one. (Now it's open circuit.)

    IEC socket.

    Changed lead of course; but again, sensible question to ask.

    Yes, there were some other things on on that ring, but not more than about 5A total though.

    I'm aware of shorting as a protection method when used with a fuse. I had assumed from what happened that there wasn't an internal fuse, but I hadn't taken into account the extra current required for running at 110V though. DOH. It worked as it should and my 5A mains plug fuses blowing were probably just protecting the internal fuse from blowing. :p To confirm it, I've checked live to neutral at the IEC socket and it's completely open circuit - I tried reconnecting it with a paltry 2A fuse and it's not blowing it, so it's fair to say that it had an internal fuse and that blew after using the 13A mains plug fuse. :)

    Thanks for the pointers and help. :)

    xxx
     

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