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LOMS Incident - Habemus plus vis computatoris quam Deus
Ramblings of a Unix ronin
unixronin
unixronin
LOMS Incident

One of the more drastic things that can happen in a nuclear power plant is what's known as a LOCA, a loss-of-coolant accident.  I like to refer analogously to some of the more drastic things that can happen to electronic equipment as a LOMS incident — Loss Of Magic Smoke.

This is particularly relevant today because that's what just happened to my main uninterruptible power supply, an APC SU3000RM3U which powers both of my workstations as well as my server/network rack.

As close as I can figure out, the capacitor just to the left of that power blade failed first.  (You can see another matching one about an inch behind its mortal remains.)  This was the first muffled bang I heard, and everything lost power at that exact moment, which is probably why nothing powered by the UPS was damaged when that row of power transistors went into runaway and blew up in a ripple about eight seconds later, creating a second, much louder and sharper bang.  Not only did they vaporize their power leads, they blew several holes in the top layer of the main board.  This was the point at which the magic smoke began to drift out from the front of the UPS.

The UPS, of course, is toast.  And it was only last year I managed to locate a matching expansion battery chassis for it...

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Current Location: Gilford, New Hampshire
Current Mood: annoyed annoyed
Current Music: VNV Nation :: FuturePerfect :: Airships (2002, 08:18)

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Comments
jhetley From: jhetley Date: March 4th, 2012 02:48 am (UTC) (Link)
Definite LOMS incident. Makes trouble-shooting easy . . .
docstrange From: docstrange Date: March 4th, 2012 03:32 am (UTC) (Link)
Hmm. Yeah, I'm another UPS reconditioner/parts scavenger. Mostly older Powerware true-online units (some so old they are labeled AT&T or Lucent). Never had one go up in magic smoke - their common fail mode seems to be to stop being able to charge batteries - which is frustrating because, well, one runs out and gets new batteries and all is well. Until the second extended power outage. My best find so far, though was a new in box Fortress 1400 rackmount with dead batteries that cost me the price of shipping only.
ithildae From: ithildae Date: March 4th, 2012 05:38 am (UTC) (Link)
Makes me kind of wonder what the capacitor was doing in that circuit. Did it get the overvoltage first, or did it fail and overvoltage the triacs? Either way, it sounds like it was impressive, from a distance. I remember talking about the "magic smoke" injectors at the chip foundry. To put the magic smoke in the silicon. It was fun until I realized that a couple of students in my lab actually believed me. I just couldn't do that to someone I was depending on for part of my grade.
cymrullewes From: cymrullewes Date: March 4th, 2012 06:13 am (UTC) (Link)
His dad created some of the ovens that HP uses to bake in the magic smoke. (well, to solder the chips on to the boards.)
ithildae From: ithildae Date: March 5th, 2012 08:46 pm (UTC) (Link)
That is a fun legacy to have. Unfortunately, writing software is a mayfly art. You do cool stuff, and now it is obsolete. I have heard a scientist defined as, an engineer with a job. Someone has to make the breakthroughs work. It is seldom high impact like that process. It is still fun to solve problems.
mr_spock From: mr_spock Date: March 5th, 2012 06:38 pm (UTC) (Link)
Sorry that it happened to you. Does keep things "interesting" though, doesn't it?
unixronin From: unixronin Date: March 5th, 2012 08:02 pm (UTC) (Link)
Well, the good news is that the 2-year extended warranty that I forgot I'd bought on it is covering a replacement unit. They're shipping it out today.
ithildae From: ithildae Date: March 5th, 2012 08:41 pm (UTC) (Link)
That is indeed very good news!
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