It's quite common in electronics. Either something goes wrong due to failure, or you make a hash of something on the bench and you are rewarded with fizzing and popping and the delicate smell of electrical smoke.
I've fried a few components in my time...blown the lids off a few IC's...shorted out the odd regulator...burned out tracks on a circuit board. I think about the worst thing for me was completely corpseing a cheap Chinese inverter and a fairly pricey power meter in the same session. £50 worth, tops.
Today I witnessed the 'release of the smoke-fairy' in full effect. The new job, see? I'm 'babysitting' a hospital in Carmarthenshire. I am temporary stand-in for the regular Engineering Technician who's been forced to take some leave - a case of use it or lose it.
So, there was me planning on several cups of coffee, changing a lightbulb here and there and helping out with some general reshuffling of a couple of offices. That and man the phone and pager waiting to attend to any engineering issues.
My first call of the day was the Operations Manager to say someone had yanked his phone cable out of the wall and broken the plug off the end. Fairly mundane for a man of my calibre. I swapped out his cable with one from a new phone, I can crimp on a new plug, and then swap the cables over again. Happy bunnies all round.
My second call of the day? A strange 'burning smell' coming from the MRI machine electronics rack. Yes, there was a bit of a whiff but to me it didn't smell of 'electricals'. More of a plastic, acrid sort of smell. Well, I wasn't sure what was up, but opened up all the racks and gave everything a good sniff. Nothing but the smell of warm electronics - a perfectly normal smell to my nose. We all decided it was a bit rank, but not as bad as when they called me, and I figured I'd just need to keep an eye on things and see how it went. My gut feeling was nothing untoward, and the smell was probably coming from the air-con unit.
Well, in a way it was the air-con to blame.
Half an hour later after restarting the machine, the pager went again. There was most definitely a smell going on, and not a good one at that. Slightly baffled, I re-sniffed all the racks, shrugged my shoulders, and scratched my head. Now, the reception area just outside the MRI suite was starting to smell, and my nose was finally connecting with my brain and telling me the smell was burning nylon, or at least a nylon-related plastic. Hard to tell with the aircon circulating chilled air, so I turned the aircon off for a few minutes. With no airflow, I then heard the sizzling sounds and smelled the smoke coming from an electronics module up near the ceiling space above the rack.
Not good! I dumped the main power and then ran up the aircon again to try and get rid of the acrid smell. Well, that sorted, the MRI pilot then called the emergency hotline for their engineers and organised a call-out. Obviously being a very expensive and very important bit of medical diagnostic equipment (and way over my technical level) having a specialist on call is an essential need.
Ok...shout me when there's any news, I told the MRI tech.
A few minutes later, I am patrolling the beat and call in to see if there is any update on the engineer. She's on the phone to him at that point, and nodding and "uh-huh"-ing and "yes"-ing and "no"-ing so I wait for her to finish.
Yes, it's possibly the vacuum pump. Could be a power supply? Might be a cooling fan? He's on his way and shouldn't be long. In the meantime, can I possibly put the power back on again as, without the helium and cryogenics operating, the magnetic core of the beast might overheat somewhat catastrophically and very expensively.
Oops! Oh well...power restored to the chillers and disaster averted. So long as the machine proper isn't started up at the control console, then the offending 'fried part' won't be powered and continue to fry.
Live and learn, I say. Only, when I called in later, I was told the engineer had been...yes it was the vacuum pump and/or associated gubbins and yes, something had burned out. Some thing that isn't actually 'used' by the staff, but just happens to be sat there churning away to itself. The engineer had 'unplugged it' and the machine was back up and running again, minus the damaged but unused part. He'll be back out in two weeks to replace it. The unused part...that they don't use. Got me.
Anyway, after that, a loose toilet door handle and a flickering lightbulb were mere trifles!
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