I Don't Know Where The Big "BOOM" Came From!!!

[Chris56000]

Hi!

I did an 18 month spell at a T & M Calibration/Repair house a few years ago, it wasn't a gratifying experience for me because of a personal dislike of me on the part of my immediate supervisor there, and also got a totally unjust accusation of deliberately damaging equipment!

(Surely I can't be as bad at that former employer made out?  I've had almost a lifetime doing everything from Radio & TV, to pc gear, T & M and industrials! If I do have a fault, it's getting engrossed in something far too deeply out of a desire to complete a repair and spending far more time than is cost–effective!)


On a more light–hearted related note, I'd like to start this topic with all what my Brother–In–Law calls "Piff–Paff–Puff!!!" –  tell us all about the worst accidental T & M equipment howlers that produced the most smoke, the biggest heartaches to repair, the most expensive "fuses" (things that  blow to protect the actual glass fuse!) and disaster–tales that happen just when you think you've got it all working!

Chris Williams

[mzzj]

230 VAC to 0-1v input on some industrial measurement  card. Both had same connectors so they got swapped at some point.

Pretty much every IC on the card blew up, 5 meters of circuit traces vaporized and dozen of tantalum caps explode in fires and throw burning pieces of tantalum around.
Multiple secondary fires around workbench from burning tantalum chips 

Tantalum cap pieces burn real hot!

[CJay]

Dunno, it breaks my heart every time I blow one of the 11A or 440mA fuses in my meters because it's such a dumb thing to do..

The OhNoSecond, the period of time taken to realise you forgot to move the meter leads from the amps socket to the volts socket on a multimeter when trying to measure the voltage across a source capable of sourcing enough current to blast the arse out of the fuse in the meter and is always longer than the rupture time of the fuse.

[Berni]

I haven't had any major catastrophic smoke generators so far.

One i remember was when i was fixing a 4 channel HP rack mount PSU. One of its channels was dead so troubleshooted it for a while, found a useful test mode, poked my scope around and found a faulty quad opamp chip. I get the thing sucked out and replaced with a DIP socket, but after going trough my boxes of parts i couldn't find a opamp that had the right combination of specs to replace it. I really wanted to know of this is the only thing that was wrong so i looked for some more and found that i have some SOIC dual opamps that have the specs i need so i dead bug soldered a adapter that turns two of those into one DIP quad opamp. So i plug it into the socket and turn on the power supply, reaching for the buttons to go trough the menus and suddenly there was a pop and smoke coming out of it. I quickly turn it off and check where the smoke came out. It turned out it came from those dead bug wired opamps... upon closer inspection i plugged it into the socket the wrong way around.

At that point i had enough and just went to order the correct replacement opamp from LT. Once it got here i stuck it into the socket (Paying a lot more attention to where pin 1 is this time around), i power up the PSU...no smoke this time, but the channel was still dead. More troubleshooting later i had no idea what was going wrong, it was having a different kind of fault, for a moment i thought i also blew up the DAC. Eventually i traced it down to a via being open circuit next to that opamp. Looks like the fault current from my backwards connected opamp blew it up. Fixed the via and suddenly the PSU works again.

[GreyWoolfe]

Some years ago, someone gave me 2 tube scopes that someone gave him.  Mind you, I didn't have a variac or dim bulb tester, now I have both.  I just plugged the first one in and there was a trace.  I plugged the second scope in and nothing.  Noting that the plug in modules were the same model numbers in both scopes, I decided to swap them in one at a time into the working scope.  The first scope was a rack mounted model, can't remember any details, without the covers on it.  The first module went in and the scope came to a trace.  When I plugged in the second module, there was a couple of loud pops and a 3 inch flame rose up out of the scope.  I quickly unplugged the scope, however, the smell of what ever blew up lingered, actually for quite a few hours.  Unfortunately, the smell was still strong when SWMBO came home from work.  She was madder than a wet cat and made me put both scopes out on the curb.  Yes I am whipped but for a very good reason that I won't get into!  

[Chris56000]

Hi!

Keep the tales coming ladies and gents – they're .asking me feel a bit better already!

Any Chain–Reaction Tales of tales of multitudes of surface–mount sparklers, anyone?!

Chris Williams

[Fungus]

What's the most expensive piece of gear anybody's destroyed when a moment's thought could have avoided it?

[hansibull]

First day at new job, destroyed the graphics driver on a brand new LeCroy Quantum Data 780. It still works but the colors are all messed up.
In order to replace the battery you'll have to remove the LCD panel, which was just a standard 2mm pitch header connector with no keying. An offset by one really did the trick!

[bob225]

Never smoked a piece of test gear, But i did get thrown 4ft backwards and killed £2500 worth of Sony CRT, The smell of burning skin/hair, pcb and dead caps filled the air

It took a week to get rid of the smell out of workshop

[KD4PBS]

Not me personally, and not test equipment, but I have in a former life had to repair many pieces of expensive high-end broadcast equipment over the years, typically always due to a TV news videographer who thought he would get the next Edward R. Murrow award.  It always went one of a few ways:
1) Hurricane or some other extreme weather phenomenon that happens frequently, news photog feels it is best to shoot video right in the middle of the storm instead of from a protected site (typically inside the live truck or the door to the hotel), waterlogging the camera, and doesn't even bother removing the easily-removable battery.  $12,000 USD and 40 hours' labor later, the camera is working.
2) The news photog feels it's best to not bother bringing the camera back to the shop for the engineer to fix those 99-cent loose handle screws on the camera, so he uses a $1.99 toenail clipper to do it every now and again.  As a result, handle separates from camera and ends up dropping into salt water. Doesn't even bother removing the easily-removable battery.  $30,000 later for a new camera, lens, and VCR deck, and all is well.
3) The news photog is an ace.  So much so, he knows how to set the backfocus without a backfocus chart.  While camera is on his shoulder.  Walking backwards.  Down a flight of stairs.  In doing so, he ends up turning the lens locking cam instead, and the whole camera and deck slides from his shoulder and tumbles 12 flights of steps down the stairwell.  At least he still has the lens in his hand.  $15,000 later for almost everything new in and on the camera and VCR, and 120 hours' labor to repair, and all is well.
4) The news photog walks away from the camera while it's still on the tripod.  In doing so, he trips over the camera power cord, causing the whole assembly to fall square on the lens.  Lies about it all stating that the camera "just fell for no reason".  Thankfully one of the competitors showed the video proof to his engineer, who showed the video proof to me, who shows the video proof to the news director and general manager.  New lens, chassis, and optical prism block and assembly later, along with the 40 hours' labor and $10,000 parts cost, and all is well.
What's worse is that none of them ever got called to the table for these kinds of shenanigans.

Take my word of advice; no news is good news.

[ralphrmartin]

I blew up an oscilloscope in my A-level physics practical exam. I still got grade S1 in the special paper.

Still not as good though as when the physics teacher put a 6V battery directly across a galvanometer. 

The chemistry teachers were the ones out to impress though. They always had a competition on Nov 5th, but I still remember an impressive demo of melting a screwdriver by lying it across the terminals of a car battery...

( I'm more careful now its my own personal oscilloscope.).

[Neomys Sapiens]

Most spectacular demise of a multimeter that I witnessed happened when I was working with traffic signals dept. a long time ago. In a circuit where some low voltage was expected, a swapped connection + a inter-departmental CF resulted in 750V DC streetcar power coming through. If I remember correctly, it was a H&B, but that is a bit hazy. It flashed within such that it shone somehow through the instrument.
Inside, it was a black mess.

Some years ago, I bought a huge sturdy 4-channel paper recorder. Japanese maker, but I have no record which. When going through the initial testing, the transformer blew. It started with a sizzling noise, then a lot of smoke came out. My flat stank for days.

Small Voltcraft experimenters power supply which a friend brought in for test/repair. I was just starting to probe when the main cap blew. I stood in the rain of corrosive fluff while the aluminium cup, which flew away completely, settled noisyly in some corner after it's zigzag journey through the lab. 

[coromonadalix]

while charging an ni cad battery, it overheated, exploded, and left an awful black powder 5 feets around it ( like photocopier ink) was very hard to remove, incrusted ... the first day at my new work  loll

the second one in old crt tv's,  an 34 inch tube tv, while discharging the tube with an screwdriver connected to ground, my hand had some transpiration,  it made an beautiful ark and a small burned hole in my hand while reaching to the ground ... 

oh almost forgot that one, an friend asked me to check with him a noise coming from a tv,  while i was approaching the tv  capacitors blown aways up to the roof, my friend and i  where lucky, the capacitors passed near my face an his face and lodged into the roof sound isolation tiles, the tv totally died, almost every ic's and transistors blew away.

[Cerebus]

...TV news videographer...news photog...news photog...news photog...news photog...

Ah, cameramen, ya gotta love 'em. When they're not breaking things they're lining up shots of tits and bums until they the producer shouts at them and gets them back on shot... 

[Neomys Sapiens]

...TV news videographer...news photog...news photog...news photog...news photog...

Ah, cameramen, ya gotta love 'em. When they're not breaking things they're lining up shots of tits and bums until they the producer shouts at them and gets them back on shot... 

Someone has to do documentaries about those small, often overlooked birds and the plight of the homeless!

[ralphrmartin]

OK, not test equipment, but I remember many years ago, a friend of my dad's decided he would make himself a variable speed control for his windscreen wipers when such things were very new.

He built and installed his circuit, and when he turned it on, the two TO-3 transistors couldn't handle the wiper motor starter current. They both blew, and he ended up with two neat round dents in his car bonnet...

[CopperCone]

i was probing a broken 30v 30a lambda/xantrax supply and i accidentally bridged a linear regulator, it made a rough noise and blew a fuse.. probably took out half the control board too

[SeanB]

I saw a Fluke 77 that was Metro electrical issue, returned under "warranty" as it was defective. Probes on this less than a year old meter were best described as ' mostly there, at least the parts near the meter side", as they basically were just burnt wires plugged into the sockets of the meter. Watched as the agents opened the meter, and saw that Fluke had done some interesting shielding inside the case, as it was entirely bright copper coated. PCB had a full complement of parts on it, rotary switch was stuck in voltage measurement, and the LCD came on with random segments on plugging a 9V battery in.  However the entire meter from the bottom of the LCD down had not a single copper trace there, all blown clean away, leaving just soldered component pads and bare board with no solder resist where the traces had run. both fuses however were still intact, tested with another meter.

Turns out somebody had tried to test the PRIMARY side of a MV distribution transformer, and that, for some reason, the meter did not really like having, as Dave so eloquently says, having 11kV, at a source impedance of practically Bugger All, shoved up it's clacker. No word as to if the primary fuses or the substation trips operated, or if they were ever able to remove the remains of the probe tips from the bolts either. Hopefully no Darwin award either.

[SaabFAN]

Most expensive to date: PM3323.

I apparently managed to damage one of the P2CCD-Chips when I tried to repair it (see my PM3323-Thread for more details). The result is an unrepairable scope that is taking up space here while I'm figuring out if I should try to emulate the function of the P2CCD Chip that is unobtainable, has no datasheet anywhere on the net, and is an SMD-component (rather hard to make a interface between a replacement built on a PCB and the old footprint).

About 150€ worth of magic smoke in this case. And the lesson to stay away from nasty ceramic chips that are prone to breaking

Btw. anyone here who want's the scope for parts? 

[najrao]

This happened in our testing shop, which has a 400V 3phase 1500kVA feed. Noticing an iron crowbar(?) sitting on a ledge about a foot  above live oil circuit breaker terminals, I admonished the test engineer for such recklessness, and told him to take a shutdown to remove the offending metal bar. Minutes later, there was a huge explosion, and a creature emerged on all fours, covered in black soot all over. He had tried to remove the crowbar, and promptly dropped it on the M36 copper stud terminals. His injuries needed 6 months of intensive care, and left him scarred for life.

[Zucca]

I got yesterday some holy smokes events playing with Li ion cells. I did not damage the cells  .

Li ion cells are scary, if you do a mistake on building the battery pack, there is no way to turn them off... you have to watch them smoke and die until the energy is dissipated.

[PaulAm]

Along that line...

In the US utilities use an electrical meter that plugs into a socket.  The line (supply) terminals are the top 2, the load (house) are the bottom 2.  I was building a house and before the utilities put in the meter one of the contractors sent out an HVAC tech to do a trial run on the heating plant.  Well, he needs power for that, so he goes to install shorting bars on the meter socket - HORIZONTALLY.   (he's using one of those sliding metal fasteners they use to clinch ductwork together and when you bend tabs on it, that's the only way it will fit, right?)  The first one across the bottom is fine, the second vaporizes instantly with a loud bang and flash.

The tech survived with no injuries, but left soon after without doing his test.

[schmitt trigger]

Anyone who has not witnessed a large, shunt-field DC motor lose its field and spool up until self destruction, has *not yet seen* a catastrophic failure.

On a shop I worked many years ago, we assembled large industrial controls...all low voltage <600 V, but large power.

We were delivering a 100 HP motor and its controller, and were in the final testing stages, and everything was metered up.

One of the critical tests was to ensure that the field loss detection circuit was indeed functional, where one deliberately removes the field excitation. Mind you, this test is done with the armature fully disconnected. You remove the field, and listen for the main contactor releasing.

So....this technician decided to cut the field wire. With the motor running at full armature voltage. Unfortunately for him and everyone else, the motor was sitting right next to the control panel where the red emergency stop button was located. You don't want to be near a large motor self destructing by the centrifugal forces.
Someone had to run to the building's main breaker panel, to shut off the main breaker.

Of course, this large motor was ruined. So were several pieces of equipment, including our brand new Tek scope which had been hit by shrapnel.

[Berni]

Now that motor mishap must have been quite the scene. What gets torn off it anyway? I would think that most of the rotor chunks would get caught by the stator around it so its things like the cooling fan exploding from the forces?

[schmitt trigger]

Yes, the cooling fan starts disintegrating first.
The brushes and commutator suffer also significant damage

So far, things can be repaired.....but when the unbalanced rotor spinning at a freaking speed hits the field poles, then the thing is damaged for good.