The exploding capacitor.

**armygreywolf** · 03-14-2016, 02:42 AM

I think this deserves posting since it has happened twice in as many days.

Yesterday I was testing a 1000W power supply that by all appearances seemed in good order. It passed the voltage and load tests too. Was going to use this one for a build, installed it, set everything up, powered up...two minutes later the big cap (the pre PWM 12+ bus cap) exploded. Not...popped, exploded loud enough to be about as loud as a 9mm going off. Haven't had a heart stopper like that in a long time. But it does go to show you...don't leave untested stuff unattended.

Then today happened. I should have known this...really...but it is MUCH more difficult to tell if a cap is bad on an ASUS board with solid caps than any other kind of motherboard. Especially when the board itself is black and you cant see the electrolyte leaking onto the board. Testing boards from a large lot and this board blew the cap at full bus amperage to the point it looked like a welding arc. The short to ground protection circuit in my test PSU tripped and cut the power to the board after a second or two but again... with a 400W 12+ bus 100% duty it's entirely possible I just watched 60 to 80 amps arc across a motherboard. Sure smelled like it.

Anyone else make electronics go boom lately?

**jimicrk** · 03-14-2016, 05:39 AM

Not lately, but about 20 years ago we received a shipment of NEC power supplies for some phone systems we were installing.

About 20 seconds after powering them on it sounded like a gun going off. It turned out to be a bad lot from the factory.

**Ewasted** · 03-14-2016, 08:05 AM

Ouch!
We had a hard drive catch on fire!

**armygreywolf** · 03-14-2016, 02:17 PM

Holy cow a hard drive! The last thing I'd ever expect to set fire. I have had ram chips MELT during the memtest operation, board wigs out but never shuts off and the memory just gets hotter and hotter until I smell it.

**mikeinreco** · 03-14-2016, 02:35 PM

Had a flat screen start smoking...it required external power supply and I had the universal set to Wrong voltage....made for that nice smell of burning platic

**armygreywolf** · 03-14-2016, 03:05 PM

Normally I break mechanical things not electronics...been pretty good about that. I break my truck somehow once every other month (lots of miles though) but the gunshot sound from the cap was startling, especially at the late hour. I had gone into grind phase just trying to get it done and go home.

**mthomasdev** · 03-14-2016, 03:23 PM

Originally Posted by armygreywolf

Normally I break mechanical things not electronics...been pretty good about that. I break my truck somehow once every other month (lots of miles though) but the gunshot sound from the cap was startling, especially at the late hour. I had gone into grind phase just trying to get it done and go home.

Was that one of mine?

**ryanw** · 03-14-2016, 04:40 PM

I've had several IDE hard drives get very hot very fast after powering up...enough to have caught fire if I didn't notice it.

**Scrappah** · 03-14-2016, 05:38 PM

Two things in two days ... might just be an odd coincidence.

All the same ... you might want to check your electricals. The building ground wire ought to be renewed every seven to ten years.

(Nowadays, some are even going to using two ground rods spaced well apart on the higher end jobs.)

Any chance the power company lost the ground out on the pole ? Any tree branches rubbing up against the service entrance when the wind blows ? Any chance the transformer out on the pole is getting old ?

**armygreywolf** · 03-14-2016, 05:58 PM

All my electrical is monitored through an Eaton system. I beat the earth ground in myself last October, but it's **** good advice for the rest of the forum members.

MThomas- No, but I've had a few shut off and not power back on during testing. Yesterday two of 8, still **** good results, I'll be done Thursday for sure. Second to last run tomorrow.

**Ewasted** · 03-15-2016, 07:14 AM

The hard drive that caught fire was a FLAME! We are fortunate that we didn't leave these running over night. Be careful!

**RLS0812** · 03-15-2016, 10:00 AM

Most excitement I ever had in the last year was catching a stepper motor on fire, and popping a couple caps at work.

A few years ago I seen the aftermath of a transformer fire, but missed the 'show'