[Techtalk] what is bricking?

[agoats at compuserve.com]

As a safety feature to keep capacitors from blowing up  like a stick of 
dynamite, many have vents that blow out at the leads. Since the leads 
are at the bottom of the board, you may not ever see where the smoke 
came from. Most of these have a rubber stopper type bottom that the 
leads come out of. This is for "soft" capacitor failures and it's the 
more common method for failing.

On some of the larger electrolytic capacitors, you'll see a "cross" 
pattern on the top of the capacitor. IF the capacitor has a "hard" 
failure, this cross pattern tears open and the coiled up metal films and 
insulator ribbon come rolling out with a lot of force. These have a 
really  loud bang, like a gun shot; and the smell, smoke and mess is 
spectacular!

I had a sealed HVAC  (High Voltage AC) capacitor go in the more 
spectacular fashion on my air conditioner compressor outside my house. 
It sounded like a .38 or 9mm caliber pistol next to the house, blew the 
entire end off of the welded, sealed lid and spewed about 40 feet of 
metal films and insulator ribbon inside the housing, as well as denting 
the sides of the steel enclosure. Electrolyte compound gooey, sticky 
mess covering everything! I had to clean the contactors on the switches, 
one of which was glued shut from the electrolyte. Yuck! You have to 
wash  your hands well after handling the electrolyte as most of it is 
caustic.

The amount of bang and physical destruction depends on the capacitor 
value and voltage. This is where all the energy is; and the more energy, 
the greater the bang. A 100 microFarad 10V capacitor might make a 
phhfffft! sound while a 180,000 microFarad 10,000 Volt capacitor is a 
few sticks of dynamite.

Alvin

On 01/25/2012 07:43 PM, Little Girl wrote:
> Hey there,
>
> Magni Onsoien wrote:
>
>> I used to work at a university several years ago, and we had
>> computer labs with desktop PCs. We had about 150 PCs bought the
>> same summer, and after 12 months the capcitors on the motherboards
>> started popping. This mostly lead to random failures and errors,
>> before the PC finally wouldn't boot, with "error 7".
> This seems to be a common event, considering at least three of us
> have reported it in this thread alone. I wish I'd been there to hear
> our monitor give up the ghost years ago. My boys said the screen went
> black, they heard, "AH! AH! PUHHHH!" and black smoke went up. They
> unplugged it, and when I got home I opened it up. There was a large
> black scorch mark on the inside of the monitor casing, but the
> innards looked pristine. You could have convinced me I was looking at
> brand new hardware in there. I'll never understand it. (:
>