A Can Cap. Explaination by Wiki

**Mechanic688** · 01-29-2012, 11:02 PM

I just stumbled across this and thought I'd throw it out there to help explain whats going on with the failed motherboards/power supplies and flatscreen monitors and TV's.
Evidently this has been a ongoing problem for quite some time. Motherboard blowouts like this usually take out other parts but the same failure in monitors can be limited to just replacing a few new caps. This is compliments of Wiki;

The capacitor plague[1] (also known as bad capacitors[2]) is a problem with a large number of premature failures of aluminium electrolytic capacitors with non solid or liquid electrolyte of certain brands especially from Taiwan manufacturers.[3] The first flawed capacitors were seen in 1999, but most of the affected capacitors failed in the early to mid 2000s. They failed in various electronics equipment, particularly motherboards, video cards, compact fluorescent lamp ballasts, LCD monitors, and power supplies of personal computers. News of the failures (usually after a few years of use) forced most manufacturers to repair the defects. The problem seems to be ongoing; faults were still being reported as of 2010.[4]

Here is a sample pic of some shorted out can caps. Some will just bulge the tops while others will vent out the liquid either from the top or bottom.

**irondale** · 01-30-2012, 04:31 AM

I found a nice bigscreen samsung lcd 2 weeks ago ,plugged it up wouldnt turn on. I could hear the relays clicking,various parts being energized, and see the red light on the power button. I opened it up looked around and found on the power supply board one bulging cap 2200uf 10v . I took it out replaced it with a better cap 2200uf 16v, it fired right up.

**IdahoScrapper** · 01-30-2012, 05:21 AM

I'd be too nervous to replace anything on a circuit board/power supply for fear of burning my house down.

Although insurance replacement value is 3 times what I paid for the house...

New shop!!

I kid, I kid.

**Dumpster-Dee** · 01-30-2012, 10:45 AM

I'd be more afraid of what happened to Hoss !! IF I WERE YOU I mean !! CAN"T happen to me ! No envy here, Sigmond !!

**Mechanic688** · 01-30-2012, 11:51 AM

I opened it up looked around and found on the power supply board one bulging cap 2200uf 10v . I took it out replaced it with a better cap 2200uf 16v, it fired right up.

Yes it is perfectly acceptable to go up in size of the voltage (from 10 to 16v) but also from the 2200 on up to 4800mfd. That last # is a number to gauge the filtering of the cap, larger # being better filtering. You look at the difference in price from a 10v cap to a 16v cap and it's a couple of cents but when the factory is looking at the difference, it's .02 times 20,000 units = $400. savings on just one part. Now if you do that for a third of the parts inside the tv then you've saved enough to pay the bosses bonus for the year. It's all about saving money to the company,,,

**Otto** · 01-30-2012, 01:02 PM

"Yes it is perfectly acceptable to go up in size of the voltage (from 10 to 16v) but also from the 2200 on up to 4800mfd. That last # is a number to gauge the filtering of the cap, larger # being better filtering."

While it may be OK to increase the voltage rating on the capacitor, changing the capacitance (how many farads) will change the impedance of the circuit and thus how it performs. The designer of the circuit selected the capacitance, along with the values of other components, to have the circuit perform certain functions with input frequencies. A filter circuit in a DC power supply, for example, would filter out AC ripple. In an audio amplifier circuit, a range of frequencies would be blocked or passed - changing the capacitance here would shift the frequency range upon which it is meant to act on.