Brads Electronic Projects Forum

Capacitor plague

Capacitors dry out

http://en.wikipedia.org/wiki/Capacitor_plague

This was specifically about capacitors made with the electrolyte formula copied incompletely. In our aircraft products where we've used millions of capacitors starting 22 years ago, the only failures have been that one particular value of electrolytic capacitor, 220uF/16V in a 6x11mm case, with 6V on it in use (meaning it's operating at only 37% of WVDC) short internally, with no leakage or bulging; and the other is that on rare occasion a monolythic ceramic capacitor would have an infant-mortality failure as an open circuit. None of our other electrolytics have failed at all. We've had relays fail, but those were infant mortalities too; and if they made it through the first six months, you could be pretty sure they'll last indefinitely. I have plenty of electronics from the 1970's with electrolytic capacitors, and none of them have failed.

One of my work colleagues used to repair Apple computers in the 1980's and he said that the capacitors in the power supply had a DCWV of less than what was actually across them. Therefor they failed pre-maturely.

I found that when I worked at TEAC in the early 80's also. For example, to save space money, they'd put a 25V capacitor in a 25V power supply application where they needed a few thousand uF, and they'd go out sometimes. The smaller ones in the audio circuits never went out though, as those were rated for far more voltage than they got in the circuit.

I could have mentioned this before, but I have picked up a few LCD televisions from the tip and some had faulty capacitors in the power supply. I replaced them and they worked again! We are very much a throw away society aren't we.