[sdiy] Dead capacitors

[dan snazelle]

This week I spent a few days trying to repair a broken Tracer City. I was the second person who had tried to repair it.

After a about 10 hours of testing I finally found the culprit

the entire circuit was being taken down by a shorted Polystyrene 220pf capacitor!!!!

(It was in the feedback path of an integrator opamp, which happened to be the Low pass stage of a filter.....so it killed the rest of the filter
which meant that the sound of the entire box was no good)


What I am trying to figure out is 

1. are polystyrene caps prone to Failure? IF so, under what conditions?

2. Are DUD poly caps common?


I have never encountered this problem before.


thanks!






http://www.youtube.com/user/snazelle