[sdiy] Dead capacitors

[Paul Perry]

Polystyrene caps are notorious for heat damage by careless soldering - the 
polystyrene has a relatively low melting point.
I have never seen a damaged one myself, but I never use them anyway. I used 
to see lots of warning abot this back in the 60s when ther ewere fewer 
alternatives.

paul perry Melbourne Australia
----- Original Message ----- 
From: "dan snazelle" <subjectivity at hotmail.com>
To: "Synth-Diy diy" <synth-diy at dropmix.xs4all.nl>
Sent: Wednesday, May 11, 2011 10:38 PM
Subject: [sdiy] Dead capacitors


> 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
>
>
>
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