[sdiy] Dead capacitors

[Oren Leavitt]

On 5/11/2011 7:57 AM, Harry Bissell wrote:
>
> Dead polystyrene caps are not common... but
>
> They can be damaged by some chemicals (be careful of what you clean the PCBs with)
>
> They can get broken leads from vibration especially with the radial lead parts
>
> They can be damaged easily by soldering, Their ability to withstand heat is very limited !
>
> H^) harry
>


I see polystyrene caps develop cracks, even exposing the foil, as they 
age too.

- Oren


> ----- Original Message -----
> From: dan snazelle<subjectivity at hotmail.com>
> To: Synth-Diy diy<synth-diy at dropmix.xs4all.nl>
> Sent: Wed, 11 May 2011 08:38:07 -0400 (EDT)
> 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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