[sdiy] electrolytic cap degradation over time ?

[Fredrik Carlqvist]

Yes, the 105degree cap will probably last longer. The
expected lifetime of a electrolytic doubles for every 10
degrees cooler they run. So a 105 degree cap will have a
factor four advantage over the 85 degree cap. 

However, this is when they are used in an application where
they run hot. The output caps probably don't run at 85
degrees, so you can use any (high quality) caps. But the 105
degree type is perhaps better sealed, so it could have a
better life expectancy for your application too. 

It is not the heat that kills these decoupling caps, it is
time. There is no way around replacing (wet) electrolytic
caps every 15-25 years or so. The failed one in your
CD-player is probably a low-quality cap to start with and
not the best one in its batch.

Fredrik C


-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of
Peter Blackett
Sent: den 29 februari 2004 19:27
To: synth Diy list
Subject: [sdiy] electrolytic cap degradation over time ?

Hi,
a question for those knowledgeable people on this list .
I've been looking at an Arcam cd player about ten years old
.
the problems with it are that one output channel is low in
volume and lacks bass .
so I opened up the case and found after looking at the
circuitry that one of the  electrolytic caps in one output
channel has lost value .
( it measures about 10% of what it should do ).
I know that its a problem with degradation over time , but
are there any pointers that I should look at for replacement
caps ?
are 105degree rated caps likely to last longer than the 85
degreee rated caps ?
I'm assuming this is why a lot of caps are needing changing
in synths and their power supplies .
regards Peter