[sdiy] capping

[David G Dixon]

I've read all these recapping posts with interest, but I gotta say, I avoid
using electrolytic caps except for power rail decoupling purposes.  I never
design them into actual circuits (and I've never built my own power supply).
Same with tants.


  _____  

From: Synth-diy [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of
Chris Juried
Sent: Wednesday, February 03, 2016 8:39 AM
To: Steve Ridley; synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] capping


FYI, Excellent read by Douglas Self on Electrolytic capacitor
non-linearity... https://books.google.com/books?id=u249BAAAQBAJ
<https://books.google.com/books?id=u249BAAAQBAJ&pg=PA71&lpg=PA71&dq=self+dc-
blocking+electrolytic+distortion&source=bl&ots=zMONtIOWnJ&sig=IS2A60Ve9AWEFb
fbj_JsFYfUQXY&hl=en&sa=X&ved=0ahUKEwj8hr-6uNnKAhVDyWMKHT9aDcMQ6AEIMDAD#v=one
page&q=self%20dc-blocking%20electrolytic%20distortion&f=false>
&pg=PA71&lpg=PA71&dq=self+dc-blocking+electrolytic+distortion&source=bl&ots=
zMONtIOWnJ&sig=IS2A60Ve9AWEFbfbj_JsFYfUQXY&hl=en&sa=X&ved=0ahUKEwj8hr-6uNnKA
hVDyWMKHT9aDcMQ6AEIMDAD#v=onepage&q=self%20dc-blocking%20electrolytic%20dist
ortion&f=false 

 
Sincerely,   
  
Chris Juried  
Audio Engineering Society (AES) Member  
InfoComm-Recognized AV Technologist
http://www.JuriedEngineering.com <http://www.juriedengineering.com/>
(Juried Engineering, LLC.)
http://www.TubeEquipment.com <http://www.tubeequipment.com/>  (Tube
Equipment Corporation)
http://www.HistoryOfRecording.com <http://www.historyofrecording.com/>
(History of Recording)
http://www.linkedin.com/in/chrisjuried (LinkedIn)
Email: CJuried at yahoo.com  
Voice: (954) 478-4355 


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  _____  

From: Steve Ridley <spr at spridley.freeserve.co.uk>
To: synth-diy at dropmix.xs4all.nl 
Sent: Monday, February 1, 2016 5:54 PM
Subject: Re: [sdiy] capping



I can see why recapping causes such mixed opinions. On one side, it makes
sense if you know what you're doing overhauling or repairing for a customer,
but when it's done "because everyone says you should do it" and the
replacement caps are cheap ones with a worst case life of 1000 hours it's
can be unnecessary vandalism. Recapping has it's place, but should be done
when necessary, not as a random act of maintenance.

Not all caps deteriorate at the same rate. Type, make and position can make
a huge difference. A cap next to a hot power device is likely to deteriorate
much sooner than an identical cap elsewhere. Certain makes of cap have a
poor reputation, but knowing which ones comes with time and experience. One
bad cap doesn't mean they'll all be bad. I like to know what's going on
before I consider recapping.

Some ESR meters will test caps in circuit. I use a Dick Smith ESR meter, now
discontinued, but EVB and Anatek make very similar models. They will give a
useful indication of the state of a cap without removing it from the board,
although multiple caps in parallel or shorted caps will give a false good
reading. 

The other important tools are your eyes and nose - look for staining at the
end of the cap. Leaky caps have often have a distinctive acrid fishy smell -
a real giveaway. 



Steve



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