[vcf-midatlantic] Reforming capacitors

William Sudbrink wh.sudbrink at gmail.com
Sat Dec 7 18:31:16 EST 2019

I've just "brought back" two Sols.  I did not find either power supply in
need of capacitor reforming.  I brought each power supply up on a variac,
powering a dummy load (multiple 1 ohm, 10 watt, resistors).  I brought up
the variac over the course of an hour, checking each stage of the supply.
All smooth as glass.  I then let the supply drive the dummy load for a day,
checking regularly.  No problems.  The only issue was that all of the
unregulated S-100 supplies were out of spec.  This turns out to be a design
issue, with a specific engineering note to address it (adding a bucking
transformer) which I applied.

Hope this helps,
Bill S.

-----Original Message-----
From: vcf-midatlantic [mailto:vcf-midatlantic-bounces at lists.vcfed.org] On
Behalf Of Mike Loewen via vcf-midatlantic
Sent: Saturday, December 07, 2019 12:12 AM
To: vcf-midatlantic at lists.vcfed.org
Cc: Mike Loewen
Subject: [vcf-midatlantic] Reforming capacitors

    Before I reform the large electrolytics in my Sol 20, I'd like to poll
collective as to the recommended procedure. I have a constant
current DC supply, so I can set voltage and current limits. For those of you

who have done this, what's your procedure?

    For a constant voltage/constant current supply, do you need a resistor
series with the cap? If so, typical value?

    What's the recommended max current during the reforming process? I've
recommendations of 50ma and 100ma.

    What percentage of the working voltage do you initially take it to? How 
much do you raise it after the current drops? How long do you let it sit at 
each stage?

    I'm interested in hearing from folks who have actually done this, with a

constant voltage/constant current supply. Thanks for your input!

Mike Loewen				mloewen at cpumagic.scol.pa.us
Old Technology				http://q7.neurotica.com/Oldtech/

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