16 Mar
2005
16 Mar
'05
3:46 p.m.
John Lawson wrote:
So the moral of the story is to bring a
long-dormant power supply up
slowly, using a variac and loads, and to be vigilant for any signs of cap
leakage, swelling, getting suddenly warm, or hissing sounds coming from
one.
Only for linear supplies! Don't do that with switchers.
It's probably worthwhile to disconnect electrolytic capacitors and
reform them separately first. There are tons of web pages about that,
but the basic principle is to apply current-limited DC to it and slowly
let it charge. If you apply rated voltage without current limiting,
and it needs reformation, that's likely to cause it to fail
catastrophically as John described.
For a very overengineered approach to capacitor reformation which we
used on the PDP-1 project, see the draft of the restoration procedure,
the fifth document in this directory:
http://pdp-1.org/Documents/RestorationProject/
For software that automates that procedure using an HP or Agilent
programmable power supply, see:
http://www.brouhaha.com/~eric/software/wrec/
Eric