Attributions unfortunately lost, but somebody out there asked:
> Has anyone got one online? If so, URLs please...
Actually I think I have _too_ many. :) I ended up having to read several
in order to come up with a good overall picture of what was happening. It
may be you don't need all of these, but here's a few of the websites
where I found useful information. Several of these seem to be concerned
with capacitors from antique radios and the like, with voltages up around
400V, but the information is still worth a look:
http://home.insightbb.com/~stephenwmoore/Electronics/Reform.htm
http://www.vcomp.co.uk/tech_tips/reform_caps/reform_caps.htm
http://www.vmars.org.uk/capacitor_reforming.htm
http://www.angelfire.com/electronic/funwithtubes/Restore_cap.html
http://www.nmr.mgh.harvard.edu/~reese/electrolytics/index.html
http://www.parse.com/~museum/pdp12/pdp12/restore1.html#20031114
If you want significantly more detail, or don't want it but later discover
you need it anyway, here's a Cornell-Dubilier PDF on electrolytic
construction and a _very_ detailed account from CWRU of what, exactly, is
happening during the capacitor construction and forming process:
http://www.cde.com/catalogs/AEappGUIDE.pdf
http://electrochem.cwru.edu/ed/encycl/art-c04-electr-cap.htm
...To comment on one reply, for which I also managed to lose the
attribution:
Amongst the serious electronics restoration and repair
folks I deal
with, reforming caps is pretty much a waste of time. The only
electrolytic caps that seem to really require careful handling are
those made prior to 1950 - the kinds that we never encounter.
Well, the PDP-12 I've been working on was surprisingly finicky and
unstable until I'd fully reformed the power-supply caps - turns out on the
first go I hadn't reformed them to their full capacity, and the -12 _knew_
it, and it didn't like it. :) So I think it's still a relevant skill,
even with equipment as late as c.1971.
(Knowing someone who accidentally _blew up_ a cap in a PDP-11 PSU by not
reforming them first is an added incentive, of course. <g>)
Think about it - of the zillions of powerups and
reformations some of
us have done, when has there been clear evidence that somehow all the
reformation processing has actually worked?
<raises hand> It's pretty easy to verify, actually. After doing the
reforming discharge the cap, then turn the reforming current back on
again. If reforming is taking place correctly, the voltage on the cap will
increase _much_ faster than it did during reforming.
-O.-