[Milsurplus] Micamold Recovery
David Stinson
arc5 at ix.netcom.com
Wed Jun 4 12:12:10 EDT 2014
I recently acquired a lot of NOS, unused "Micamold"-like
capacitors with varying values- most around .01 uFd
at 250-600 Volts.
Most are the square and rectangular Micamolds
with some Cornell and Sprague in the mix.
I randomly selected 50 for testing. 21 of the lot displayed
varying amounts of leakage current and were set aside.
Two tested "open" and were discarded.
I subjected 7 of the "tested good" caps to 250 VDC
for 12 hours. None developed leakage. They and
the remaining "good" ones went into my parts stock.
I placed the remaining 21 "leaky" caps in a disposable
pie pan and put them in a 300-degree electric oven
for 1.5 hours, then turned the oven off and let them
cool undisturbed for two hours.
The larger rectangular caps leaked some oil.
A couple of the square caps had a slight "bulge"
in the center from (I assume) gas or steam pressure.
After cleaning them with a disposable towel,
I retested the capacitors and all save *one* now
tests "good." No leakage and all but three are within
"earshot" of their marked value.
The three test a bit low (i.e a .01 that tests .006)
but still "good" as-in no leakage at that value.
Have three of these caps sitting at 500V and
three of them at 250 V and will keep them there
for 12 hours to see if they start leaking again.
If they hold-up, I'd like to coat them with something
to keep the water out for another 70 years.
A friend suggested boiling them in clean beeswax,
which sounds messy, LOL.
Thoughts?
73 DE Dave AB5S
More information about the Milsurplus
mailing list