"Chuck Harris" wrote in
message ...
Richard Knoppow wrote:

I don't think I have ever found a bad OD; nor have I
ever found
a bad BB that wasn't of the oil filled variety.

-Chuck

Hi Richard,

My experience with BB's is primarily with Tektronix and HP
equipment from the very late 1940's to the early 1960's.
They both used the banded BB's, and they were all oil
filled.

After the oil filled BB's failed in droves, Sprague
changed
the BB's to a plastic dielectric, which is, I believe,
what
you have seen. There might have also been a difference
depending
on the WV rating of the capacitor. The oil caps were 600V
rated
as I recall.

I have never seen an oil filled BB, that had failed, that
wasn't
all fuzzy and goopy on the outside. The mineral oil
definitely
didn't just evaporate.

-Chuck

It seems to me I've also seen some BB's with oil on the
surface and maybe dripping. At some point I will have to see
what I can find in the library to try to date the change in
design.

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Richard Knoppow
Los Angeles, CA, USA