[R-390] Recapping question

[Tim Shoppa]

Cecil wrote:
> My experience has been a bit different in that I have
> found several occasions where leaky paper caps were the cause
> of poor performance and  after changing them ended up with a
> much more lively radio and sometimes 
> correction of weird problems noted during testing or rough
> alignment work.

I can fully agree that things seem to work better after going through
a radio, cleaning it up, replacing out of spec parts, putting in
pretty caps to replace the yucky ones, retubing as appropriate,
and realigning, but I cannot honestly say that parts replacement
did much because as long as I'm into the guts I usually do all the
above.

Certainly leaky coupling caps being replaced has been part of the
above!

The black beauties I pull out of 390A's are clearly leaky (as measured
with a 9V VOM, not some fancy-schmancy hi-volt leakage test set!) but
usually the radio works the same both before and after :-). If you look
where they come from, most are just bypasses on cathodes or filament
lines where even a few mA of leakage causes only the vaguest symptoms.

Tim.