[R-390] Finally!!!

[Scott Seickel]

> Hi,
>
> The yellow Aerovox capacitors have a plastic dielectric in them. They are
> more reliable than the paper dielectric black or brown capacitors. I have
> pulled a lot of the paper parts out of R-390's and have yet to find one
that
> is in good shape. I suspect that soak up humidity over time and that's the
> end of them.
>
> I have yet to see anybody come to the defense of the paper filled caps. I
> would replace them wholesale with plastic dielectric parts.
>
>     Take Care!
>
>         Bob Camp
>         KB8TQ



The Aerovox are more reliable but I knew there was reason to be
cautious about them also.    I searched the archive and found this
post from Nolan.   (This should make Joe happy, read post below).
The bottom line, I think, is that it is NOT unreasonable to just recap the
whole radio.
An ounce of prevention is worth a pound of cure.
Caps just have a high rate of failure no matter what they are made of.
 If you don't recap, you may have a failure that does damage to other
components
of your radio.  The very expensive and hard to get filters are just one item
 that can be ruined.

Scott

>>>>>>>>
Date:Tue,06 Oct 1998 02:31:38 -0500
From:Nolan Lee <nlee@gs.verio.net>
Subject:[R-390 ] R390A paper capacitors
I just removed all three of the paper/tubular capacitors from the RF deck of
the
EAC.This is a very low mileage "cherry"deck with the original tubes.Using a
loupe,I noticed that the "brown beauty of death"had a microscopic split
about a
half an inch long down one side just like most of the ones I'd looked at.I
threw it
on the RC bridge and couldn't get a solid value.It did slightly "dip"at
aboutഊCapacitor Replacement Tips page 13
0.033mf.I tried a leakage test.Almost a dead short above about 50 volts or
so.I
haven't found one of these style capacitors yet that was good.Maybe it's the
humidity here or just bad juju.
I tried the two yellow 0.1mf 200V Aerovox capacitors from under the crystal
oven.Only a slight "dip"of an indication of the value on either of them.One
leaked like hell at voltages about 30 volts and the other broke down totally
at
about 100 volts or so.Granted,one of them is only used help kill the static
from
the 6.3V oven cycling on and off and would have probably continued to work
for decades to come,it was bad.I've been testing all of the caps that I've
been
replacing.Maybe 10 to 20 percent of the hermetically sealed Vitamin Q style
ones
won't meet spec.None of the "brown beauties of death"will even come close
and about a third to half of the yellow Aerovox ones are bad.
A lot of people questioned my replacing of all of the capacitors.I'll stand
by my
decision.These tests have reinforced my opinion that if you remove a module
from an R390A,to work on it,replace all of the original paper caps in it
before
putting it pack in the radio .If you don't want to replace them all,at least
make
sure that you replace the brown tubular ones.Only a couple of three dollars
and
you've eliminated a possible cause of flat out failure that could cause
damage to
something expensive and a pain in the ass to change or at the
least,decreased
performance.