"Richard Knoppow" wrote in message
ink.net...

[snip]

I am aware of he problem with the Sangamo "Black Beauty"
caps. they were all replaced with disc ceramics in my JX-17
but only in the RF deck of the JX-21, or perhaps its a
JX-26. I've replace a number of them that were obviously bad
but there nearly 60 in the receiver and not all are bad.
BTW, these ubicutous caps were originaly marketed by Sangamo
as deluxe quality replacements for wax dipped paper caps.
They are paper impregnated with Mylar in molded resin cases.
I suspect the problem is that the casing is not stable and,
as it drys out, disturbs the connection of the capacitor to
the leads and also lets moisture in causing very high
leakage.

[snip]

If your capacitors are anything like the oil-filled Sprague Black Beauties,
I'd replace all of them on sight. It might just be my bad luck, but the
oil-filled Black Beauties seem to short even harder than the wax paper caps.
However, if the later paper-mylar Black Beauties are like the early series
of paper-mylar Orange Drops, they should hold up well.

I think the all the oil-filled Black Beauties had one of the wires soldered
into a ferrule and the paper-mylar Black Beauties had both of the leads come
out in the standard way.

The paper-mylar Black Beauties seem much less common than the older oil
filled Black Beauties. As far as I know, paper-mylar was around only in the
late 50s to the late 60s.

Frank Dresser