The PHILCO Phorum

So I finally got time to start working on the 42-380.

I was just going through the third I.F. transformer can and noticed that there are a couple small capacitors that appear in the schematics that do not exist in the actual can (part 34b and 34d, both 100pf caps).

I remember from the 42-1008 finding a similar lack of capacitors in the I.F. cans.

What gives?

If you mean (34B) and (34D), they are there - they are embedded in the material in the top of the assembly where the trimmer (34A) is located, and are not replaceable.

A number of Philco output IF transformers made between 1939-1942 are made that way.

I was afraid that would be the case.

Now I need to remove that can again and take some measurements.

Pooh.

What makes you think the embedded capacitors are bad? I'd leave the IF can alone unless you determine there is a problem within. If you have to replace 34 B,C,D, you can probably do so from the lugs under the chassis if there is not enough room in the can.

Those caps are often just an additional plate(s) in the adjustable mica trimmer. Not something that routinely fails or falls under the classification of "replace all caps".

I had originally gone in there to replace the rubber insulation on the input/output wires and the internal 47K resistor (34C) because it's value had drifted beyond tolerance.

I was just asking about those caps because I saw nothing in there but the coils and a resistor. I try to measure every component to evaluate whether or not they need to be replaced. Now I have learned more about them. Thanks, gents.