The PHILCO Phorum
Question about I.F. cans - Printable Version

+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: Question about I.F. cans (/showthread.php?tid=9864)


Question about I.F. cans - Eric T - 06-21-2014

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?

[Image: http://i145.photobucket.com/albums/r233/etjunk/3rdIFcan.jpg]

RE: Question about I.F. cans - Ron Ramirez - 06-21-2014

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.

RE: Question about I.F. cans - Eric T - 06-22-2014

I was afraid that would be the case.

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

Pooh.

RE: Question about I.F. cans - codefox1 - 06-26-2014

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.

RE: Question about I.F. cans - exray - 06-26-2014

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".

RE: Question about I.F. cans - Eric T - 06-28-2014

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.