[bridkarl]

I’m having to pull the IF cans to replace the wiring which is rubber and just totally gone.

While I have this apart is there some way to test for silver mica disease, maintenance on the cap, etc??? Anything I should/can do while this is disassembled?

[RodB]

I believe SMD (silver migration disease) doesn't occur until the late 1940s when the miniature slug-tuned IF cans started showing up. It's a risk to do too much other than replace the leads. About the only other thing to consider is cleaning the mica trimmers but only when past environment really affected operation, ie crud factor.

[bridkarl]

Good. I’ll just do the leads and call it done. Thanks.

[bridkarl]

Well I think I managed to mess up the wiring of the 1st IF to the 7B7. I kept the old leads attached to the socket, remounted the can, and soldered the new wires in the correct places I thought.

I kept the wiring colors the same when I rewired the IF can. The schematic isn’t clear but it appeared from the unit that the green wire went to pin 6 and the blue wire went to pin 5. I’m now wondering if I have that wire in the right place as there’s a stub of a blue wire on pin 3.  It’s clearly blue based on looking at the cut end of the wire.

 Perhaps the wire colors were faded and I’ve confused them? In any event I have a PT-4 on order which has the exact same chassis so it should be easy enough to compare them once it arrrives.  Not that I needed another project but why not?