[Nick3092]

I did some more tracing and injecting AF, and It just seemed like the issue was somewhere between the RF and audio sections. Which pretty means the volume pot.


 I noticed that changing tone controls never seemed to affect what little volume I was pulling out to the speaker. So I checked that section. Seemed ok. Then I disconnected the tone circuit from the pot, no change. Then I disconnected the whole pot. I grabbed a spare pot I had laying around (modern one form a different project) and put it in circuit with alligator clips. Worked perfect.

So I clearly have something going on with the volume pot. Which is sort of odd, since it seemed to be ohming out correctly while it was in the radio. And it appeared to work correctly at the seller's house. I'm hoping this can just be cleaned somehow, as this pot is made of unobtanium. It has a slot cut in the shaft for an extended rod to fit in, plus its a 4 tap.

I took it out, and disassembled the pot. Here is what I found:
   

While disassembled, I checked the terminals with my DMM. From outer to outer I get 2.15M, which is right per the schematic. From the "top" leg where the signal comes in to the tone leg, 1.6M. From the ground leg to the tone leg it's 1.1M. So that seems to be correct. From the wiper leg, I have no continuity to any other leg, and have continuity to the brass ring. You can see tracks in the black (carbon?) material from where the wiper made contact. I'm really hoping just cleaning this up will fix it, as it seems to be ohming out correctly.


So, is this fixable/cleanable? And if so, what is the best way (I know I'm opening up a can of worms as everyone has a preferred method and I could get 30 different answers)? I have Dexot D5 and F100 at my disposal. Probably some CRC QD cleaner laying around somewhere. And both 70% and 91% isopropyl alcohol. I'm assuming D5 could be used on a Q tip in the metal pieces. But what is the best way to clean the resistance track?