In article ,
Fred wrote:
....
NO, the squelch control that goes bad is the actual mechanical pot, a
little bitty one with, thankfully a small wire harness attached that
solders into the front board.

Ah, I see, that one works perfectly here.

I think I have solved the problem. It was not a component problem.
Under one of the PC-boards they had soldered a grounding lug. To
prevent this from shorting things on the PC-board they had glued
a small piece of plastic on the PC-board. This glue had turned into
a brown, rather brittle, substance, covering part of the squelch circuitry,
and also the input to the IF-amplifier. After removing this I found out
two things. The voltage at the input to the TK-10420 IF-chip raised
from 1.5V to 2V (which is the voltage supposed to be there), the output
from the chip rose from 2 to 3V (supposed to be 3.5V), and the S-meter
started to show signal strength again, something it have not done
for years... The squelch also started function again!

Using the test leads on my multi-meter I could measure a resistance
of 1-5 Mohm on this substance.

Old glue seem to be a bad thing to have on PC-boards :-)

73 de Lars, sm6rpz
--
Lars E. Pettersson | Chalmers University of Technology
| Gothenburg, SWEDEN