[Elecraft] K2 Problem: Audio Stuck in "Mute"

[k6se@juno.com]

Hi, Jim,

You wrote:

"Since "/mute" means "not muted" then the logic all looks appropriate. My
problem is simply no audio out although the side-tone works OK. Also
there is no change is hiss with the audio gain although the 0 to 5K ohms
from the pot can be seen across VOL1 and VOL2 as expected.   Any ideas? I
may try to feed in a 1KHz audio signal just to test the amplifier, U9,
itself... Any suggestions are welcomed."
==========
Gary Surrency at support@elecraft.com is the one who can help you the
most, but I can offer suggestions because I went through the same
exercise when I got to the same point you're at.

My receiver was *very* weak when I got to "Alignment and Test, Part II". 
The problem was a bad solder joint at pin 8 of U12 on the RF board.  It's
unlikely you have that exact same problem, but signal tracing pinpointed
the problem.

I assume that all of the tests on pages 57 through 60 of the manual went
ok, and that you're stuck on page 61 (I.F. Amplifier Alignment).

First I'd make sure jumper wires R18, R19, W1, W2, W3, W5, and W6 are in
place on the RF board.

Next, make sure that toroids RFC14, RFC16, T5, T6, and L33 have good
solder connections to their leads and that T5 & T6 are installed
correctly (with their leads in the correct holes).

Ensure that all diodes are installed with the correct polarity.

Ensure that no ICs are installed backwards.

If the voltages on the RF board transistors are ok, it's time to connect
a signal generator to the antenna input and start signal tracing with
your RF probe/DMM.  Set the signal generator for output on the 40-meter
band and follow the procedure beginning on page 10 of Appendix E.

GL, 73 , de Earl, K6SE