[Elecraft] K2 audio output low after upgrades

[Iain Kelly M0PCB]

Greetings list,

I've been assisting my partner Chloe M0GEJ with some upgrades to her K2 
(s/n 5484) and we've come a bit unstuck.

It's  a base K2 with SSB, 160m and the KAF2. She has added the internal 
ATU and the 60M module. She also had to replace a faulty headphone jack 
on the front panel as it had gone u/s. When re-assembled we noticed the 
audio output level is significantly down on what it was before.

The CW side-tone level is unaffected. Both the speaker and phone jack 
are affected. The audio level at maximum volume setting is just below 
normal levels required in headphonesand not very loud for internal 
speaker use.

What we have tried:

  - Full receive and transmit alignment: signals are received well and 
showing good strength on the s-meter, both off-air and from my signal 
generator.
  - RF Gain set to Max
  - Checked RANT selection
  - Checked R1 (AGC Threshold setting)
  - Measured the 5V and 8V lines
  - Replaced U9 (LM380N-08) on the main board in case the old damaged 
headphone jack had caused damage.

I've had a look at Google and not turned up much that has been of much 
further help. Wonder if this has happened to anyone else before?

Any pointers appreciated. If replying to the reflector please copy 
direct to my email address as I may miss responses in the daily digest.

Many thanks,

Iain M0PCB & Chloe M0GEJ