[Elecraft] No Sidetone on K2

[Trevor Day]

Hi All,
I am posting this on behalf of a friend currently without internet 
access.  He has recently completed his K2 but has somehow lost sidetone. 
It did work at one time!

All other functions appear to be correct and the tx radiates in cw mode.
He has not included the KIO2 option, so we checked U6 pin 25 on the 
control board.  This should produce an ac waveform when keyed, but only 
5v dc is measured whether keyed or not.

Just in case the sidetone source had been accidentally changed, we have 
checked using Menu, ST_L, Display and confirmed that the source is set 
to U6 p 25.  Incidentally, when selecting Menu. ST_L, no sidetone is 
heard either although the rx audio mutes as expected.

As the sidetone is not present at pin 25 of U6 I am unable to progress 
this fault further.

The MCU may of course have developed a fault, but if that is the case it 
appears to only affect sidetone.

Any ideas anyone?
Thanks, Trev G3ZYY obo M0CTO

-- 
Trevor Day