There are 3 sections dealing with that mic. PA is one, AM is another and SSB the third one - the only common between all three is the mic - which seems to make it to the main PCB, but PA works - so lets presume that is ok, the other two AM and SSB, require the use of TR33, TR32 and TR31 - but they need communication from the FRONT panels USB/AM/LSB switch - so D38 goes hi in TX mode - and mutes the Audio Amp - that seems to work - so the Mic amp - needs 8 volts all the time - so D36 looks back at the PLL - so when you ground Mic pin 3 - the TR32 "looks" to PLL to see if its' in lock - well...is it? You say you get carrier - is it on frequency or just showing stuff on the meter? TX would not go on if PLL is out of lock...
So if TR32 is bad, or PLL out of lock is my only guess...
TR32 is my only last guess, for it is the key to this problem. Mic amp is powered all the time by an 8 volt regulator - so you need to verify the Mic amp "stays" powered - here is a quandary. IT goes back to the front panel - either the CB PA switch one of the poles is "connecting" but the other side isn't. Another factor is the USB/AM/LSB switch - that has two poles and one side switches in 8 volts to turn on a bunch of stuff in SSB mode and puts the AM regulator into full power mode - meaning carrier power in AM mode big time if possible - its' not supposed to.
The olther part of that USB/AM/LSB mode switch toggles the different lines for shift in frequency - and sets AN612 - Using the output of the Mic amp - to send audio in to the TX strip for mixing.
So by your postings you're not having frequency problems - just making it TX again.
You have a TX light but no audio...yet PA works.
Replaced TR31, TR32 and TR33 - got something working...just not audio (at least continuous)and SSB mode you get nothing too...TR27 removed - no effect - replaced.
You'll need to grab a schematic because you need to perform voltage checks to locate a dead section - -this may simply be due to a need for recapping - but when you have physical damage like the front panel shows - there's a lot of tiny work in there that can tear from shearing...
This is a head scratcher?
