No, but if he's got issues with the PA amp transistor - TR26 may somehow be coming up or tuning on, not sure of the wiring if any was repaired in this...
The above is some thoughts as to why I'm asking this stuff...
It's because I had to track down a dirty CB/PA switch caused by an operator spilling (whatever) onto the front dashboard of his Cobra 142 - since it's a similar board - to see something "die" see above...
- Lite - BLUE - DIODE matrix of the MODES - Keeps 7.8MHz IF working
- GOLD - TR31 if in AM mode - turns on and sends power to TR21 forcing Audio out of the line to AN612 - and sends it to the Audio Amp instead.
- GREEN - TX Power GOOD LOCK switch to let Radio go into TX mode - routes out to CB/PA switch looks at Pin 5 of MIC socket if in CB - else OPEN in PA - turning off TX mode not matter what LOCK says. PA works independently but USES PIN5 of MIC socket
- RED - 8 Volt Constant branch - powers MIC amp and PA Amp strip and AN 612
- Dark Brown - PA Amp - note lines for MIC - although Audio arrives SEPARATELY - it does SEND audio thru same line to Audio AMP as if in AM Mode (TR21 inclusive)
- Lite - Brown - SHARED audio output line from both Mic AMp Thru TR21 and PA Amp directly
You have two places where Audio gets sent into a SHARED line. TR35 handles TX mode when LOCK is good but looks at PIN5 of the Mic socket - one side goes to the MB3756 while one heads to the switch - it has to go to the CB/P{A switch to turn of the TX side but now matter what it runs the Audio Amp. TR35? If it can't send power thru to the CB/PA switch - what does happen? The line from the SWITCH goes to PIN5 of the MIC socket - this turns off the TX side but what does happen when the switch is dirty and yet "held up"?
Now if the AN612 is working - the output of Pin 7 goes here...
It's why I had you (
@wildwinds ) check a cable - for the AN612 also taps this line - and THE FREQUENCY COUNTER DOES TOO! So if there are problems in the cabling - the Frequency counter might not work - but TP3 would show this as really low signal output on an O'scope. - you get a frequency so I can only hope it's strong enough - and if that was the case, you'd only have really low SSB output but would still hear the audio.
Now for the AN612 to the FT3 route, or that shrink-wrap mess of Xtals and Coils - that can still send signal to it, but if the output of the FILTER is bad - IC5 won't see it - so SP5IT is asking what you see on Pin 7 of the AN612 - that Balanced Modulator.
My thoughts on Audio and Dying -
The PA Amp could "latch" and send audio out killing all the MIC amp line because it SHARES the Mic Input from the Dynamike control. So if PA amp came up or if there is an OPEN line or bad CB/PA switch (read dirty internal contacts or harness pinching and/or wiring insulation breaking) I can see where the CB PA switch can be a culprit - when the contacts are not fully thrown in one direction or another - can cause a "Hang up"
I've seen this many cases that the Front Panel got jostled by the user - or just plain dropped, and now the Faceplate to Chassis - making alignment and screws with pins detents and alignment holes nearly impossible to put together because it's warped and the switch toggle levers won't line up to the outline - in short - a dropped radio is a big mess...
Now I'm not saying his radio is dropped, just the Control Panel Faceplate to Switch alignments may be an issue on the extreme ends of each side of that panel. So when you throw the CB/PA switch, the level does not complete it's entire throw so contacts are left barely connected. I've seen Base radios that you can tap a control and it fades out, taps again and it comes back - these types of symptoms are hard to track down easily and quite stubborn to repair because it takes so much time and effort in disassembly and reassembly and alignment all at the same moment to secure the proper tension and spacing so all switches and knobs work with no interference with each other or in their movement.
Just some of the Joys of being the guy others head to when they're tired of it...