TS-930 little to no output in AM mode
I bought this radio a few months back and after getting a little familiar with it, (my first HF radio) I've realized that the AM mode is not working correctly.
I easily get 110 watts in CW, 55 watts in Tune, and I get swings of 80+ on SSB, so I'm assuming the finals are good.
Symptoms: If I max out the CAR on AM I only get 1-8 watts for a carrier (depending on the frequency I'm tuned to. If I put an audio signal into the radio I can get the power up to 10-20 watts at the modulation peaks. The AM reception is great, so the problem has to be somewhere in the AM TX circuit.
Observations: Only in AM, I do not see any ALC movement. I also don't hear my voice when the MONI is engaged (like on SSB). I don't know if it's supposed to work the same as SSB. Can someone confirm that? Power is measured into a dummy load (Bird 82A) and the power levels I observe agree between the internal meter of the radio, as well as a new external power/SWR meter.
This radio is a later-production model (s/n: 508xxxx). When I compare mine to the service manual schematics, I see a lot of discrepancies from the post s/n: 310xxxx schematic; but it does look the closest of the 2-generations shown; compared to mine.
I heard these radios are notorious for bad solder joints so I desoldered and resoldered every connection on the RF board, but it did not improve anything.
Anyone else ever had this problem?
Any ideas of where to poke-at next?