Quote:
Originally Posted by Notimetolooz
That HV meter looks OK. I haven't seen that model before. Yeah, it could be the capacitor smoothing effect.
A quick and dirty way to check the audio output circuit is to touch the wiper on the volume control with a screwdriver with a finger touching the blade. Don't have the volume control turned down however. You should hear a hum. If this was a hot chassis set you definitely want it plugged into an isolation transformer to do this.
You would need a FM modulated 4.5MHz audio signal to inject to trace the signal further up (from the volume control towards the tuner).
A oscilloscope could enable you to trace the audio from the tuner toward the volume control.
Without those you are left with checking voltages, resistors and tubes, etc.
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This is a early post war split sound set so the sound IF is 21.25MHz NOT 4.5MHz that intercarrier sound sets use.
Also he may be able to get away with a tube AM modulated signal generator...Most tube TV/radio repair grade generators distort the the RF carrier enough to create FM/PM modulation that TV audio systems can detect. I've done this with 2-3 different generators so far.