You are just confusing yourself making measurements when pushing program audio through the amp. DON'T.
You will NOT run the amplifiers into speakers (OR headphones) during these tests:
You WILL individually remove each output transistor from the duff channel and test each of them with the six way diode test.
You WILL then test to be sure that each 0.5 ohm emitter resistor connected to that output transistor is intact
You WILL then test to be sure that each 4.7 ohm base resistor connected to that output transistor is intact.
With all output transistors removed from the duff channel, you will power it up to run DC balance tests.
The driver transistors Q9 & Q11 along with R41 will ensure that the DC balance is adjustable, and you should adjust the DC balance to 0.000v
At that point measure referenced to ground the emitter base and collector voltages of EVERY transistor, and post them.
You CAN use the good channel's voltages at those points as examples of correct voltages.
You could do a shortcut (dangerous) when you have the +9v and +6v as in your earlier post - with NO audio, and check for 0.6v between each transistor's emitter(black dmm lead) and base (red dmm lead).
positive 0.6v for npn transistors, negative 0.6v for pnp transistors.
That should be the case for the operating channel, but NOT for the duff channel.
When you find the error, you will probably find either a shorted output transistor, as well as an open 4.7 ohm resistor, or an open 0.5 ohm resistor.
LEAVE the STV-4h / VR3 ALONE, that 9v to 6v reading shows that it is doing it's job.
Done accurately - these voltages will tell me many things.
Tip: when measuring voltages around the current source (Q5, Q6) don't reference to ground, connect the black dmm lead to the +48v pin 7 power rail.
The numbers may be negative, but they will be of the correct magnitude and precision.
