[morzh]

Questions:

1. Is there such thing as the voltage diagram for 39-690?
2. The reason(s): a)well, it's just nice in general to have it, it is a very helpful piece of documentation, and b) well, right now is exactly the case where I could use it.

I decided to listen to the tweeters, and while at it, I measured the voltages across their field coils. On one of them the voltage is 80-plus Volts, on the other - 44 Volts. While the input voltages before the coils are close, the outputs are different.
The coil that goes to the tuner chassis and connects to the R69, a 500 Ohm resistance, is the one whose output is lower and the dropout across the coil over 80V. This will result in over 11W dissipation (vs under 4W for the other tweeter coil). Dunno if it is normal or not.

Otherwise, the radio sounds nice, considering the patched main speaker, open volume suppressor long wire, and a somewhat scratchy volume control (I'm reluctant to open the dual ganged potentiometer) and the speakers being on the table right now.