[bigaudioal]

Originally Posted by Kevin Kuehn

Here's the basic logic:

Both sets of A-B contacts are in parallel. So turning on either the TV or the radio connects AC line voltage to the power transformer primary.

When the TV -only- is switched on, the C-D contacts on the TV volume switch disconnect the radio circuit filaments of V601,602,603,604,605 and the two radio pilot lights.

When the radio -only- is on, the C-D contacts on the radio volume switch disconnect filament voltage from V101,102,V201,202,203,V301,303,304,306,V403,405,40 6 in the TV circuit.

Is there a TV pilot light I'm not accounting for?

Yep, there is a pilot light on the front of the TV. On the schematic, it is all the way on the right side, to the right of the AC line plug. Right now, when I plug in the set it is always on and never goes off unless I unplug the set.