This BassOD I found.....

[Bernardduur]

OK, I found this schematic on the net and I try to understand it.

What does the circuit on bottom, right do (fed by 6.3V, not the heater).

Thanks!

BTW, anyone knows this schematic?

[cd]

Powers the relays which do channel switching.

[Bernardduur]

Ah, I get it. Thanks!