11-08-2013, 10:34 PM
Either pin 5 of the 7B7, or pin 4 or 7 of the 7C6 would be B- or negative power supply common.
With a power transformerless set like this, B- is isolated from chassis ground for safety reasons, so you have to sort of hunt for the common negative of the power supply, which is referred to on the schematics as B-.
With a power transformerless set like this, B- is isolated from chassis ground for safety reasons, so you have to sort of hunt for the common negative of the power supply, which is referred to on the schematics as B-.
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
