Interesting schematic. They use a dual selenium rectifier to supply DC to the filament of the mixer/oscillator. The filament winding for the 5Y3 is also used for the CRT. I guess they were concerned about having the CRT filament too close to the ground and filament to cathode shorts. GE did the same thing on its Portacolor set.
I figure the replacement transformer didn't have the two extra taps for the 5Y3, so they installed a dropping resistor between the 390V and 310V sources.
|