[jshorva65]

Most 3-way units had completely separate power supplies for the TV and radio/phono sections, especially separate-chassis arrangements like the RCA 730TV1 and 730TV2. The master on/off was usually part of the volume control or sometimes the tone control. The primary circuit of the power transformer on the audio chassis was connected so that the master on/off alone would control it. The TV chassis' power switch was ganged to the mode switch such that the tv power transformer primary was shunted across the audio power transformer's primary in television mode. Many radio/TV combo units left the heaters energized but switched the B+. Some compact and low-priced models merely cut the drive for the sweep circuits and biased the sweep output tubes to cutoff (thus killing HV and blanking the raster) such that the mode switch handled only grid-circuit currents, eliminating the need for high-current switch contacts. Certainly it was a waste of power and tube life, but it could be accomplished with cheap parts and the power company and service shops got plenty of business ... all those extra watthours and replacing weak tubes.