Magnavox T931

[LukeSimon]

1967 Magnavox T931



I need help: this TV has AFT, which can be disabled via a switch on the back, but I can’t find the fine tuning dial. How is fine tuning done on this TV? The outer dial changes the VHF channel number and the inner dial changes UHF channels number. The Sams schematic is cryptic. It indicates a manual fine tuning dial exists, but it is not clear what they are indicating.



The picture tube tests good.



I powered up the TV gradually using a variac, dim bulb, kill-a-watt, and then removed the dim bulb. At full voltage, the TV uses 290 watts. The Sams lists 310 watts, so not too far off. The problems: audio volume is weak even at max volume, brightness must be turned all the way up to display a picture, color is not working, reception is weak, focus is bad, and I can hear a clicking or ticking sound every few seconds from the HV cage. After 15 minutes of warm up, reception got better, which suggests some of the tubes need to be replaced.


I will measure B+, boosted B+, and ultor voltages tomorrow to track down the brightness and focus issues. Again, the picture tube tests good, so the chassis must be applying the wrong voltages to picture tube electrodes.

Please help me answer the following questions:

1. How is manual VHF fine tuning performed? Is the UHF dial used for fine tuning of VHF?
2. Can I use a 40kv rated probe for measuring focus voltage?
3. How should I fix the clicking / ticking sound coming from the HV cage?