1951 Zenith 16" Porthole

[Electronic M]

Originally Posted by Radiotronman

It's got obvious sync issues that I'll have to solve, but what is strange, is if I turn the volume all of the way down, the left side of the screen will get brighter, further over and the sync will somewhat stabilize. Any thoughts?

Now this tells us something. Some sets used the audio output tube as part of the B+ voltage divider (instead of a dropping resistor they used a tube to put that energy to work). On sets with that form of stacked B+ if the audio output stage is miss-biased or otherwise not working correctly it will reduce B+ to other stages that it is the B+ dropper for. I recommend voltage checks in the audio out stage with the volume low and high...You may also want to scope the lower B+ rail that comes from the audio output cathode to see if it is not filtering well.