I ran into one of these stupid Zeniths. plauged with CRT problems, but this one surprisingly had a pretty good picture.
Well the initial problem was after warm up, the vertical would collapse to a
5 inch band across the screen. most likley a vertical cap, but more likely bad solder joints around the vertical circuit. also to note some bad solder around the CRT neck board.
Now, the set is dead. when you plug the set in, you can hear a sick whine comming from the power SMPS transformer in standby. if you hit the power button, you can hear the degauss relay click, a strong low-pitch whine, and instantly, the relay clicks off again, and power goes back into standby.
HOT tests fine. any ideas? im suspecting the two caps on the primary of the SMPS controller IC.