Zenith 24h20 Porthole

[leadlike]

Thanks! I may wind up making a new one.

Measuring voltages, everything comes up normal, with the exception of the plate of the vertical oscillator is way too low: I'm getting 45 volts on my digital multimeter, when my Rider's schematic puts it at 74 volts. The plate is only two resistors away from the B+ feed, so I replaced them as they were out of tolerance, but still get the same low voltage. Swapping tubes has no effect, either.

As it is, the picture I get "floats" vertically, it does a half-hearted attempt to lock, before drifting away again. The vertical flipping doesn't increase in frequency, there just doesn't seem to be any lock. Interlace is also poor. The effect is the same whether injecting signal at the video grid or through the antenna.