Zenith 24h20 Porthole

[miniman82]

Well, the schematic does show 2v at the cathode so I'd expect the first grid to sit somewhere around 0 or something negative. If the cathode is low, I'd suspect the cathode resistor and bypass cap. If the grid is high, look at that integrator or the 15k resistor next to it. Also check the voltage at the sync clipper plate and the resistors connecting it to the vert tube.

[leadlike]

Well, checked all the resistors between the clipper plate (which is at normal voltage) and the vert osc grid and found a few out of tolerance ones. Voltage went up to 50v on the osc plate as a result.

Lifted the grid lead to see how much it was loading down the plate voltage, and it went up to 67 volts, so you're right, Miniman, the grid is improperly biased and loading down plate voltage.

Grid voltage sits at about .1 volts, cathode voltage is dead on at 2 volts. If I get time tonight, I will work on making Wa2ise's integrator and see what happens.