Zenith Hybrid Low HV

[Jon1967us]

Rescued this set a couple weeks ago. It fires up and has a good picture, out of the chute, but the width is deficient due to low HV. Hor and vert are solid, with no sync issues.

HV cannot be adjusted above approx 18kv. At this maximum, I have the HO cathode current at 230mA (235 is value on schematic)

Checking around the horizontal section through the boost. I found the following:

Boost voltage read off C131 is 750v (should be 850)
C131 is a white Elmenco, but tests accurately and very little leakage seen on my Knight capacitor meter. B+ going into C131 is where it should be, at 250v.
Boost off of C132 is also about 100v short of the 820 on the Schematic.

Voltages are more or less normal along H-osc and discharge. However, voltages are a bit off on V3: pins 11 (190v) and 5 (-78). Waveforms appear to look ok on V2a, V2b.


V3, pin 5

Finally, have subbed V2, V3 and V4, with no improvement.