Sony KV-9200 Uneven Raster

[vol.2]

Originally Posted by Alex KL-1

A bad driven HOT can cause issues. Normally this acts a switch. An driver error and timing gets wrong. Remembering that H circuits are tuned (at least flyback), so, a wrong timing affects linearity; Gross errors explodes the HOT. Hosc and driver can be suspects in this case.

I've investigated the driver transistors, and I can't find anything funny there. However, I've found that Q501 has a funny voltage.

Q501 is supposed to have a negative voltage (-0.2V) on the base, and yet it has about 1.8V. When I measure the source, it's all correct voltages before the base.

In this case, I assume that the transistor is switched off, and something beyond the collector and emitter is supposed to be sinking current, keeping the base at a negative voltage.

The only thing there I see wrong is the amplitude of the waveform between the phase detector diodes. It's supposed to be 14Vpp, but it's like 10.5Vpp.

I don't have any replacements for the germanium diodes in stock, but I ordered something that should work, so I'll replace them and see if that helps.

[Alex KL-1]

10.5V of amplitude here explains pretty much about image size. Even if C558 is dry perhaps this occurs (bad HOT biasing in cutoff).
About base of Q501, either sync amplitude and HOUT amplitude will affects if it will rectify excess amplitude (and provokes the desired negative base voltage). But any R, C or diode can be culprit in the path. Or, simply the flyback have a very unusual fault and behaves like it are mistuned..... then a experimentation with C560 (the resonant cap one), adding a little or subtracting a little (put a 2nF/1.6kV poliprop in parallel with it), to see if pulses rise. But I advise to try to find the driver cause first.
I just remember to made this in the past in one misterious behaving TV.