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.