Sony KV-9200 Uneven Raster

[vol.2]

Originally Posted by Popester

Actually I didn’t think the second photo of the set looked too bad. Some of that bowing of the picture lines you have highlighted look like pincushion circuit issues. Might want to replace electrolytics in that circuit.

All of the electrolytics have been replaced. They all tested way out and some of them were open or had destroyed legs.


In any case, I'm pretty sure I found the smoking gun. If you look at this portion of the schematic, I circled where I found a missing voltage on the collector of Q512. It's called the convergence output on the Sam's, but the SONY service manual calls it the HOT. It's supposed to have a 750Vpkpk signal on it, but it doesn't get anywhere near that high, and it's supposed to be 108VDC, but I only measure ~1.6V. There is about 114V present on the other side of that inductor.

Amazingly, there's enough travel in the screen geometry controls to bring it up to about the correct size when the HV Size are at their full travel, but I think this is why the geometry is messed up, and also why there is an uneven brightness on the raster (because I have to use the HCENT to shift the screen all the way to one side).

I found a transistor to replace it, but it will be some time before it comes in the mail.