Sony KV 1212

[DaveWM]

Q801 resistance readings are way off, I know transistor stuff is not as reliable as far as resistance reading go, but will pull the trans anyway and check out of circuit.

[DaveWM]

that was a wild goose chase. The ground of the chassis is connected to one side of the fly pin 10 NOT the 20v supply shown on the sams (where I get a 290 ohm reading). So the base of the horz out only sees the winding in the fly to ground, which is less than 1 ohm. So the resistance check was not good. I did pull the trans and it was fine. I did not pull the "horz conv" trans which is what drives the fly for the HV. Its kinda confusing as there is a separate trans just for the yoke.

[DaveWM]

found it, bad boot up cap 519, pics coming

[DaveWM]

https://www.youtube.com/watch?v=EW7q0r4sYiY

guess if I am going to work on this SS stuff and ESR meter would come in handy. Or could just use the audio tone method for a cheap alternative.

[ChrisW6ATV]

Originally Posted by DaveWM

found it, bad boot up cap 519, pics coming

Nice to hear that you found the problem, and it was a cheap fix. I have repaired a lot of Sony monitors that went dead due to one or more bad capacitors in their start-up power supplies.

Yes, an ESR meter is an excellent thing to have when working on solid-state equipment.

[DaveWM]

a few other less obvious issues remained

Horz width and pin cushion pretty much did not work, I replaced a 10uf cap in the horz out circuit, took care of that.

Remaining issue:

if you turn down the brigntness you can cut off the screen (video or raster does not matter), all but the edges both left and right remain. its not as bad if you turn up the brightness but the edges (about 1/4" vert bands on both the right and left side) are always brighter (you can still see content with video if you have a signal, or if no signal just raster on the edges).

I am guessing here that something in the brighness circuit is being effected at the horz rate (as each line is effected but the top and bottom horz is normal). As if the scan across starts out bright for 1/4 inch, then there is a bias change and it get darker (constant) until the last 1/4 inch where it get brighter again for each scan line.

I am going to concentrate on that area, starting with the ABL since it seems like it would be the area that would mess up with both raster and Video content.

I am guessing the blanking would only mess up on video where there is a blanking pulse (maybe not thinking that corectly have to go look at that again), so presume it should be ok. Same with video amp stages.

there is a ABL transistor that gets a horz pulse from the fly, and there is a cap on the collector that looks like its function would be to filter the output from the transistor. So if the cap is open the transistor switching at the horz rate would def goof the bias up of the video out (tied to this ABL transistor).

[DaveWM]

bridged those caps in the ABL no help.

maybe the blanking but will use the scope to confirm whats going on.

[DaveWM]

forgot to add the pic