Thread: Sony KV 1212
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Old 03-03-2014, 09:22 AM
DaveWM DaveWM is offline
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Join Date: Feb 2009
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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).
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