Sony question: "Black 'n Blue"

[AlwaysLyceum]

Just a quick question. I recently bought a 1987 19" Sony Trinitron, model KV-1926R, and is a part of my TV-T, which there is a picture of it in another thread. Anyway, this is the only TV that I have in which colors that should be black are more of a navy blue. What type of problem is this? I'm not familiar with anything inside TVs whatsoever, but I'm pretty sure it has nothing to do with the front control knobs (sharpness, bright, color, hue). I know you really can't take pictures of TV color problems, but I'm uploading these just for kicks really. BTW, I don't know how to insert pictures within the body of a threat without it already being on the internet. So, anyway, why are black suits navy blue on this TV?

[radiotvnut]

I think I have that same set, buried in the shop. It was a TV shop reject that only needed minor repair and I watched it for years. And, I've had some other similar Sony's. On every one of them, I had to play with the bias and drive controls on the CRT neck board in order to eliminate problems similar to what you're having.

[Eric H]

Like he said, probably a tracking issue, could be just an adjustment or it could be the CRT is dying, the latter wouldn't be unusual on a Sony of that vintage.

[VintagePC]

While I doubt it, a short/low resistance path from the blue gun to ground could produce something like this.

As could a fried video amplifier chip (usually on the CRT neck board.)

[kx250rider]

I'd say, based on experience, that the CRT is weak. The red and green cathodes seem to fail earlier than the blue. IF this is the problem, you might be able to buy a little time by re-tracking the tube. There are a number of "on the fly" procedures for it, since the book procedure doesn't work so well on a poor CRT. There should be 3 G2 controls and 2 Drive controls on the CRT socket board.

Quick procedure:

Turn COLOR to min, and tune in a snowy screen (no signal).

Turn PICTURE and BRIGHT to mid

Turn all 3 G2 controls to about 1/3 from min (looking from the back of the TV, so if you don't have a screwdriver small enough to turn through the holes in the board, that's opposite of course)

Turn the 2 Drive controls to mid

Turn the SCREEN control (on flyback in some, or a larger pot on the socket board to min, and then advance it til you barely (BARELY) see a the screen in one color. Leave it there, and go to the G2 controls, and turn up the one that isn't showing on the screen, and try for a grayish picture. Now give the TV a signal, and see if the dark areas of the scenes are still gray, and set the Drives to try to get the bright parts close to white. You can play with the G2s a little, and if overall too dim, you can nudge the Screen control up slightly, but not much, as that will overdrive the CRT as well as throw off all the adjustments again.

Charles

[andy]

...

[Findm-Keepm]

Originally Posted by kx250rider

I'd say, based on experience, that the CRT is weak. Charles

Yep. The only problems we saw with those Sony KV-1926's were the cold solder joints on the IF board, the bad 4.7@250V on the deflection board that caused a shading, and bad CRTs - with the green taking a vacation first.

Good sets, once the gremlins were gone. I fixed one for a sailor/buddy that took it to Japan for 2 years in the 90's, and brought it back here to the states. It is still plugging along as an Xbox set for his grandson.

Cheers,

[kx250rider]

Originally Posted by andy

You won't find 3 G2 controls on a Trinitron since there's only one G2 in the gun. A Sony of that age will have 3 background controls (labeled BKG), and 2 drive controls.

I stand corrected... I knew something didn't look right when I wrote that .

Right procedure; wrong name. It's been a few years since I worked on those regularly.

Charles