VERTICAL line across TV screen & Musings on TV's

Technician Join date : 2018-08-01

Back when I was a teenager I had an old B&W set in my room that I watched quite a bit. The picture tube was badly worn and I used to boost it about once a month to keep it watchable. I had a CRT checker by this time. Eventually this procedure came to an end because the plastic that was used in the yoke continued to fracture, deteriorate and eventually fell apart. Because of the bad picture tube I didn't try to get another yoke. Looking back on it, probably both items could have been bought at the time for a reasonable sum of money. I'm sure the local parts house would have been glad to get such items off their inventory.

Some old sets I boosted the picture tube on lasted a really long time and far as I know didn't go bad again. I passed on such sets to others that needed one. My Dad was a good example of a "customer" that wasn't really concerned with getting a good picture. He would watch almost anything as long as the sound was good.

Moderator Join date : 2010-11-22

Problem:
Bright white line from top to bottom of set in the middle.

To avoid confusion- (I hope).
A horizontal line across the screen means vertical deflection problem.
A vertical line across the screen means horizontal deflection problem.
Yeah, I know. It doesn't seem right to the layman, but it is correct.

Here is a repair hint for this problem:
Look for open yoke winding or yoke connector problem.
this was the most common cause of this. About 90% of the time I found the Molex (tm) style connector pins on the circuit board had lost their solder.
If the customer had not run the TV in this condition after it happened, the set should be fine after re-soldering. I have very seldom seen a yoke fail. I have replaced less than 6 in a 50+ year history of repairing sets, unless the owner damaged the yoke physically.
If they ran it that way for a long time, they likely burned a line in the CRT.

The so called "Bonded" yokes can come loose from the CRT also causing some odd picture and purity problems. I did run across this many times over the years. Some AQUARIUM grade* RTV silicon will fix this. Apply liberally and block yoke in correct position until it dries. Be sure to verify you have it in the correct position. And yeah, it can happen to CRT monitors too.

PS: The same can happen to the yoke connector causing a horizontal line across the screen, (Vertical sweep failure). I saw this about 10% of the time.

PPS:
If you have a set with a line across the CRT you are trying to repair, TURN DOWN THE BRIGHTNESS. Otherwise you will cause a phosphor burn in the CRT. THIS CAN HAPPEN IN UNDER A MINUTE- trust me on this. I have seen it happen.
Remember back to the old video arcade games with the burns in the CRT form the game displaying the same picture for hours on end.

PPPS: I had a customer bring in a set with no vertical sweep and they had ran it for 2 weeks to "Listen to the sound". It had almost a 1/4" wide phosphor burn across the CRT.
TV looked like crap after I got is repaired, but the customer didn't mind the line. Shocked

* Aquariun grade RTV does not have any nasty gassing that can harm the circuit boards or components. Regular RTV can cause some nasty problems.

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