Riddled TV Repair Forum

nhawlman · Joined: 17 Jun 2008 Posts: 2

My Son was given this TV with NO DUST in the cabinet,
It has a great picture except...

it has three vertical bars on the screen; one each of red, green and blue.
The bars are about 1/3 screen wide.
Sometimes they seem more objectionable than other times,
when they overpower the scene.

We know about high voltage, deflection coils, oscillator circuits, degausing, etc.
And we're handy enough to think we can fix it.
Any help would be greatly appreciated.

Google

Jesse Mack · Joined: 22 May 2008 Posts: 600 Location: The Last Frontier

I am assuming this is a Direct View TV. You are describing a slipped yoke. If the center bar is red, the seperating lines between are diffused (not sharp), simply loosen the yoke and slide it forward. This is not common however. please note that a domed shadow mask can produce a similar condition. To differentiat, note if the deflection yoke is firmly against the rubber wedges. If it is, do not loosen the yoke as it is not the problem. Usually if the problem is a domed shadow mask, the problem will seem to get worse as the set warms up and return to preheating condition when cool.
One more thing. It is possible that the degausing coil has activated out of sequence. To check this, find a gun type of soldering iron. bend the tip either left or right to get it out of the way. Now follow these steps in order
1: turn the set on.
2: turn the soldering iron on.
3: lay the side of the soldering iron against the picture tube. (you will notice a gross distortion in the picture while doing this.)
4: move the iron in a circular motion all over the screen.
5: move the soldering as least 3 feet away from the screen.
6: turn the soldering iron off.
You have just manually degaused the set.

If it happens to be a domed shadow mask, there is nothing you can economically do as this would require a picture tube change. (well, you can check on the price of a tube before deciding if it is economical as I live in alaska and the shipping cost is very high)

Hope this helps.

Jesse

nhawlman · Joined: 17 Jun 2008 Posts: 2

I appreciate the information.
We'll give it a try over the weekend.

Health and Happiness,
Nevin