After a few minutes picture shrinks to single line on screen and then powers off
TV is about 5 years old. When you first turn it on, it has a clear bright picture (normal). After a few minutes the screen shrinks rapidly to a single line and the tv powers off (reminds me of the old B/W Zenith console my folks had when I was a kid). Second and repeated attempts to turn it on result in the same, only the time before the screen shrinks gets shorter and shorter until it just turns on, flashes the single line and shuts off.
I would like to know if this is a major repair or a simple repair and approximately how much.
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Re: after a few minutes picture shrinks to single line on...
Since the set works initially, there are likely poor solder connections at the vertical IC. If this is not addressed soon, the IC will fail and need to be replaced. The vertical IC is a small flat IC with about 11 pins or so that may be marked LA7837 or something similar. Try resoldering the pins first. If that fails to resolve the problem, replace teh IC. Feel free to post the marking here so I can verify you have the correct one.
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The JVC sets are well known for this type of problem, the tv has a vertical deflection issue needs a few small parts and a touch up on the vertical ic, causes the set to shutdown. I recommend a tv technician for the repair.
There is an IC which controls the vertical deflection and over the course of a few (or 8) years with the set heating up and cooling off some of the connections work their way loose causing the symptoms you describe. If you were to bang on the side of the set you could likely "pop" it back in but this is not a good solution. The vertical IC needs to be re-soldered. This is especially common in Panasonic sets. About 10 minutes with a soldering iron should have it worked out.
If you're handy with a soldering iron I can tell you what to look for.
This is caused due to random falure of vertical scan circuits. It generally is caused by dried out capacitors or bad driver IC. Unfortunately it will get worse. If you fail to turn the TV off quickly you will burn a permenant horizontal line on the tube. Trip to the repair shop I am afraid.
All symptoms indicate a problem in the vertical circuit,the first thing to look for will be loose conection on the vertical output IC,sometimes this IC goes bad completly and it needs to be replaced.If you are familiar with soldering electronics you can take care of it but if you are not too familiar you can play it safe and take it to a servicer ,it will be a lot less expensive than if they come to your house.Let Us know how it goes or if you need more information.
It is in the power supply or I would guess most likly in the horizontal sweep section of the tV set. MOST of the time, if the power supply is going lower in voltage, the set will shrink in width,BUT will also shrink in vertical size. If this is not happening, then I would say it is in the horizontal drive circuit. This is not a circuit a user should be experimenting with, as this is the HIGH VOLTAGE circuit and can pack a mean punch! Please if the sets less the 4 to 5 years old you may want to concider an estimate or replacing the set. Its all up to you. GOOD LUCK