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Re: A horizonal line across screen
HI YOU dont want to change vertical Tube.i think it is only a convergence problem.Sounds like convergence are off. Go to menu and find tv convergence and reset. This deals with red, blue, and green. IF YOU WANT TO CHANGE CATHODE RAY TUBE IT COSTS 300$
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the vertical drive ic that drives the yoke for vertical sweep has blown.
sometimes it is solder problems like sharp and toshiba had.
the part is 10$ the pc board will label it ,the yoke is the coil setup on the picture tube.if you follow the wiring half goes to the horizontal drive,and the others to the vertical section.the chip drives the coil directly.there are VERY high voltages in there ,even turned off. the pix tube cap on top is 30000v. like a stun gun.the horizontal drive 2000 volts and the main power supply 165 volts dc high current.you need a special setup to discharge the picture tube.
vertical output ic needs to be resoldered. careful leaving that bright line displayed on the screen as this will cause a permanent phosphor burn into the tube. this can not be corrected once burned unless you replace the tube. mch
Sounds to me you have a cold solder joint ( loose solder connection ) on the printer circuit board around or on the vertical chip or on one of the vertical capacitors. You may also have a bad vertical chip or a bad vertical capacitor, but I doubt it since it did come and go. I'de get a soldering iron and some solder and touch up the connections. I will remind you that you need to always excersise saftey by making sure, before removing the back, unplug the TV from the wall, and use care not to come in contact with the large red wire going to the back of the picture tube as the picture tube can be turned off and still store lots of voltage ( up to 35,000 volts). Always stay safe and when soldering, use care not to run solder across places that will make a short.
Good Luck and I hope this helps
Ed Meshechek ( Radio Man )
The picture tube itself is not longer being manufactured and the replacement might exceed the price of a new TV.
The vertical line you see on the picture tube is not a failure with the picture tube but a different part inside the circuitry.
This is a vertical circuit problem that is either bad connections on the vertical IC or a defective IC. If you can solder, you can fix this yourself. Look for a small flat IC attached to a heatsink with about 9-11 pins. It may be marked LA7837 or something similar. Try resoldering the pins first. If that fails to resolve the problem, replace the IC. There may be defective caps in the circuit as well, but those don't usually cause complete vertical failure. If the picture does not return fully, update this and we'll continue on to the next step.
Check first for bad solder on the vertical IC, Im not sure for your set as I do not have the service manual, but it may be location IC301. If after resoldering it does not fix it you may have to replace it and you should replace the electrolytic capacitors in the vertical section.
Hope this helps.