After the set is on for a while, the picture collapses to a single horizontal line in the middle of the screen. Power down the set and immediately power it back on and the picture is back, at least for a while.
Previously I have had problems with occasional thin lines across the bottom of the screen (not there for shows displayed in wide screen)and not there for on-screen menus. I wonder if the two problems are related.
Have worked on tv's before but not for MANY years and was a Electronics Tech in the Navy for 20 years+, so electronics is nothing new to me. But, oh, how it has changed!!!
Just need some suggestions where to start (I know, in the vertical deflection circuit!).
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Re: JVC AV-27790 - single horizontal line
Since Intermitant always inspect the vert ckt for bad solder connections. If not replace the output IC they're cheap and most likely the problem If you still have lines on the top or bottom I would replace all of the electrolytic capacitors in the vert ckt also. Without much test equipment rebuilding the whole little ckt is the best way to go.
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Your problem is due to failure of the vertical scanning circuits in your TV. This is quite common and is caused by aging components. Generally drying out capacitors
You got to be careful not to leave it on too long when the picture collapses, it will burn a permanent line across the screen.
If you are an electronics expert you can fix it if you get a schematic. If not please don't attempt to reapir it yourself since there is high voltage in side the TV.
The problem may get worse with time.
it could be an electrolytic capacitor or the vertical output I.C. in the vertical circuitry,if you remove the rear cover tap on the board in different places and see if the picture fills out or atleast jitters like it might fill out,then it could be just a cold solder joint,then remove the main board and resolder all joints and this should repair the condition you have
If your picture has collapsed to just a horizontal line across the center of the screen, this indicates that your Vertical Output circuit is bad and needs to be serviced by a qualified technician. I hope this helps and thank you for using FixYa!
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
It sounds like a vertical deflection problem. You mentioned you had a white HORIZONTAL LINE in the middle of the screen. If this line runs from left to right across the screen it's in Verticla deflection. If it runs from top to bottom, it's in Horizontal deflection. I am assuming the problem is a Vertical deflaecion problem. The repairs necessary are most likley to replace the vertical capacitors or the verticla deflection chip.
NC Electronic Mills, Wyo USA
I have a similar problem on my CRT computer monitor (AcerView 76c). It is an old screen and I think it is just at the end of its life, much like your TV. Having some background in physics, I would be pretty sure that the problem is with the cathode ray tube's vertical deflection system. The horizontal deflection electrodes are working while the vertical one is not. This results in a display of a single horizontal line (or in my case, a few superimposed) in the centre of the screen. Where both X and Y (horizontal and vertical) deflectors fail then the electron gun firing would result in a single bright spot in the dead-centre of the screen.
So really, we have no choice but to move on and buy a new set as repair is probably just as, if not more, expensive than replacement with a new device. Seeing as your post was in 2007, I hope you managed to solve the problem.