My Toshiba 36A50 had the same issue.The picture would gradually shrink until it no longer appeared and there was only a thin line running from left-to-right across the center of the screen.The volume still worked perfect.
From information I gleaned from this site and others, I removed the main circuit board and flipped it over to re-solder the pins going to the Vertical IC (TA8427K).This IC is right about center of the board mounted on an aluminum heatsink so it is soldered in vertically.You can easily see the part number on the IC and it is the only one of that part number.Additionally, the silk-screen on the PC board has a QC301 next to it identifying the part.
After I re-soldered it, the TV works excellent.I just did this yesterday afternoon 10.26.08.
Thinks to note that have been pointed out by others:
There is high voltage in the TV even after the power is removed.There are several sites where they tell you how to remove the power.
Make a note of all connections.Most of the connectors are keyed to go in only one way but some you can turn the connector either way.Write down all the information and take some digital pictures before you disconnect everything.
As was pointed out but other people, the Vertical IC and/or some of the surrounding capacitors may be defective and need replacement.Its possible that your local Radio Shack may have what you need but I would not count on it.A possible source for parts is www.digikey.com.
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Re: no vertical output
Dear friend for what you are saying you have some loose connection on the main board,you need to get a bright light a soldering iron and some solder wire and re-do the connection that look loose.
wish you luck
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If the line displayed is a very thin one, and across the center of the screen, it is a problem with its vertical sweep. Check and replace the vertical output IC. If you wish to get more details, and schematic similar to LG, check the site linked here. Check what is the IC number used with your TV. Check for it. http://electronicshelponline.blogspot.com/ Pull up previous posts there, either by type
in the Brand name to your set in its search box, or view it in Mosaic
The screen voltage to the picture tube is more than normal. Adjust it by the help of screen pot-meter integrated with Line Output Transformer. Visit the site named 'Electro-help' for more details. Check this link and select the site named above. View it in
'Flip card' option, which can be selected from the drop down box menu at
the left top corner or the display window. It will make search easy.
You haven't specifed nothing about the model number or brand name of your flat panel teleivison. i assumes that it to be a picture tube based one and posts this solution before you.
A thin horizontal line across the screen with sound output is OK, is the sympton of total failure of vertical sweep. This may be due to failure of vertical output IC or loose solder terminals of that IC. The vertical output IC will heat up while working, and repeated heating and cooling may make its solder terminals to get loose. Just open your TV, pull out the board that contains vertcial output section, turn it upside down, resolder all the solder terminals of that IC by applying a little more solder, without making any solder bridge in between terminals. Check the voltage to the vertical output IC also. If this resoldering method does not help you, replace the vertical IC itself with same type and number will solve your TVs problem. OK.
That TV uses the PTK195 chassis, and the fact that you see only a thin line for each color near the bottom of the screen tells me your vertical output IC has stopped working, and is putting a small DC voltage across the yokes. I have seen this caused by a defective vertical output IC and I have also seen vertical problems caused by a small CRT coolant leak which drips onto the main board near the vertical output IC. If you do not have experience servicing the PTK195 chassis than have a qualified tech handle it for you.
this symptom, sometimes called the tube light effect, it is characterised by a bright thin horizontal line across the middle of the screen. this symptom is caused by a breakdown in the vertical deflection circuit. hence maybe the trouble maybe in the vertical oscillator, amplifier or output circuits. but if all i have said is not clear to you, better bring it to a qualified tv technician. good luck!
I know I have seen thin lines in the past on older CRT monitors, these are usually wires which support the aperture grill.
LCD is just a panel so this must be something different. What color is the line? It is probably an error in the scanning process.
sounds like you have a vertical sweep problem. Where the fault lies cpuld be the vertical output IC the verticle b+ feed, could be the capacitors in the vertical circuit?? Your gonna need to troubleshoot thr vrtical circuit if your not a tech thin my advise is to take the set to a pro for sn est. Good Luck