The left side of my LG plasma has vertical lines. right side has clear picture.

TCON failure

T con board issue.

Hello,

IF YOU HAVE A SOLID BLACK LINE RUNNING VERTICALLY THEN YOU HAVE A FAULTY MATRIX INVERTER. IF CENTRAL THE MAIN VERTICAL INVERTER NEEDS CHANGED. LEFT = LEFT VERTICAL INVERTER RIGHT=RIGHT.........

ANOTHER WAY TO GET THIS FAULT IS WORN OR DAMAGED RIBBON/PLASTIC GOING FROM THE SCREEN MATRIX TO THE INVERTER

HOPE THIS WILL HELP IN SOLVING THE PROBLEM.....

I know this post is old,
But I had the same problem.
I was able to fix it.
Heres a write up I did on the "How To".
I added pictures and diagrams too.http://jasonkoller.blogspot.com/2011/02/lg-du-42px12x-plasma-tv-fix.html

The screen does not work properly .Ribbon wire fails.

The panel is almost certainly bad. The only fix for this is to replace the whole panel which would cost more than the whole TV.

if you can still see the picture its most likely the control board that's going bad, you will still need a tech out to fix the issue.

I solved the same problem by replacing my digital board. Cost $118.00. Been working perfectly for several months now.

LG service is non- existent . The only solution that I can suggest is "Give a wide berh to LG products. Dont ever touch any"

The vertical line, in my case, was due to a bad contact on the flexible printed circuit. I fixed the problem by using a piece of a rubber eraser to apply downward pressure on the flexible circuit as shown in the picture. To locate the faulty section lightly push on the flexible circuit from lef to right untill the line dissapears.