Hello Amanda,
Is the line on the screen about 2-3 inches wide?
Which model tv do you have? I have an HP PL4272N with the same problem(the internals migh be the same as the LG 42PC5D).
Are you a technician? If not, you'll need to have one look at it to fix that problem.
Here's what I found with mine... there are several ribbon cables connected from the buffer logic boards to the screen. On these cables, there is some kinda fuse embedded. The fuse on the cable, adjacent to the line on the screen was burnt out (two burn holes were visible on the fuse. You can check yours, if this is not the problem, maybe its the buffer logic board.
My Problem... these cables might not be replaceable, so only way to fix it might be to replace the display panel... which will probably cost the same as buying a new tv! Suggestions anyone?
Hope this helps...
John, May 2010
