First you need to determine whether or not the problem is in the TV. One way to find out is to see if any of the built-in graphics, such as the menu or the volume indicator, can cover up the problem. Grab the TV remote control and select Menu (or push the Menu button on the TV). If the lines or bars in the picture are masked or hidden by the menu, then the problem is not in the TV, and the reset of this article is irrelevant. But if the artifacts are visible regardless of the presence of the menu, then the problem is in the TV.
Another way to find out if the problem is in the TV is to change how the picture fills the screen. Find the button on the TV remote labeled “WIDE”, “ASPECT”, “P SIZE”, or “ZOOM”. Try pushing that button a few times and see if the lines or bars change position. If the artifacts remain stationary, then the problem is in the TV.
If you determine that you need to replace the display panel but you are not sure if it would be better to buy a new TV, read Is My TV Worth Fixing?
One or more thin (pin stripe), solid, vertical lines of any color - or many thin, solid, vertical lines of random colors
These symptoms mean there is something is wrong with either the display panel, one of the address printed circuit boards, or an electrical connection between them. The best way to fix it is to eliminate all of the possibilities by replacing the whole panel. The new panel will come as an assembly with all of the printed circuit boards it needs, all hooked up and ready to go. (For plasma TVs see Replacing Plasma Display Panels. For LCD or LED TVs see How To Replace LCD and LED Panels.)
A combination of randomly colored, solid, horizontal and vertical lines and solid or semitransparent, randomly colored bars of a non-symmetrical pattern
This symptom always means there’s something is wrong with the panel. The best way to fix it is to replace the whole panel. (For plasma TVs see Replacing Plasma Display Panels. For LCD or LED TVs see How To Replace LCD and LED Panels.)
Exactly half of the picture (left or right) is perfectly okay and the entire other half is not
If you have an LCD TV, the culprit is a defective timing controller (TCON) printed circuit board. This is the board that feeds the picture information to the LCD panel, and centrally mounted near the top or the bottom of the panel.
If you have a plasma TV, the guilty party is the address printed circuit board on that side of the screen. The address boards are mounted either along the top or bottom edge of the plasma panel. See Replacing Circuit Boards
One or more black vertical bars, each from 1 to 3 inches (2.5 to 7.5 cm) wide
This is not the same as “pillarboxing” (the two black bars that you typically see on the left and right side of a narrow 4-by-3 video source). See TV Picture Doesn't Fit Screen for more infomation on this.
If it is an LCD or LED TV, the only way to fix it is to replace the LCD/LED panel. See Replacing LCD and LED Panels.
If it is a plasma TV, it could be a bad address printed circuit board. The address boards are mounted either along the bottom edge of the plasma panel (which is most likely), or along both the top and bottom edges. Or the problem could be that there is something wrong in the panel. To eliminate the ambiguity, the most reliable way to fix the problem is to replace the whole panel, because the address boards always come with the replacement panel (along with other printed circuit boards). See Replacing Plasma Display Panels