Symptoms of a Bad Y-Buffer
Modern televisions all use some type of circuit board to control the image that appears on the screen. Plasma TVs, though, are a bit more complicated. The screen you see is actually several layers, including one with ionized gas, that work together to produce the picture. Circuit boards such as the upper and lower Y-buffer manage the process. When the TV starts to fail, knowing more about the boards will help you identify which one needs replacing.
Inside the TV
If you unplug your television and remove the back panel, you will see three circuit boards. On the left are two boards, one on the bottom and one on the top. Running down the side are ribbon strips that connect to the boards and screen. On the right side of the TV is one circuit board. The twin boards on the left are the upper and lower Y-buffers. The one on the right is the Y-main board. Although each board has a job to do, the upper and lower Y-buffers do the same thing but each controls a different part of the screen.
The upper and lower Y-buffer boards control what happens on the screen. The lower board manages the image on the bottom half while the upper board handles the top of section of the screen. This is a key to knowing when one of these boards goes out. What you see on your screen is not actually one picture, it is two halves. When one half goes dark or becomes distorted, you know one of your Y-buffer boards has gone bad. If the bottom is faulty, the bottom of the screen is affected.
The Y-main board helps to control the image as well. It works to regulate what is happening between the two buffer boards. When the problem on the screen is not specific to one section of the image, the issue is not the Y-buffer boards but the Y-main. This would include no picture at all on the screen. With a bad Y-main, you might see distortion that runs vertically or horizontally across the entire picture.
There are a few things to consider if you want to change out any of the boards yourself. The job is not complex; it is something you could do at home with just a screwdriver. To access the board, make sure to keep the television vertical. You do not want to lie a plasma TV down to remove the back panel; doing so will damage the complex screen. Never remove the back panel on your TV without unplugging the unit first.