Plasma televisions work by electrically charging ions in plasma to create a picture. This process produces more heat and uses more electricity than standard tube television technology. As it ages, the television may begin to flicker due to overheating, picture degradation or screen problems.
Check the television's fan to see if it is working properly. A plasma TV should contain a cooling system. These televisions produce a lot of heat. Thus, most problems are caused by a failed cooling system.
Leaving your plasma television on for long periods while displaying a static image can cause "burn in." This is a phenomenon in which the image burns itself onto the screen and is always visible. It can also be caused by leaving the television on the same channel, with a logo at the bottom of the screen. Over time this can cause flickering on your screen as well.
Check your plasma for cracks or breaks in the screen. These can cause pixels to burn out and appear to be flickering. Each pixel consists of three sub-pixels containing the colours red, blue and green. If one of these sub-pixels is burnt out, the screen will flicker.