There are so many reasons for this fault to a Plasma screen. If you wish to get more details, check this link.
http://electronicshelponline.blogspot.com/ Selecting the view option, either to
Mosaic
/ Time slide, can be selected by the
drop-down list, at the top left
of the display window, will make surf easy. You can also do a search, by type in the brand name/model
number/IC used, in the search box at the top right of the display window. Screen-shots to defective plasmas are given with illustrations. You can see, and compare it to that of your TVs' and can get an idea, or can reapair it by yourself.