On Tuesday, September 9, 2014 5:03:17 PM UTC-4, wrote:
Guys ; That is a plasma TV, there is no backlight.


In addition, any partial loss of backlight would shutdown the whole array in a global dimming unit, and even a locally dimmed backlight wouldn't have a sharp line of demarcation as the OP describes.

I wonder if he shouldn't carefully inspect the ribbon cables.