Hello,

On all the plasma tvs there are control boards on the lower part of the screen that control the vertical images. If one of the chips on one of the boards fail, have a bad connection, or no ground it will result in a thick black line down the screen.

IF YOU HAVE A SOLID BLACK LINE RUNNING VERTICALLY THEN YOU HAVE A FAULTY MATRIX INVERTER. IF CENTRAL THE MAIN VERTICAL INVERTER NEEDS CHANGED. LEFT = LEFT VERTICAL INVERTER RIGHT=RIGHT.........

ANOTHER WAY TO GET THIS FAULT IS WORN OR DAMAGED RIBBON/PLASTIC GOING FROM THE SCREEN MATRIX TO THE INVERTER
Good luck and take care in handling it ........