Pioneer plasma has scrolling (purple and green) horizontal lines due to cable converter connection. Changed cable box and cables - problem is still there. Any help much appreciated.

Run new RG-6 coax cable from the providers network tap to your TV taking care to minimize the number of times you split the incoming signal.

Thanks Optiva - I'll try but it won't be easy. Meanwhile, would a line amplifier solve the problem?

Pioneer plasma has scrolling (purple and green) horizontal lines due to cable converter connection. Changed cable box and cables - problem is still there. Any help much appreciated.

GROUND LOOP - search the forum for more details.