Please help - what are these lines on my plasma display? (1 Viewer)

[Dan Woodworth]

I recently purchased a Panasonic TH-42PWD3U plasma display. I am having a problem with some sort of interference with the picture. There are several bands of varying widths (very narrow at the top and as wide as about 2" at the bottom at regular intervals with undistorted video in between) running horizontally across the entire screen width. These bands still diplay the picture but have a noticeable pattern of vertical (or actually slightly angled) lines that move slowly across the screen from left to right. They are most noticeable on a black background and less noticeable when the picture is set to the lower contrast "cinema" preset. At first I thought it might be problem with my cable signal (I live in NYC and have digital cable feed/converter from RCN), but now notice that the lines are present with VCR and DVD input signals as well. Could this be some sort of power line problem, a cable problem (I am current using about a 30' run of regular video cable but will soon be installing RGB connectors), or could the plasma unit be defective or set up improperly? I live in a large apartment building in New York City, and am wondering if there could be interference either in the power supply or from outside elements of some sort. Although my wiring runs are behind a wall, they are not particularly near any other electrical or AC cables as far as I can tell.
Any help would be greatly appreciated by this new HTF member!
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[Allan Jayne]

1. Try moving the TV to a different location in the room and also face it in a different direction, at least for experimenting. The subject of interference even with VCR's playing tapes, came up in a forum thread some months ago and the submittor eventually discovered something electronic inside the wall behind the TV causing the interference. It interfered with a circuit used for DVD and VCR playback as opposed to over the air signals.
2. Try hooking things up with shorter cables or different cables. If there is a grounding problem somewhere, this kind of interference can happen. Someimes cables are defective and the coax shield is not properly connected and then the cable picks up lots of interference. Some cables have the shield connected to one plug but not the other, try reversing a cable end for end.
3. Try routing AC power cords further away from video cables. Bands that move slowly across the screen often involve 60 Hz interference, often due to electromagnetic radiation from a power cord.
Other video hints:
http://members.aol.com/ajaynejr/video.htm

 

[CRyan]

Most likely this is a ground-loop problem. Are you using a Line-conditioner? If not, you probably should invest in one. They are worth every penny in my oppinion. They can get rid of all sorts of problems including the banding you are describing.
C. Ryan

 

[Yumbo]

I have the 50" Panasonic.

About 2 months ago, it developed a horizontal line right in the middle of the screen.

looks like a 1" varying band, very evident in light scenes.

looks like burn-in but pattern says otherwise.

any comments?