On all of my TVs (5 of them), there is what I would call ghost lines - two parallel horizontal lines about 5" or 6" apart that slowly drift up the screen. The cable guy was over recently doing some work on my cable modem connection and I asked him about it. He checked and said there is a slight amount of voltage between the ground shielding and the center "pin" on the coax. And that could cause this. He said its possible one of the outlets on a circuit that also has a TV on it could be wired wrong. Does this sound reasonable? If so, how can I check outlets for correct polarity? Or, is there another explaination?
What could be wrong? Well, you have cable and you are asking the cable guy questions. By outlets I assume you mean the AC outlet. You can buy a circuit tester at Radio Shack or most hardware stores that will tell you if the outlets are wired correctly. It lights up to indicate proper polarity, no ground etc. This is unlikely to cause the problem you are describing. There should be no voltage between center pin and ground/shield. This is likely your culprit. Disconnest the cable and briefly hook up an antenna, even if it is rabbit ears. You are not interested in good reception just to see if the lines are still there. If they aren't get the cable co. to fix the problem or get a satelite system. If they are, your TV needs repair. It has a leaky capacitor