Newsgroups: sci.engr.television.advanced,alt.video.digital-tv,rec.audio.pro,alt.tv.tech.hdtv,rec.arts.tv
Subject: Re: TV problem - horizontal lines
References: 
[email protected] (Dennis M) writes:

> Does anyone have an idea why very faint horizontal lines, spaced about 7 or
> 8 inches apart and about a quarter of an inch thick, would move slowly up
> the TV screen after a DVD is played? One of the lines is slightly darker,
> followed by a line that's slightly lighter. After a while they eventually
> go away but I'm wondering what causes this. The same problem has happened
> on two different TV's so I don't think it's a defect in the set (or the DVD
> player).

One possible reason for this kind if problems are ground loops. 
More information on ground loops can be found at 
http://www.epanorama.net/documents/groundloop/index.html

Other potential problems:
- magnetic interference nearby coupling to cable or devices
- bad electrical power filtering on equipment (for example 
  capacitors on power supply going bad on old TV)


-- 
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/