S-Video Output To Tube TV - Horizontal Lines?

[eight_ball]

TV: SonyKV32FS120 Trinitron WEGA (NTSC)

This isn't really mediaportal related, but I figured someone here must have an answer with all the people using TVs.

I'm using an s-video output on my geforce 7800 GS OC card to my Sony Tube TV. The only problem is that I get faint, slow moving, horizontal lines scrolling from the bottom of the screen up. It's subtle, but extremely annoying.

These are the things I've done to try and remedy the situation:

I've tried several different s-video cables of varying qualities.

I tried a geforce 5600 card using the s-video output.

I tried changing the resolution and timing settings (although I don't really know how to configure the timing settings to match my TV)

I read a post else where suggesting that it was EMI interference and so I bought some ferrite chokes and put them on each end of the s-video cable to remove the possible interference.

I can still see the lines!

Any help with this issue would be greatly appreciated!

[eight_ball]

The problem ended up being the CATV cable being plugged into the back of the TV.

To make a long and complicated story short - CATV usually uses a floating ground and the TV and PC uses a solid ground.

Having the two different grounds plugged into the TV creates a ground loop - thus creating "Video Hum" - which are the slow moving horizontal lines on the TV.

The solution(s):

unplug the CATV cable from the TV (more of a temporary solution)

or

get a ground loop isolator (isolation transformer) for the CATV cable

or

get a power bar that has a CATV cable grounding feature and make sure your TV is plugged into it as well.


Hope that saves some possible frustration for anybody who has or will have this problem!

More reading on the subject:

Wikipedia: Ground Loops

Wikipedia: Isolation Transformers

A power bar with CATV surge protection