[mythtv-users] TV-out interference

[Dave Weaver]

I'm still having a little difficulty with the picture output from my
MythTV box, and wondered if anyone here would have a clue as to what's
going on.

If I connect my PC to my TV, with my aerial cable dirctly into the TV
card, I get a nice clear picture.
However the aerial connection is first passed through either my VCR or
my Sky digibox then I get interference; vertical bands sweeping
right-to-left at about 3 per sec.
I also get exactly the same visual interferencce problem if I don't
connect the aerial, but instead connect the audo-out of my sound card
into my Yamaha amp (If I connect the audio-out to my TV, which is in
turn connected to the amp, there is no interference).

I've no idea what the problem might be (audio/video/electrical isn't my
field at all) - can anyone point me in the right dirction? 

This is so very close to working that I'm pulling my hair out in
frustration.

Many thanks,
Dave.