This is typically due to video crosstalk in your SCART table. While you watch a SCART input, the same interface in the TV still outputs the programme from the analogue tuner or some other source. It then bleeds over to the picture you are actually watching.

Your options:

• get a better quality, well shielded SCART cable (easier said than done)
• tune the TV to some analogue channel that doesn't transmit anything before switching to the SCART input - the "snowy" picture will still bleed over in the cable, but is usually very difficult to notice
• snip the wire from pin 19 in the SCART connector at the TV end of the cable. This will disable the bleeding signal from the cable (and mark the cable, as it won't work in the other direction anymore, and will drive you nuts searching for the problem some time later!)

This sounds very much like you are using a cheaper scart lead that only has an overall screen and not individual screens on the video leads.

When you switch to scart input, there is still an off air signal going out of the scart socket for recording purposes. If there is only an overall screening on the cable, then the video information going out of the scart socket interacts with the video signal coming into the scart socket.

Try selecting an unused UHF TV channel before selecting the scart input to see if the problem still exists.

Ron

Yes, a cheap SCART is in use

I tuned the tv to a spare channel with no reception. This eliminated the 'lines' problem but the picture was a little snowy.

Then SCART wire 19 was snipped and that's worked. The signal/picture is now much improved.

Thanks for the good advice langleyav & tournedos.