I think it's the scart's fault. Some scart pins may be missing, or the connection with the device and the scart may not be very strong. Try to push the scart as much as you can to the dvd player and tv too.
The Sony DVD is connected with scart on AV1 but when playing the DVD you can see the freeview shadow on the screen. the TV is a Panasonic VIERA TH-50PX8B
Also there is a white dotted line on the top of the screen. I did change the picture size but that only distorts the video.
thank you Blina that's one problem solved. very obvious but i didn't know. check both the tv and the DVD player scart and push them in.
the second problem is not solved its a mystery why there is a dotted white line at the top of the screen.
