Thanks a lot.
Well, I inspected the board, and there is nothing to be seen, unless it is minute.
However, what takes me aback is that you plug a DVD [or the DSTV cables] to either of the two AV inputs and you get sound but no picture.
The set works fine via the aerial socket.
This must be a very strange and unusual fault.
What should I do next, I wonder?
I'm stuck!
[I also don't have the service diagram, on top of it.]