I have not had to do this for many years now...
Typically a TV needs to be instructed to accept signals from various sources
AV1
AV2
Analogue aerial processing (ATV)
Digital aerial signal processing (DTV)
etc...
There are 8 choices on my TV - selected by pressing a button with a logo of a circle pierced by an arrow.
It's a manual selection at the TV itself - if the Video machine plugs into AV1 for instance - you tell the TV to process the signals coming from the AV1 input...
Peccavi
November 2010