Anyone familiar with AV auto switching on a TV

[mart]

When a TV is connected to a video player/DVD player etc via scart lead(s) why do some televisions not automatically switch via the AV function?

My 'set up' works fine. If my TV is already on and running and I decide to watch a DVD, all I have to do is press the power button on the DVD player and it starts to play.

Someone I know has trouble with theirs and wants me to go over to look at it. I am trying to establish why their TV plays ok, but when they try to use the connected device the screen just displays no signal.

 

[hotponyshoes]

Aside from the components/cables that are not fully compatible..
Some tvs have an option in the menu to enable auto switching although a "no signal" does not sound like a switching issue, sounds like it's already changed to the input but the device is not sending anything out.
Might also be the device is sending a signal that the tv is not capable or set to recive

 

[gaz1]

its normally there wires that dont have the switching wire (cheap scart lead ) they also can be annoying as well

also a bad connection will cause this to also happen

the cheap scart leads are sometimes not long enough or they push the links back into the socket of the scart so fail to connect

 

[mike 109444]

Take a look in the scart plugs on both ends of the cable to see if it is fully populated with pins. As Gaz has said the cheaper leads (thin cable!) don't always have all the signal pins installed.
Look up a pin out for a scart plug/socket and there is a lot going on !

 

[Anguz]

pin 8 needs to be connected to autoswitch

 

[Seadog]

Take a look in the scart plugs on both ends of the cable to see if it is fully populated with pins. As Gaz has said the cheaper leads (thin cable!) don't always have all the signal pins installed.
Look up a pin out for a scart plug/socket and there is a lot going on !

Sometimes they also have all of pins but not a full complement of cable.