I have a TV linked to the main room TV but when I want to switch on the TV to watch the STB connected to the main room TV, it won't turn on. It will only turn on if the main room TV is also on. 

Is it a problem with the connection or the source setting itself in the main room?

I think it all depends on how the STB is connected.

Are you using the RF device from B&O to get your link room support ?

So free to air works with the Beovision in standby mode ? As in the old analogue TV as well as any new digital free to air ? 

But the STB does not ?

How is the STB connected to the Beovision ?

As I did not set it up myself I'm not quite sure the answer to your questions, but I know there is a RF device in place. We did not set up the free analog TV on the link TV, and it already has its own built in DVB-T module so digital free to air works fine independently of the main room TV. The STB is connected to one of the AV sources on the back of the main room BV. So only when the main room BV is switched on, I can access the STB connected to the main room BV, but if it is switched off, the link TV wouldn't even switch on if I wanted to watch the STB. 

Oasis:

The STB is connected to one of the AV sources on the back of the main room BV

I have lost my set-up (got rid of the old crap cheap tubes) so I can't verify the behaviour, but it sort of makes sense that main BV has to be active at one level

Did the behaviour change or was it always so ?

Oasis:

I have a TV linked to the main room TV but when I want to switch on the TV to watch the STB connected to the main room TV, it won't turn on. It will only turn on if the main room TV is also on. 

Is it a problem with the connection or the source setting itself in the main room?

Hi,

If you want serious answer...., Can you begin to tell us what you have??

If the main tv for example is a newer one,the reason could be that you have energy saving on in the menus, if so the masterlink module on tv is off and not react on command from link room until tv is on

/Tompa