Yes 2 solutions,

Turn the TV off, then call the source by pressing the AV button before the Source.

Or add V.SETUP to your LIST button. To mute the picture, go to V.SETUP, then press GO, go to PICTURE with the list putton, then press GO, then press the Volume UP and Volume Down button at the same time, like when you mute the sound.

p. 

Me again...

The first solution really turns the tube off, while the second displays a black picture... 

Thanks for the suggestions. Regarding the first, I am assuming that AV must be added to the Beo4 list. I've done this, but the source is the TV (AppleTV connected via AV2 expander) so the picture turns on even if I press AV prior to selecting the source.

I'm certainly trying to stop the tube activating when the speakers are used for music.

It works with mine, but there are several MX7000 models with significantly different software. 

Do you press GO after displaying AV?

It may also depend if the TV is option 1 or option 2.  

It does not work on mine , and yes, I do press Go after AV.

I do not understand what you mean by "TV is Option 1 or Option 2". The TV is not part of a Beolink system, just a standalone TV that has an AppleTV connected to it via an AV2 Expander.

Try and set your TV to Option 2 otherwise it would not react to remote control signals set to the Audio master (like pressing CD or an audio source, or pressing AV and then a video source).

Success!

Thank you so much for your detailed reply. Being an ML novice, I have never understood the Option settings on the Beo4 and have just ignored them.

I now have iTunes streaming audio coming through the speakers of my Beovision MX7000 via the AppleTV, and the picture tube is well and truly off! It's easy when you know how!

Thanks again.

Marcus