Thank you Señor_2, your written description is written in a way that my blonde locks comprehend.

As for the responses about the battery connection.......this has me nervous! Would I be correct in presuming that if the unit only turns on when I have the key turned to ACC that it is not connected directly to the battery???

Cheers, M

No, not an assumption you want to make.  As an example, do you see your car stereo on without the key in?  No (if it's been wired correctly), it has a Bat+ connection to maintain station memory.  The same with this TV setup, it MAY have a memory saver circuit.  Not saying that it does, just that it's safer to disconnect the battery first.