The idea is to use as much as possible from the original Avant (or BV3) chasis.

From some experiments with beosystem 2 (mk 1,2 and 3) I know that the software is clever enough to figure out what's connected and behave accordingly. The beosystem 2 (and Beovision 5) are very very very similar to the Avant DVD RF. I assume that if you remove the deflection board it will behave as a beosystem.

If that doesn't work I think it's possible to trick the Avant into working without the high energy boards. 

tc0fh:

From some experiments with beosystem 2 (mk 1,2 and 3) I know that the software is clever enough to figure out what's connected and behave accordingly. The beosystem 2 (and Beovision 5) are very very very similar to the Avant DVD RF. I assume that if you remove the deflection board it will behave as a beosystem.

Only the mk3 RF DVD has the same software (latest)16.3 as the system 2/BV5 mk2 and higher.

Don't forget that the chassis switches itself off if there is any fault in the deflection/powersupply. Removing these will result in no startup.

I know (knowledgeable/capable) people who did this experiment years ago. They ended up by removing the tube and deflection and mounted only the deflection on the back of the chassis.

I think it shuts down because of the power supply overload signal from the deflection board or the feedback signals to the TDA9162 on the decoder board.

Have you seen the text strings in the beosystem software eprom?