Thanks very much for the info and the link to your very nice video (though it is too bad you didn't have a chance to document the internal view). I've never hooked up FPV electronics before. Are you powering the VTx using just the smaller ribbon cable (3-wire) from the upgrade board kit? DJI has been unclear about whether the output from the discrete GCU includes V+ or not. However this is moot once the Phantom upgrade board is installed.
The VTx I have has a 5-pin cable input with V+ and Ground for 'battery in' and then Video in, V+ out (to power the FPV camera which is not needed with GoPro on the Zen), and Camera Ground. My question is whether I need to hook up both grounds to the ground from the Phantom cable, or whether I simply use V+, Ground, and Video in coming straight from the smaller ribbon cable.
Steve