DX6i with FrSky Hack Module
Connecting up the DX6i to the FrSky hack module is fairly straightforward, but it took a little while to work out how the 'Trainer Logic' circuit works in the DX6i. There are 4 cables going to the trainer port on the DX6i. The red and black are the power + and - and the yellow cable is PPM in. The fourth orange cable needs to be connected to the power cable in order to get the DX6i to accept the PPM input. When you connect power in this way, the power switch on the fron of the DX6i actually needs to stay in the off position and the on position becomes the off position. This is what I meant about trying to figure out how the 'Trainer Logic' works.
Connecting the Screen
Here is a picture showing the back of the screen with the control board all connected up. As I found out, it's really important to keep the back of the control board well insulated from the back of the screen and I did this using some thick double sided foam. I had to extend the power cables for the screen as they weren't quite long enough to be able to mount the control board otherwise. Having set up the screen using the keypad, I no longer need it, so the only 2 cables going to it are the power cable and composite input.
Next step is to connect up a 6v UBEC to power the DX6i and FrSky hack Module and then wire the switches up to power the screen and receiver. I eventually want to add a diversity receiver system, raspberry Pi and DVR so I have to try and think about it at this stage of the design so that I can try to avoid having loads of unused holes in the box when I add them.