I've updated the board with a new function, it's now compatible with an external controller !
It's almost plug and play, you have to remove the tuner connector and replace it with this mini din8 controller connector for japanese controller.
I've put a little 3D printed ring to make it looks likes just you can see below.
The little half rounded PCB is used to block the connector in place on the shell.
Some solder is needed on the connector and the little PCB, when is place you'll need to melt a little bit the solder and the connector is well fixed to the shell.
This new board is
30€ 35€ (connector more expensive now and time consuming) instead of the 20€ for the one without external controller mod.