I thought it best to first get things working without the synchronisation and worry about that later.

I desoldered the header sockets (by destroying them) so I could solder leads directly to the board to minimise weight. The first attempt didnt work, the micro kept resetting. Because the power is supplied via wipers on the slip rings, maybe the powersupply isnt clean enough so I added a capacitor to provide a constant supply, worked great.

Now the MCU was attached to the original power supply I had to disconnect the power to reprogram the MCU via usb, this was going to be a pain so used a double pole power switch to totally isolate the MCU when the power is switched off.