Hacks to the RepRap Motherboard v1.1
If you want to run this board off the USB cable without the big power connector do this:
Put a link across two of the mounting holes for that connector (just to the left of A). Solder in a 3.3V regulator (78L33) and a 100uF smoothing capacitor at B. The flat on the regulator and the -ve wire on the capacitor are both towards the bottom of the picture.
Note - if you want access to the RS485 but don't want to use RJ45 connectors you'll find that simple 2.54mm pin headers fit neatly into the connections (see C).
Then put a link as shown at A above between the third pin of the USB TTL input (the red wire on the USB connector) and pin 2 of the ISP connector.
Your board will now be fully powered by the USB cable.