I've just tried connecting a Mega with my RAMPS-FD, and it's not working. I've first flashed updated firmware with the right pin configuration, and it boots all right on its own, but as long as the Mega is connected to a RAMPS-FD, it will not boot. The power LED is on but it never starts the firmware.
I've left JP101 in the IOREF position, having verified that my Mega provides 5V on the IOREF pin. The metallic USB connector also needed some electrical tape, else it would cause shorts.
I've left JP101 in the IOREF position, having verified that my Mega provides 5V on the IOREF pin. The metallic USB connector also needed some electrical tape, else it would cause shorts.