Burnt out RAMPS 1.4??? (no replies)

I am now on my 4th RAMPS in 1 week and have no idea what is causing the problem and cannot afford to keep on doing this. It was working fine for a month or so and then the heater failed to heat the extruder. We then pulled the RAMPS off and saw that the bottom track connecting the wire to the MOSFET had burnt out. This then happened on 3 other RAMPS boards as well. On the first board (green in the picture) we attempted to swap out the MOSFET but that had not worked. There was too much damage to the board.

flickr link

The boards are from different suppliers, (2) reprapdiscount, lulzbot and ultibots?.


Bot type + setup
Mandel
Marlin firmware
Jhead extruder
4 stepper motors
Heated build platform
240w power supply
Software: Slic3r & Pronterface

/\/