I am running a home brew 3d printer using the Arduino MEGA 2560 board and 1.4 RAMPS. The problem being that the digital pin 8 which powers the heated bed is on all the time so when I start the printer the table immediately begins to heat without reference to the board. Is this a hardware issue or is there something in the firmware? I have tried various firmware but nothing makes any difference. Any ideas out there? thanks all.