Truthfully I do not know, but worst case scenario: The solenoid has a protection circuit and you hook the solenoid up backwards, you power the board up and try to fire the marker and notice that the solenoid is not really working that well or at all. solution: plug the solenoid in the other way.
You arent going to hurt the solenoid in either case. If it does have a protection circuit then the diode is simply going to prevent/reduce the current reaching the solenoid.
Last edited by davethewave12321 : 01-31-2016 at 03:20 AM.