I am a noob to all this so please bear with me if my question is stupid. I have bought an endurance 8w laser to affix to my C beam machine. I am using the Spark Concepts CNC pro V3 board. My laser has three wires two clearly the power supply which has to be 12v about 4 - 5 A and a small white wire which I take it is PWM control from the board. If I understand correctly the board requires a ground connection for PWM to work. As I will be using a separate bench power source to get the 12v power supply where do I get the negative return to the board from or do I misunderstand what is required. Sorry but all the help files from endurance are going over my head, any help appreciated thanks !