@Cris_Hawkins Chris, was the board working when you took it out? In particular did it fire the laser all the time?
Edit: never mind I figured it out … very strange circuit…
@donkjr FYI - I knew from the beginning that the stock K40 was user hostile, so I took all the electronics out before I ever plugged it in. I am upgrading almost everything and have not fired the laser at all, nor have I even filled it with water. The board you now have has only been powered on the bench just once, but never attached to the laser.
I have a C3D mini and external stepper drivers. I purchased an analog meter and potentiometer, and will add a voltmeter across the pot like you have. I am building a new exhaust fan from a small a/c motor I have and a HVAC fan from my car (it really blows). For cooling I am using a radiator intended for computer cooling.
The project is about 60% finished. When I finish, I will get to fire up the laser for the first time.