Ok. Got a hold of a multimeter.
So the following two measurements should be made:
- measure between the motor output common terminal the negative side to the spindle controller and see if you get zero ohms
- measure with an ohm meter between the spindle driver case and the Negative side of the DC power coming into the spindle controller.
One question: the spindle controller is powered by 230AC, not DC. From the instructions of the two measurements above, I don't know what you mean with DC power coming into the spindle controller. I am attaching a better picture of the controller and its terminals.
The terminals are the following:
- 0-10V input for automtic control from MACH3
- 3 terminals used by the potentiometer for manually adjusting the speed of the spindle
- two terminals for connecting an emergency switch
- two terminals for spindle/motor control
- two terminals for AC power (i've connected the ground wire of the power cable to the chassis as instructed elsewhere)