i just finished building the machine, but the touch probe can’t get a closed loop, and I need some help:
- I have PCB version 2.2 from 2015
- touch probe 3 wires (white, green, red) are properly connected to the PCB
- touch probe has the green LED active
Problem: My PCB has no ground connection to the chassis. the PCB is fixed with 4 nylon screws to the base, and the PCB has no copper traces where the screws are. hence the touch probe can not establish a ground loop.
in other words, I found plenty of places on the chassis to attach the ground alligator clip to, but the chassis has zero connection to anything on the PCB.
question: where do I connect the ground loop to the PCB in order to get the touch probe working?