I recently downsized my CNC router and relocated the controller underneath the router table to save space. However, I encountered a problem after the rebuild. When I have MACH 3 displayed on the computer screen and start the spindle, the screen goes blank. If I start the CNC running and then start the spindle at the inverter controller, the screen flashes. I have already disconnected Mach 3 from the spindle and inverter, but the issue persists. All my cables are shielded and grounded at one end, and I am using an old Windows XP computer. The spindle is water-cooled and controlled with a 2.2KW VFD Inverter. Could this be due to interference, and if so, how can I fix it?

Make sure your AC earth and DC ground are NOT on the same bus.
Does your screen remain illuminated but blank or does it go black?

Thanks For replying Oliver, My screen will go black all together, I did try an external earth between the VFD Inverter and the CNC which did not help, I will now to back to check the earths. There is a possibility I have done this "mixed the DC and AC earths" with me trying to make the wiring as clean as possible, I should get back to it this coming weekend, My thanks again, and I will let you know how I get on.

Noise can also be coupled through the AC supply wiring. In addition to noise, a motor start up can cause a momentary voltage drop. Separate feeds from the breaker/fuse box might help. Experiment by using an extension lead to connect the control electronics to an outlet on a different circuit breaker.