Messages

1

General Mach Discussion / Re: Help with noise problem

« on: February 14, 2017, 08:03:12 AM »

Hi Tweakie,

I´m connecting the cable shield to the XLR connector and this screwed into the metal case acting as a ground point. Shields are connected only at one end. Would this create ground loops?

Sketch would be:

Breakout board--------------------------->XLR FEMALE- METAL CASE (all shields here) - XLR MALE --------------------->Stepper/limit

How can I identify ground loops?

2

General Mach Discussion / Help with noise problem

« on: February 14, 2017, 07:14:48 AM »

Hi,

Trying to get some help here with a noise problem I´m having on my homebuilt 8 x 4 cnc machine.

Machine is up and running at the moment, no issues and smooth path without input signals for limits but as soon as these are connected the Y axis gains steps when the VFD it´s on.

The machine runs on nema 34 3:1 reduction, with leadshine drivers and ZP5A breakout board. All the electronics are on a metal case (including VFD), running shielded cable to a XLR connector on the case and shielded from there to steppers, and all the shields to a common star ground (metal case and from there to earth ground).

I can run wires from the breakout board to the XLR connector and run the machine correctly as long as the XLR is not in contact with the case. As soon as the XLR connector (with the sield connected to it) is in contact with the metal case and therefore with the star ground, the Y axis gains steps.

I´m fairly confident it´s a noise problem but not sure how to deal with it....any help will be appreciated!

Jordi