A CNC milling machine with Fanuc 3M CNC control, there is abnormal noise on the  X and Y axes, and the Z axis vibrates irregularly while rapid traverse, it is worst especially when the spindle is on also.

Check carefully that it should be related to public power supply parts of the servo system, but measured the working voltages of each axis driver and CNC system, they are ok.

Then check the wave form of input power with the oscilloscope, the input AC voltage wave form of the servo drive is abnormal, which caused by the input resistance of the servo drive, the resistance value has turn to be too big, change it then the machine resumed.