Causes and solutions:

1-       Mechanical transmission problem.

A:  To check if the belt is broken ot not.

2-       Mechanical part is not put into gear.

A:  Put into gear

3-       Power supply 3 phases but only connect 2 phases

A:  Check power connection

4-       CNC controller has no related spindle control signal output.

A:  Use universal meter to check the CNC controller output signal, if there is no control signal output, then need to replace the related IC component or send back for repair.

5-       CNC controller has spindle control output, but the power cables or signal control cable broken or there is open circuit, or some components broken.

A:  Use universal meter to check if there is open circuit of the power and signal control loop between CNC controller and spindle motor, the contacts of the cables are firm or not? AC contactor or DC relay is broken or not? To check if the heat relay is over load or the protective tube is burned or not? From www.CNCmakers.com

6-       CNC controller has no S01, S02, S03 and S04 output signal.

A:  To check the CNC controller and see if there is shifting control signal output, if there is not, then it should CNC controller problem, need to replace IC component or send back for repair.

7-       Spindle motor broken or shorted.

A:  Check the spindle motor and repair.

AC servo spindle & motors

http://www.cncmakers.com/cnc/controllers/Spindle_Motor_Driver/