For FANUC CNC machine tools, in a system using serial spindles, when the spindle amplifier does not reach the normal starting state when the power is turned on, an alarm 750 will occur, and the spindle serial link will start badly.

The 750 alarm does not occur after the system (including the spindle control unit) has been started. It must happen when the power is turned on and before the system starts. The alarm after system startup is No. 749.

Reasons for the 750 alarm on CNC machine tools:

(1) The serial spindle cable (JA7A-JA7B) is in poor contact, or the spindle amplifier power is turned off.

(2) The display of the spindle amplifier display is not the alarm state of SU-01 or AL-24. When the CNC power supply is turned on, this alarm occurs mainly when the CNC power supply is turned off during the serial spindle operation. Turn off the power of the spindle amplifier and then start it again.

(3) When the second spindle is in the above state, the second spindle is used and some parameters are set.