Fanuc Spindle Alarm 750 and Servo Alarm SV5136

If these alarms occur upon startup, usually the LED indicators on the power module, spindle amplifier, and servo amplifier are all off. Please check whether the CX1A connector of the power module (PSM) has a 200V input. If the 200V input is normal, replace the control board of the PSM power module.

Common Troubleshooting for FANUC Systems with No Alarm Display

Alarm 1750

This alarm occurs in a serial spindle system when the spindle servo module fails to reach a normal startup state during power-on. Use diagnostic function No. 409 to check the specific alarm status and determine the cause of the fault.

SV5136 Alarm

If the SV5136 alarm occurs:

1. Check whether the control power supply (24V) for each servo amplifier (SVM) is normal and whether the LED is lit. If the LED is off but the 24V input is normal, the servo amplifier is considered faulty.

2. If the LED is on, check whether the lower optical port of the FSSB fiber connectors COP10A and COP10B is emitting light. If there is no light emission, the amplifier may be faulty.

3. Check for faults in the FSSB fiber optic cable connecting the servo amplifier and the system axis control card.

    

   (To check: shine a flashlight into one end of the fiber cable. If both optical ports on the other end emit light, the cable is working; otherwise, it is faulty.)

4. Confirm whether any parameters have been changed. Restore the machine to its original parameters.

SV5136 (FSSB: Insufficient Number of Amplifiers)

Troubleshooting Method for SV5136

Cause of the Alarm:

The number of servo amplifiers recognized on the FSSB is insufficient relative to the number of controlled axes.

Alarm Message: FSSB: Insufficient Number of Amplifiers

Troubleshooting Approach:

1. FSSB Setting Screen:

    

   When the alarm occurs, display the amplifier setting screen in the FSSB configuration. This screen shows only the servo amplifiers recognized by the FSSB.

2. Fiber Optic Cable or Amplifier Faults:

    

   The connection between the last recognized amplifier and the next one may be poor. Alternatively, one of the amplifiers at either end of the cable may be faulty. Also, confirm the amplifier’s power supply.

3. Abnormal Servo Amplifier Power Supply:

    

   An internal power abnormality in the servo amplifier can also trigger this alarm. Aside from a drop in amplifier control voltage, for example, if the +5V from the pulse encoder cable is grounded, a power fault will occur.

4. Axis Control Card:

    

   The axis control card on the CNC side may be defective.