Top 5 Error Codes RZ Technicians see on a Fanuc Servo Amplifier

If your machine is equipped with Fanuc Automation components, and your CNC machine suddenly stops working, you probably check the status display on your Fanuc servo amplifier to see what number is displayed.

These numbers are error, fault, or alarm codes. There are 9 possibilities. The drive and amplifier technicians at Repair Zone use these codes to troubleshoot during a repair. When repairing Fanuc amplifiers, our technicians see the same fault codes come up multiple times. Here the top 5 most common error codes found on the status display on C-Series, Fanuc servo amplifiers:

Error Code #1
Overvoltage alarm (HV). If DC voltage of main power supply is abnormally high, overvoltage alarms occurs (HV level: 430V DC). Alarm occurs when regenerative discharge resistor is disconnected. For 200V AC input, main circuit voltage is 283V DC (200 x 1.414). Discharge operation is started at voltage of main circuit voltage plus 60V.

Error Code #3
DC link undervoltage alarm (LVDC). Alarm occurs if DC voltage of main circuit power supply is abnormally low (LVDV level: 120V). *Causes may include power supply voltage (+15V) being 10Vor lower and driver module PCB not inserted normally.

Error Code #8
Overcurrent alarm (HCL). Alarm occurs when abnormally high current flows in main circuit of 1-axis amplifier or in main circuit of L axis of 2-axis amplifier. *Causes may include faulty IC, abnormal PWM signal, faulty motor, and grounded wiring.

Error Code #2
Control power supply undervoltage alarm (LV5V). Alarm occurs if control circuit power supply voltage (+5V) is abnormally low (LV5V level: 4.6VDC).

Error Code #5
Excessive regenerative discharge alarm (DCOH). Alarm occurs when average regenerative discharge energy is too high. *Causes may include operation of thermostat for regenerative discharge resistor or thermostat between (15) and (16) on terminal block T1; this operation results from too frequent acceleration/deceleration operations.