FANUC α i Series Servo and Spindle System Maintenance Guide

Fan replacement: The internal fan and radiator fan of the amplifier are both vulnerable parts. When replacing, disconnect the power supply first, wait for the DC bus to discharge completely (LED to turn off), and then disassemble the fan unit according to the manual steps. Pay attention to the blowing direction of the fan and the position of the connector buckle.

Battery replacement: The absolute encoder relies on the battery to maintain position data. When the CNC screen flashes "APC" (low battery voltage), it should be replaced within one to two weeks. Replacement must be carried out when the system is powered on and in emergency stop mode to prevent data loss. For motors with backup capacitors (such as the α iS series), replacement within 10 minutes after power failure can avoid returning to the reference point. The battery model must use FANUC designated products, pay attention to polarity, and strictly prohibit mixing old and new batteries or parallel connection of multiple sets of batteries.

Fuse replacement: When the control circuit fuse (usually 3.2A/48V) is blown, it is necessary to first check whether the external 24V power supply is short circuited or whether the communication cable between amplifiers is reversed. When replacing, it is necessary to use fuses of the same specifications and ensure that the circuit board is properly plugged in.

Fault diagnosis and handling

The modern FANUC system provides powerful Smart Trouble Shooting capabilities to help quickly locate problems.

Alarm code reference: When an alarm occurs, first record the alarm number (such as SV0438, SP9012) on the CNC screen and the code displayed on the amplifier LED. The second part of the manual provides a detailed list of alarm codes and corresponding handling methods.

Intelligent diagnostic function (applicable to 30i-B series):

Fault diagnosis guidance: Press the 【 GUIDE 】 soft key on the alarm screen, and the system will start the diagnostic process, automatically analyze possible causes, and provide processing suggestions. Some diagnostic steps may require the operator to answer 'yes/no' to further narrow down the scope.

Fault diagnosis monitor: This function can monitor and record key data such as current, voltage, speed, position deviation, insulation resistance, etc. in real-time at the moment of alarm and multiple sampling cycles before the alarm. By analyzing these historical data, engineers can determine whether the malfunction is accidental interference or permanent damage.

Common troubleshooting examples:

SV0438 (abnormal motor current): may be caused by power line short circuit, motor winding to ground short circuit, or amplifier failure. The diagnostic guidance will suggest disconnecting the motor wires and re powering on for self diagnosis. Based on the self diagnosis results (such as "phase open circuit" or "current control failure"), further locate whether it is a motor/cable problem or an amplifier problem.

SP9012 (DC bus overcurrent): For low-power spindle modules, this alarm may also be accompanied by IPM overheating. When troubleshooting, check whether there is a short circuit in the motor power line, whether the motor insulation is good, and whether the parameter settings are correct (such as motor code).

SV0449 (IPM alarm): Mostly caused by overcurrent or overheating. Diagnostic guidance will check the DC bus voltage, radiator temperature, and power line status, and prompt to check if the motor is overloaded or if the cooling fan is stopped.

Regular maintenance plan

To ensure long-term fault free operation of the system, it is recommended to develop and implement the following periodic maintenance plan:

Regular (semi annual/yearly) assessment criteria for inspection items

Environmental temperature √ 0~55 ℃ inside the electrical cabinet

Humidity, dust √ No condensation, no conductive dust

Cooling fan √ runs smoothly without any abnormal noise

Power supply voltage √ 200V series: 200~240V; 400V series: 400~480V

The status lights √ of each module display a normal ready status

The connector and cable are not loose, there is no heating or discoloration, and the sheath is not cracked

Motor insulation resistance √>10M Ω (500V megohmmeter)

Absolute encoder battery √ voltage normal, no "APC" alarm prompt

Cleaning of heat sink √ No dust, oil stains or blockages