SP0002

Navigate to DIAGNOSIS screen and check spindle servo diagnostics: Press SYSTEM > DIAGNOSIS > Select [SP DIAG] or screen 300-399 for spindle. Monitor parameters #305 (spindle load current), #309 (spindle motor speed), and #325 (spindle command speed) during operation to identify deviation.

Check spindle servo parameters: SYSTEM > PARAM > [SP]. Verify parameter 4020-4022 (spindle position loop gain), 4023-4025 (spindle speed loop gain), and 4026-4028 (spindle speed loop integral time constant) match motor specifications in Fanuc spindle motor parameter manual.

Inspect spindle encoder cable connections at motor and amplifier. Check encoder feedback on DIAGNOSIS screen #40E.0-3 (serial spindle encoder data). Replace encoder cable if intermittent signals detected.

Ensure machine is powered off before disconnecting encoder cables to prevent feedback loss alarms.

Manually rotate spindle by hand with amplifier disabled (parameter 3705#0=1 to disable spindle) to check for mechanical binding, bearing seizure, or foreign objects. If resistance detected, inspect spindle bearings and motor coupling.

Tag out machine and follow LOTO procedures before manual spindle rotation.

Check spindle amplifier LED diagnostic codes on the front panel of the α/βi series spindle drive. Refer to Fanuc Spindle Amplifier manual: Solid red LED indicates hardware fault, flashing patterns indicate specific fault codes. Document LED pattern for amplifier replacement.

Access amplifier alarm history: SYSTEM > MAINTENANCE > [ALARM HISTORY] or DIAGNOSIS screen #7 to review spindle amplifier sub-codes and timestamps. Cross-reference sub-alarm codes with Fanuc Spindle Parameter Manual B-65280EN for specific module failures.

Perform spindle amplifier power cycle isolation test: Power down CNC, disconnect spindle motor power cables (U/V/W) at amplifier, power up and observe if SP0002 persists. If alarm clears with motor disconnected, fault is motor-side; if alarm persists, amplifier module is faulty.

Use insulated tools and verify all voltage is discharged from DC bus capacitors (wait 5 minutes minimum) before disconnecting power cables.

Replace spindle amplifier module with Fanuc-certified replacement. After replacement, reload spindle parameters from backup (SYSTEM > PMC > [I/O] > [LOAD]), set parameter 3705#1=1 to initialize spindle, then execute spindle ID detection if using serial spindle (parameter 4009#1=1).

Ensure replacement amplifier module matches original part number and software version to prevent parameter incompatibility.

Check spindle motor insulation resistance: Disconnect motor power cables at amplifier, use 500V megohmmeter to test resistance between each winding phase (U/V/W) to ground. Readings should exceed 10MΩ. Values below 1MΩ indicate winding insulation breakdown requiring motor replacement.

Discharge motor windings to ground before megohmeter testing and ensure personnel are clear of motor.

Verify spindle encoder operation: Navigate to DIAGNOSIS > [SP DIAG] screen #40C (serial pulse coder) or #4010-4013 (separate detector). Manually rotate spindle and verify encoder counts increment/decrement. No change indicates encoder failure.

Inspect spindle motor thermal sensor circuit: Check DIAGNOSIS screen #308 (spindle motor overheat detection). If parameter 4012#0=1 (thermal sensor enabled), verify continuity of thermal relay connections from motor to amplifier CN on SP unit. Open circuit triggers protective faults.