441

Power cycle the CNC completely (wait 30 seconds after shutdown). Observe if alarm 441 returns immediately at power-on or during axis movement. Immediate recurrence indicates hardware failure rather than transient offset condition.

Navigate to DIAGNOSIS > SERVO screen and check current feedback values for the affected axis (diagnostic numbers 200-203 for analog current, 300-303 for digital servo current). Compare at-rest values against other axes; offset should be near zero (±5-10mA typical).

Check servo amplifier LED status codes. For αi/βi series amplifiers, observe 7-segment display at power-on. Continuous alarm 441 with normal LED sequence indicates internal amplifier fault requiring replacement.

Do not attempt servo tuning adjustments with alarm 441 active - current offset cannot be calibrated via parameters

Replace the servo amplifier module for the affected axis. After replacement, verify parameter 1815#0 (absolute position loss) if using absolute encoders, and perform current offset auto-tuning if available via maintenance function or parameter 1825 (servo setup parameters).

Record amplifier serial number and all axis parameters before replacement for warranty and configuration restoration

Navigate to DIAGNOSIS > SERVO and monitor DC link bus voltage (diagnostic number 380 for PSM series). Verify voltage is stable at 280-320VDC (for 200V class) or 530-600VDC (for 400V class) with less than ±5% fluctuation.

Check power supply module (PSM/PSU) LED indicators. For PSM-series, green LED should be solid. Check for alarm history in PMC > ALARM HISTORY for power supply related alarms (400-series servo alarms often correlate with power issues).

Inspect DC bus capacitors on power supply module for physical bulging or leakage. Check regenerative discharge resistor connections and resistance values. Degraded capacitors cause voltage ripple that affects current sensor accuracy.

Discharge DC bus capacitors using proper procedure before inspection - lethal voltages present up to 10 minutes after shutdown

Verify incoming AC line voltage stability at control cabinet input. Check for voltage sags, phase imbalance (should be within 2% between phases), and verify proper grounding impedance (<0.1 ohm to earth ground).

Inspect motor power cable shielding integrity and verify 360-degree shield termination at both amplifier and motor ends. Check shield continuity with ohmmeter (should be <1 ohm end-to-end).

Verify motor frame ground connection is secure and measures <0.1 ohm to cabinet ground. Check for multiple ground paths that could create ground loops. Ensure encoder cable shield is grounded only at amplifier end, not at motor end.

Check parameter 1020 (motor serial number) and parameter 1021-1024 (motor characteristics) match the actual installed motor. Mismatched parameters can cause incorrect current calculations that appear as offset errors.

Temporarily swap motor power cables with an identical axis (if available) to isolate whether issue is amplifier-based or cable/motor-based. If alarm moves to the other axis, suspect cable or motor; if alarm stays with original axis, confirms amplifier fault.

Perform cable swap only with power OFF and ensure motor parameters are temporarily adjusted for test or restore immediately after