363

Power off the CNC completely. Inspect the encoder cable (serial pulse coder cable) at both the motor connector and the amplifier connector for bent pins, corrosion, loose locking rings, or physical damage.

Ensure LOCK OUT/TAG OUT procedures before opening cabinet or touching connections.

Check encoder cable routing for pinch points, excessive bending near cable carriers, or contact with sharp edges. Measure cable continuity and insulation resistance if damage is suspected.

Reseat both ends of the encoder cable firmly. If using αi series servo with serial pulse coder, verify the proper cable type (A06B-6096-Hxxx series) and shielding integrity.

After reconnecting, power up and check DIAGNOSIS screen > Servo > DGN 300-303 (serial pulse coder status) to verify encoder communication is restored before clearing alarm.

Access DIAGNOSIS screen > Servo > DGN 300 (Position deviation) and DGN 301 (Encoder feedback). If encoder feedback shows erratic values or zero counts when motor shaft is manually rotated (power off), encoder is likely failed.

Only rotate motor shaft manually with power OFF and amplifier disabled.

Check servo amplifier LED display. Flashing LED codes 4, 5, or alternating patterns often indicate encoder communication faults. Refer to amplifier manual (αi series: A, E, or L codes).

If motor is accessible, inspect encoder end cap for coolant/oil ingress, cracks, or seal damage. Contamination inside encoder housing destroys optical disc or Hall sensors.

Replace motor or encoder assembly if hardware fault confirmed. After replacement, execute reference position return (G28) and verify parameters 1815 (serial encoder type), 1825 (encoder gear ratio), and 1826 (encoder position data) match new encoder specifications.

Incorrect encoder parameters after replacement will cause immediate position errors or runaway conditions.

Check servo amplifier power supply voltages. Access DIAGNOSIS screen > Servo > DGN 200-207 (amplifier status). Verify +5V encoder supply is present and stable (typically shown in diagnostics or measure at amplifier test points).

Use isolated measurement equipment. Do not short test points.

Inspect amplifier for visible damage, burned components, or swollen capacitors on the encoder interface circuit board. Check for alarm history (ALARM > HISTORY) showing concurrent amplifier alarms (400-series overcurrent, 300-series encoder alarms).

Check parameter 2020 (encoder output type) matches actual encoder installed. Mismatch between serial/parallel encoder settings causes communication failure. Verify parameter 1815 specifies correct serial encoder model code.

If multiple axes show intermittent 363 alarms, check main cabinet grounding, AC input power quality, and verify servo amplifier bus voltage (DGN 210-212) is stable. Replace amplifier if encoder interface circuitry is confirmed faulty.