920

Check the servo amplifier LED display on each axis module (1-4) for a flashing alarm code. Record the specific 4xx alarm number displayed (e.g., 400, 401, 410, 414, etc.).

Navigate to DIAGNOSIS screen and check diagnostics 300-303 (for axes 1-4 respectively) which display servo alarm status, or check diagnostics 400-403 for detailed servo amplifier status codes.

Cross-reference the specific 4xx alarm code with the servo amplifier manual for your amplifier series (αi series for 0i/30i/31i/32i, or βi series for older systems) to determine exact fault condition.

After identifying and resolving the specific 4xx alarm condition, press RESET to clear alarm 920. If alarm persists, check for multiple axis faults or parameter issues.

Check DIAGNOSIS screen numbers 300-303 for position deviation values during alarm occurrence. Excessive deviation (>parameter 1826 setting) triggers alarm 414 with 920.

Do not manually move axes if mechanical damage or collision is suspected. Inspect for bent components first.

Verify servo load meter values in DIAGNOSIS 300-303 or through servo monitor (SYSTEM > DIAGNOSIS > SERVO). Load values consistently above 80% indicate mechanical binding or improper servo tuning parameters 1825, 1827, 1828.

Manually rotate each suspect axis motor by hand with servo OFF to detect mechanical binding, bearing failure, or ballscrew damage. Check for smooth motion throughout entire axis travel.

Ensure servo power is OFF and EMERGENCY STOP is active before manual axis movement.

If mechanical system is free, verify servo parameters 1825 (position loop gain), 1826 (error detection threshold), and 2020-2023 (axis-specific rapid traverse rate) are set correctly per machine specifications.

Check servo amplifier LED for alarm 400 (encoder pulse error), 401 (encoder cable disconnection), or 402 (encoder battery low). Verify encoder cable connections at motor and amplifier are secure with no visible damage.

Navigate to DIAGNOSIS > POSITION and verify encoder feedback pulses are updating smoothly when axis is manually jogged. Erratic or frozen values indicate encoder or cable failure.

Measure encoder cable continuity and shield grounding. Check parameter 1815 (encoder type) and 1820 (encoder pulses per revolution) match the installed encoder specifications, typically 2000-4000 ppr for αi motors.

If encoder cable and parameters are correct, check DIAGNOSIS 351-354 for encoder overheat alarm. Encoder internal failure requires motor or encoder head replacement with proper re-referencing procedure per parameter 1815 setting.

After encoder replacement, absolute position data is lost. Execute return to reference point sequence and verify parameter 1850 (reference point return settings) before operation.