751

Check the two-digit alarm code on the spindle amplifier 7-segment LED display. Record the exact code (e.g., 11, 25, 50, 64, 86, etc.).

Navigate to SYSTEM > DIAGNOSIS > [SPINDLE] screen and check diagnostic numbers D0100-D0117 for spindle load meter, actual speed, and motor current values to confirm abnormal conditions.

Verify spindle amplifier parameters match motor nameplate: Check parameters 4001 (motor type), 4002 (motor serial number), 4020-4026 (rated voltage, current, speed, poles) in SYSTEM > PARAM > [SPINDLE] screen.

Incorrect motor parameters can cause immediate amplifier trips and motor damage. Always verify against motor nameplate data.

If AL-11 (overcurrent): Check for mechanical binding, seized bearings, or tool crash damage. If AL-25/26 (overvoltage): Inspect regenerative resistor and discharge circuit. If AL-50/64 (encoder): Check encoder cable, battery, and connector X5 on amplifier.

Check spindle amplifier LED for AL-50 (serial pulse coder alarm), AL-64 (position error excess), AL-65 (serial encoder data error), or AL-86 (serial encoder battery low/disconnected).

Inspect encoder cable routing from spindle motor to amplifier connector X5 (αi series) or JD1A (βi series). Check for pinching, cuts, contamination, or loose connectors. Measure cable continuity if damage is suspected.

Perform encoder cable checks with CNC power OFF and amplifier DC link discharged (wait 5 minutes). High voltage may be present.

If AL-86 displayed: Replace encoder backup battery (typically CR17335SE-R or A98L-0031-0025 for αi spindle motors). Check diagnostic D0101 for encoder battery voltage status (should be >3.0V).

Check parameter 4022 (encoder type) and parameter 4023 (encoder pulses per revolution) match actual encoder specification. Mismatch causes position error and AL-64 alarm.

Check spindle amplifier LED for AL-10 (motor overheat thermistor trip) or AL-27 (amplifier module overheat). Verify cooling fan operation on both spindle motor and amplifier heat sink.

Inspect spindle motor cooling fan connector and verify 200VAC or 24VDC supply (depending on fan type). Check for blocked air intake vents or accumulated debris on motor housing and amplifier heat sink fins.

Check diagnostic D0105 (spindle load meter percentage) in DIAGNOSIS screen. Sustained load >80% may indicate excessive cutting load, worn bearings, or improper gear oil level causing increased friction and heat.

Allow motor to cool for 30+ minutes. Reset alarm and monitor temperature rise. If AL-10 repeats immediately, test thermistor resistance at motor connector (should be ~100-500Ω at room temperature). Replace motor if thermistor is shorted or open.

Do not bypass or disable motor thermistor protection. Continued operation without thermal protection can cause permanent motor winding damage.