059

Check spindle encoder cable connections at both the motor and amplifier ends for loose connectors, damage, or contamination.

Power off the machine before inspecting connections to prevent electrical shock.

Monitor the spindle encoder signals on the diagnostic screen (POSITION > ENCODER or DIAGNOSIS screen) during manual spindle rotation to verify consistent feedback pulses.

Inspect the encoder itself for mechanical damage, bearing wear, or contamination from coolant/debris that may affect signal quality.

Replace the encoder cable if signal degradation is detected, or replace the encoder if mechanical damage is found.

Verify parameter 4077 (spindle gear ratio) matches the actual mechanical configuration of the spindle transmission.

Document original parameter values before making any changes.

Check parameters 5200-5204 (rigid tap control parameters) for correct encoder counts per revolution and synchronization error limits.

Compare current parameters with OEM documentation or backup parameter files to identify discrepancies.

Restore correct parameter values and perform a test rigid tap cycle at reduced feedrate to verify synchronization.

Check the ALARM/DIAGNOSIS screen for concurrent spindle amplifier alarms (SPA-xxx or SPC-xxx alarms) that indicate communication or drive faults.

Verify the optical fiber or serial communication cables between the CNC and spindle amplifier are properly seated and undamaged.

Monitor spindle load meter and actual speed feedback during manual spindle operation to confirm the amplifier is responding correctly to commands.

Power cycle the spindle amplifier or perform a complete system restart to clear transient communication errors, then retest the rigid tap cycle.

Ensure proper shutdown procedure is followed to prevent data loss or additional faults.