SP9006 (Alarm 06) Thermal Sensor Disconnect fault in Fanuc drive

SP9006 (Alarm 06) Thermal Sensor Disconnect fault in Fanuc drive

Description

SP9006 indicates a broken circuit in the temperature monitoring system of the Spindle Motor. It is different from an actual overheat (Alarm 01/09). This alarm means the Spindle Amplifier has detected "Infinite Resistance" or "Zero Volts" on the temperature feedback line. The drive knows that even a cold motor should have some resistance, so it concludes the wire is cut or the sensor is unplugged.

Cause

• Unplugged Cable: The feedback connector (JY2 or JYA2) is unplugged at the drive or motor.
• Broken Wire: The specific pins for the thermistor (often pins 10/11 or similar) are broken inside the connector shell due to cable strain.
• Sensor Failure: The thermistor element inside the motor windings has snapped open.

Solution

1. Check Connector: Wiggle the feedback cable at the motor. If the alarm comes and goes, it's a bad crimp.
2. Parameter Bypass (Temporary): In emergency situations, you can sometimes disable the temperature sensor check in the spindle parameters (e.g., set the sensor type to "None" or "0"). Warning: The motor will have no overheat protection.
3. Replace Sensor: If the sensor is accessible (external), replace it. If internal, the motor usually needs rewinding.