The FANUC LTD AO6B‑6072‑H322#0003 ES3Z00027 B spindle drive is a high‑power spindle inverter module used to control motor speed and torque in CNC machines. Common failure points for this class of drives include overheating of the IGBT or MOSFET array, insulation breakdown on the power stage, and degradation of the input/output protection circuitry; these can manifest as sudden shutdowns, overcurrent trips, or erratic spindle behavior. Initial diagnostics should verify that the supply voltage is within spec and that all input signals (speed setpoint, torque mode, fault status) are clean and properly referenced; then inspect the drive board for burn marks, cracked solder joints, or swollen electrolytic capacitors. Finally, review any stored error codes from the machine controller to pinpoint whether a motor, encoder, or power stage fault is indicated.[oss-gpt-20b]