The Sitra Automation VSH6 is a spindle drive module designed for high‑speed finishing heads on CNC milling machines, typically interfacing with an AC servo motor and a machine controller via digital I/O. Common failure points in this class of drives include power supply degradation (over‑voltage or ripple), phase loss or imbalance in the motor windings, overheating of the inverter bridge due to inadequate cooling, and firmware corruption causing abnormal error codes. Initial diagnostics should verify that the drive’s input voltage is within spec, inspect the I/O connectors for loose or corroded contacts, check the temperature of the motor and inverter enclosure, and review any displayed fault codes against the VSH6 service manual.[oss-gpt-20b]