The HSD RTU500 is a 6‑axis CNC controller and servo drive unit used in Biesse Rover routers, integrating motion control, power conversion, and I/O for spindle and tool management. Common failure modes for this class of equipment include overheating of the drive module, capacitor degradation on the power board, loss of communication with the host PC or PLC, and worn mechanical contacts in the servo motor drivers. First‑check diagnostics: verify that the unit receives its rated input voltage and that all fuses and circuit breakers are intact; inspect the drive board for burn marks, bulging capacitors, or loose solder joints; and review any error codes displayed on the HSD interface or logged by the host system to pinpoint a specific fault.[oss-gpt-20b]