The Accu‑Rite 3x Mill D200 DOM Controller is a three‑axis digital readout and motion control unit used in milling applications. Common failure modes for this model include communication link errors between the controller and servo drives, power supply degradation (especially transformer or filter failures), and intermittent servo motor drive faults that can trigger error codes on the display. First‑check diagnostics should verify the main power supply voltage and continuity to the power entry module, inspect all I/O connectors and cable harnesses for corrosion or loose contacts, and review any recorded error codes or LED status indicators before proceeding with deeper hardware inspection.[oss-gpt-20b]