The Fanuc LTD A16B‑1212‑0110‑01 is a dedicated AC power supply (PCB B2) used in CNC and servo control systems, providing regulated output to the main controller board. Common failures on this model include capacitor degradation, overheating of the transformer winding, and failure of the internal rectifier bridge or MOSFET array; these often manifest as voltage sag, audible arcing, or a complete loss of power to the machine. First‑check diagnostics: verify incoming line voltage and polarity, inspect the output rails for correct voltage levels and ripple, and look for visual signs of burnt components or blown fuses on the PCB. If the unit passes electrical tests but still causes errors, review the controller’s error logs for “power supply failure” codes and confirm that the I/P unit (if separate) is functioning correctly.[oss-gpt-20b]