L‑Tec WM‑637C is the main control board used in the PCM‑321 plasma cutter system, handling power regulation, phase control and user interface signals. Common failure points for this class of industrial plasma controller boards include burnt or cracked voltage regulator components, degraded MOSFETs on the high‑current output stage, and corrosion or broken traces around the phase‑control ICs due to repeated thermal cycling. First‑check diagnostics: verify that the board receives the correct input supply voltage (typically 120 VAC/240 VAC converted to the required DC rails), inspect for obvious burn marks or loose solder joints on the power MOSFETs and regulator packages, and read any stored error codes from the cutter’s diagnostic port.[oss-gpt-20b]