Icon PB‑201 is a switched‑mode power supply board used in Icon Pro‑Form treadmills to convert 120 VAC to the regulated DC rails that drive the motor controller and electronics. Common failure modes on this model include electrolytic capacitor leakage or bulging, transformer winding insulation breakdown, rectifier diode bridge arcing, and voltage regulator dropout (often due to a failed IC or overheating). First‑check diagnostics: verify input AC voltage and continuity of the mains feed; inspect for visible burn marks, swollen capacitors, or loose solder joints on the board; measure output DC rails with a multimeter and compare against spec tables. If outputs are out of range, proceed to isolate the regulator section and test individual components (diodes, inductors, ICs) before considering a full board replacement.[oss-gpt-20b]