The Icon PB‑121 (part #130857) is the main power‑management board for Pro‑Form/Health‑Rider treadmills, converting mains input to the regulated voltages that drive the motor controller and display electronics. Common failure modes on this class of boards include burnt capacitors or electrolytic failures, shorted regulator ICs, and damaged protection diodes, often presenting as no power to the treadmill or intermittent shutdowns. First‑check steps: verify 120 VAC input with a multimeter, inspect the board for visual signs of component damage (burn marks, bulging caps), and test the output rails against the specification data sheet; if these are within spec, proceed to check the motor controller’s input signals and any error codes displayed on the treadmill console.[oss-gpt-20b]