Aerobics Inc. WO‑1221 is a treadmill control circuit board that manages motor drives, speed regulation, and safety interlocks in commercial fitness equipment. Common failure modes on this class of boards include burnt or cracked power MOSFETs, degraded voltage regulator ICs, and failing opto‑coupler isolation stages; these often manifest as loss of motor drive, erratic speed changes, or fault codes related to over‑temperature or under‑voltage conditions. First‑check diagnostics: verify the 12 V/24 V supply rails with a multimeter, inspect for visible burn marks or swollen electrolytic capacitors on the board, and review any diagnostic LED patterns or error code displays that the treadmill’s firmware outputs.[oss-gpt-20b]