The Life Fitness DCMD66 treadmill motor controller board is a 110 V power‑comb style PCB that drives the treadmill’s main motor and manages start/stop and speed ramping via integrated MOSFET drivers and a magnetic speed sensor. Common failure modes include burned or swollen electrolytic capacitors, cracked or open MOSFETs in the H‑bridge, failed voltage regulator ICs (often 78xx series), and damaged input/output traces from repeated power cycling; these faults typically manifest as no motor start, erratic speed changes, or a “power off” error code. First‑check diagnostics: verify that the 110 V supply is present at the board’s input pins, inspect for visual signs of component damage (burn marks, bulging caps), and confirm continuity on the MOSFET driver outputs; then review any stored error codes via the treadmill console to pinpoint the fault source.[oss-gpt-20b]