Zimmer Sono 3 is an electro‑ultrasound therapy generator used in physical‑therapy units; it supplies high‑frequency acoustic energy via a piezoelectric transducer and includes temperature, power‑output, and safety monitoring circuits. Common failure modes reported for similar medical ultrasound generators include board-level component burn‑outs (capacitors or MOSFETs), overheating of the transducer driver, loss of signal from the control microcontroller, and faulty power‑input fuses. First‑check diagnostics: verify mains voltage and input fuse integrity; inspect the main PCB for burn marks or swollen electrolytic capacitors; confirm that the output power meter reads within spec when a dummy load is connected; review any error codes displayed on the unit’s LCD or transmitted via its diagnostic port.[oss-gpt-20b]