The Rowan Elettronica C290S is a unidirectional three‑phase variable speed drive (4.5–7.5 kW) that uses over‑dimensioned controlled diodes for power conversion and offers silent, constant torque operation when coupled to ROWAN motors. Common failure points in this class include diode or MOSFET burnout from over‑voltage/over‑current events, overheating of the internal heat sink, input voltage mismatch (220–380 VAC), and loss of external speed‑control signals. First‑check diagnostics: verify 220–380 VAC supply continuity and correct phase balance; inspect the drive’s thermal pad and heatsink for excessive temperature or oil leakage; check the status LEDs or diagnostic port for fault codes, and confirm that the potentiometer or external control signal is within spec.[oss-gpt-20b]