The Trumpf BUM60S‑4 is a mono‑power servo amplifier rated for 3 × 400/460 VAC input and 3 × –390/450 VAC, 3 × 4 A output with a discharge time of <1 min. Common failure modes in this class include phase‑to‑phase transformer winding insulation breakdown, over‑current protection trips due to motor overload or shorted windings, and fault in the integrated power MOSFET array leading to overheating or open‑circuit behavior. Initial checks should verify that the input voltage is within spec and that all three phases are present; inspect the output phase currents for imbalance or excessive values; then examine the main PCB for burnt components, damaged capacitors, or melted solder joints, and review any error codes displayed on the unit’s diagnostic panel.[oss-gpt-20b]