The Bycan RB‑14/28‑25P is an aircraft ramp power supply that delivers a filtered 14 V or 28 V DC output up to 25 A for avionics and actuator testing. Common failure points in this class include degraded rectifier diodes, overheating of the internal transformer winding, and wear on the voltage regulation ICs which can cause output sag or over‑voltage spikes. First‑check diagnostics should verify that the input AC is within spec (120/230 V ±10 %) and that the unit’s fuse and circuit breakers are intact; then perform a continuity test across the rectifier bridge and measure the DC output with the selector set to 14 V and 28 V while monitoring for ripple or temperature rise. Finally, inspect the heat sink and fan (if present) for dust buildup and ensure proper airflow.[oss-gpt-20b]