The large PFC bulk capacitor can hold up to 400V DC long after the AC cord is unplugged. Always use a dedicated discharge resistor tool to safely bleed this charge down to 0V before touching components.
While rare, if this fails, the PSU will not start or will fail under load. 3. Step-by-Step Schematic Troubleshooting Procedure ps42419ha schematic work
Build a low-power environmental logger:
Boosts the rectified AC voltage to a stable 380V–400V DC bus. The large PFC bulk capacitor can hold up
A shorted Schottky diode will pull the voltage down, preventing startup. 4. Necessary Tools for Schematic Work if this fails