Lac503p Schematic -

Disconnect the main logic board. Use a 1k-ohm resistor to jump the standby voltage pin to the PS_ON pin. If the power supply is healthy, the remaining 12V and 24V rails should immediately turn on. Conclusion and Safety Warning

Look for the smoothing capacitors on the secondary output rails (12V and 24V). PFC Boost Diode and MOSFETs lac503p schematic