Abstract: A power supply includes circuitry implementing a self-testing method in which the power supply is first disconnected from its source and the system which it supplies. The power supply testing method then applies an external power source to the supply, insures that the power supply planar is disconnected from the application system and applies a simulated full load to the power supply output. The power supply output voltages are then tested for compliance with predetermined specifications and a test result signal is given to the user. The power supply is then shut off and available for re-connection to the application system.