Steps to confirm that power-supply unit is defective1 Disconnect the power cord from the power-supply unit.CAUTION: Ensure that you take adequate safety precautions beforeaccessing the components on your computer. See the removing andreplacing instructions in the service manual for procedure to access thepower-supply unit and its cables.2 Disconnect the power-supply unit cables from the system board.3 Connect the power cord to the power-supply unit.– If the LED is on for 3 seconds and turns off, it indicates that the power-supply unit is functional. Continue with troubleshooting steps for otherdevices.– If the LED does not turn on, it indicates a power-supply unit failure. Replacethe power-supply unit only.Enhanced Pre-Boot System Assessment(ePSA) diagnosticsCAUTION: Use the ePSA diagnostics to test only your computer. Using thisprogram with other computers may cause invalid results or error messages.The ePSA diagnostics (also known as system diagnostics) performs a complete checkof your hardware. The ePSA is embedded with the BIOS and is launched by the BIOSinternally. The embedded system diagnostics provides a set of options for particulardevices or device groups allowing you to:• Run tests automatically or in an interactive mode• Repeat tests• Display or save test results• Run thorough tests to introduce additional test options to provide extrainformation about the failed device(s)• View status messages that inform you if tests are completed successfully• View error messages that inform you of problems encountered during testingNOTE: Some tests for specific devices require user interaction. Alwaysensure that you are present at the computer terminal when the diagnostictests are performed.138
