90 Troubleshooting ToolsThe power supply diagnostic LED located on the back of the computerindicates different states of the power supply. To test the power supply, pressthe power supply test switch.• If the power supply diagnostic LED is green, power is available for thepower supply.• If the power supply diagnostic LED is off:– The power supply is not receiving power — Ensure that the mainpower cable is connected to the system.– The power supply is not working — This issue occurs either due to abad power supply or a device attached to the power supply.To resolve the issue, contact Dell (See "Contacting Dell" on page 141).Beep CodesYour computer may emit a series of beeps during start up. The series of beepsis called a beep code and can be used to help identify a problem with yourcomputer.If your computer emits a series of beeps during start-up:1 Write down the beep code.2 Run the Dell Diagnostics to identify the cause (see "Dell Diagnostics" onpage 95).
