99 Chapter 4Hardware Diagnostic TestingThis section provides a more detailed approach to identifying a hardware problem and locating its source.CAUTION: Turn off devices before disconnecting cables:CAUTION: Before disconnecting any peripheral cables from the system, turn off the system and any externalperipheral devices. Failure to do so can cause permanent damage to the system and/or the peripheraldevices.1. Turn off the system and all external peripheral devices. Disconnect each device from the system, exceptfor the keyboard and the video monitor.2. Make sure the system power cord is plugged into a properly grounded AC outlet.3. Make sure your video display monitor and keyboard are correctly connected to the system. Turn on thevideo monitor. Set its brightness and contrast controls to at least two thirds of their maximum ranges (seethe documentation supplied with your video display monitor).4. If the operating system normally loads from the hard disk drive, make sure there is no diskette in drive Aand no CD-ROM disk in the CD-ROM drive.5. If the power LED does light, attempt to boot from a floppy diskette or from a CD-ROM disk.6. Turn on the system. If the power LED does not light, see "Power Light Does Not Light."Verifying Proper Operation of Key System LightsAs POST determines the system configuration, it tests for the presence of each mass storage device installedin the system. As each device is checked, its activity light should turn on briefly. Check for the following:T Does the diskette drive activity light turn on briefly? If not, see "Diskette Drive Activity Light DoesNot Light."T If system LEDs are illuminated, see "LED Information" for a description of the light and steps totake to correct the problem.Confirming Loading of the Operating SystemOnce the system boots up, the operating system prompt appears on the screen. The prompt varies accordingto the operating system. If the operating system prompt does not appear, see "No Characters Appear onScreen"
