87More Problem Solving ProceduresThis section provides a more detailed approach to identifying aproblem and locating its source.Preparing the System for Diagnostic TestingCaution: Turn off devices before disconnecting cables:Before disconnecting any peripheral cables from the system, turnoff the system and any external peripheral devices. Failure to doso can cause permanent damage to the system and/or theperipheral devices.1 Turn off the system and all external peripheral devices. Disconnectall of them from the system, except the keyboard and videomonitor.2 Make sure the system power cord is plugged into a properlygrounded AC outlet.3 Make sure your video display monitor and keyboard are correctlyconnected to the system.Turn on the video monitor. Set its brightness and contrast controlsto at least two thirds of their maximum ranges (see thedocumentation 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 A. Otherwise, place adiskette containing the operating system files in drive A.5 Turn on the system. If the power LED does not light, see “PowerLight Does Not Light” on page 89.6 If errors are encountered, power off the system and remove alladd-in cards.Monitoring POSTSee “Power-On Self-Test (POST)” on page 51.Verifying Proper Operation of Key System LightsAs POST determines the system configuration, it tests for the presenceof each mass storage device installed in the system. As each device is
