137Hardware diagnostic testingThis section provides a more detailed approach to identifying ahardware problem and locating its source.Caution! Before disconnecting any peripheral cables from thesystem, turn off the system and any external peripheral devices.Failure to do so can cause permanent damage to the system and/or the peripheral device.1 Turn off the system and all external peripheral devices. Disconnecteach of device from the system, except for the keyboard and thevideo monitor.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 itsbrightness and contrast controls to at least two thirds of theirmaximum ranges (see the documentation supplied with your videodisplay monitor).4 If the operating system normally loads from the hard disk drive,make sure there is no diskette in the FDD or disc in the opticaldrive.5 If the power indicator does light, attempt to boot from a disketteor disc.6 Turn on the system. If the power indicator does not light, see“Power indicator does not light” on page 138.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 ischecked, its activity light should turn on briefly. Check if the HDDactivity indicator lights briefly? If not, see “HDD activity indicator doesnot light.” on page 139.
