11.2 Troubleshooting the Hardware Box
11.2.9 The video system
Typically, when a computer is having video display errors, the system might boot normally, but there is no video display. Troubleshooting the video display should start outside the computer case. The technician should begin by verifying that the monitor is turned on and plugged into a functional wall outlet or socket. Test the wall socket by plugging in a known good device. For example, plug in an operational radio to double check the wall outlet or socket. After the connection has been verified, check the connections to the computer case. The video cable will be connected to a female DB-9 or a female DB-15 located on the back of the computer case. The picture illustrates a DB-15 connection.

After all the connections have been correctly attached, move inside the computer to troubleshoot the problem. Open the case and verify the video card is properly inserted. It might have to be taken out and reseated to double-check the installation. If the video card is in a PCI slot, install the video card in another slot. Some video cards need to be inserted into a particular PCI slot to work properly.

Note: Some computers will have two video cards. If this is the case, try connecting the video cable to both video cards. If the problem still exists, one of the cards will have to be disabled and the other card will have to be enabled. This usually happens when the video card is integrated into the motherboard. The onboard video card may be auto detected and reinstalled as new hardware on each startup. If these symptoms exist, the onboard video card will be the operational card. Plugging the monitor into the onboard video card can access CMOS setup.

Change the video settings, exit, and save changes. Plug the monitor into the modular video card and start the system.

Video cards can also have problems related to software. Always verify that the latest driver is installed for the video card. Use the disks that came with the card or visit the manufacturer website.

Video Monitor
The problems associated with the video monitor are usually caused by the configurations of the video card. High performing video cards can overload a lower performing monitor. Overloading the monitor can cause damage to the circuitry. If the monitor is being overloaded by the output of the video card, set the monitor to standard VGA settings of 640 by 480 pixels. Troubleshoot the monitor settings if the problem still occurs. If advanced monitor settings are incorrect, they can adversely affect the video display.

Caution: Troubleshooting monitors can be fatal. The Cathode Ray Tube (CRT) contains a capacitor and can store potentially 25,000 volts. This voltage can be stored long after the monitor has been disconnected. Never assume this voltage is not present. Troubleshooting the internal components of a monitor is recommended for experienced technicians only.