4. Video Adapter Problems
Before assuming the monitor to be faulty, it is worthwhile substituting it with another in order to establish that the video card of the PC is working. Normally such faults as intermittent assortment of odd characters, perhaps some flashing in vivid colours on the screen are indicative of a video card fault.
If the problem appears to be related to mode changing, e.g. form VGA to Super VGA, this may well be due to malfunctioning logic circuitry, relays or solid-state switches, which are best left alone unless the repairer is prepared to spend some considerable time to effect the repair. Many problems arise from inappropriate configuration of the video card. It is often forgotten that many monitors are not designed to operate at high resolutions and high vertical and horizontal frequencies. Using monitors of modest specifications in excess of their design limits will display out-of-sync images possible together with audible buzzing. Persistently overdriving monitors in this way can lead to physical damage of the monitor's circuitry. This phenomenon can be checked by temporarily resetting the PC's display to the standard VGA setting of 640 by 480 pixels.