5. Troubleshooting Video Interfaces

In the event of an absent screen image, it is more likely that the monitor is at fault than the video interface. If after substitution, the monitor proves to be operational, suspicion falls on the interface and its associated cables.

Checking that the video card is fully seated in its connector and that the motherboard is designed to accommodate the card, is a useful first step in diagnosing a video communication problem. Reseating the card often cures the fault.

An intermittent assortment of unusual characters in vivid colours is a classic sign of electronic problems with the video card. Replacement of the card is the only solution. With the increasing complexity of these cards and the use of ever larger amounts of high speed video RAM, their ability to dissipate large quantities of heat is crucial to long term reliability. To facilitate this, fans and ductings are increasingly used. If these become encrusted with dust or the fan stops working, the electronics will rapidly fail.

Due to the several different interface ports in current use such as the analogue VGA and the digital DVI and HDMI, the interface may be incompatible with the monitor. In the case of dual head interfaces, where there are two or more output ports, the signal could be directed to the wrong connector. The interface driver software can correct this. Where the monitor has several ports, it may be expecting signals from an unused connector. The monitor’s setup will redirect the signal appropriately. If the driver software has not been installed, the interface is likely to operate only in VGA mode. Installing the software, together with any updates, will make available the full range of modes of the interface.

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