Video Adapter Troubleshooting

Solving most graphics adapter and monitor problems is fairly simple, although costly, because replacing the adapter or display is the normal procedure. However, before you take this step, be sure that you have exhausted all your other options. One embarrassingly obvious fix to monitor display problems that is often overlooked by many users is to adjust the controls on the monitor, such as the contrast and brightness.

Although most monitors today have a control panel on the front of the unit, other adjustments might be possible as well. Some NEC monitors, for example, have a focus adjustment screw on the left side of the unit. Because the screw is deep inside the case, the only evidence of its existence is a hole in the plastic grillwork on top of it.

To adjust the monitor's focus, you must stick a long-shanked screwdriver about 2'' into the hole and feel around for the screw head. This type of adjustment can save you both an expensive repair bill and the humiliation of being ridiculed by the repair technician.

Always examine the monitor case, documentation, and manufacturer's Web site or other online services for the locations of adjustment controls. A defective or dysfunctional adapter or display usually is replaced as a single unit rather than being repaired.

Except for specialized CAD or graphics workstation–oriented adapters, virtually all of today's adapters cost more to service than to replace, and the documentation required to service the hardware properly is not always available. You usually can't get schematic diagrams, parts lists, wiring diagrams, and other documents for most adapters or monitors.

Also, virtually all adapters now are constructed with surface-mount technology that requires a substantial investment in a rework station before you can remove and replace these components by hand. You can't use a $25 pencil-type soldering iron on these boards!

Servicing monitors is a slightly different proposition. Although a display often is replaced as a whole unit, some displays—particularly 20'' or larger CRTs or most LCD panels—might be cheaper to repair than to replace. If you decide to repair the monitor, your best bet is to either contact the company from which you purchased the display or contact one of the companies that specializes in monitor depot repair.

If your monitor has a 15'' diagonal measurement or less, consider replacing it with a unit that is 17'' or larger because repair costs on small monitors come close to replacement costs and large monitors aren't much more expensive these days.

Depot repair means you send in your display to repair specialists who either fix your particular unit or return an identical unit they have already repaired. This usually is accomplished for a flat-rate fee; in other words, the price is the same no matter what they have done to repair your actual unit.

Because you usually get a different (but identical) unit in return, they can ship out your repaired display immediately on receiving the one you sent in, or even in advance in some cases. This way, you have the least amount of downtime and can receive the repaired display as quickly as possible. In some cases, if your particular monitor is unique or one they don't have in stock, you must wait while they repair your specific unit.

Troubleshooting a failed monitor is relatively simple. If your display goes out, for example, a swap with another monitor can confirm that the display is the problem. If the problem disappears when you change the display, the problem is almost certainly in the original display or the cable; if the problem remains, it is likely in the video adapter or PC itself.

Many of the better quality, late-model monitors have built-in self-diagnostic circuitry. Check your monitor's manual for details. Using this feature, if available, can help you determine whether the problem is really in the monitor, in a cable, or somewhere else in the system. If self diagnostics produce an image onscreen, look to other parts of the video subsystem for your problem.

The monitor cable can sometimes be the source of display problems. A bent pin in the DB-15 connector that plugs into the video adapter can prevent the monitor from displaying images, or it can cause color shifts. Most of the time, you can repair the connector by carefully straightening the bent pin with sharp-nosed pliers.

If the pin breaks off or the connector is otherwise damaged, you can sometimes replace the monitor cable. Some monitor manufacturers use cables that disconnect from the monitor and video adapter, whereas others are permanently connected. Depending on the type of connector the device uses at the monitor end, you might have to contact the manufacturer for a replacement.

If you narrow down the problem to the display, consult the documentation that came with the monitor or call the manufacturer for the location of the nearest factory repair depot. Third-party depot repair service companies are also available that can repair most displays (if they are no longer covered by a warranty); their prices often are much lower than factory service. Check the Vendor List on the DVD for several companies that do depot repair of computer monitors and displays.

For most displays, you are limited to making simple adjustments. For color displays, the adjustments can be quite formidable if you lack experience. Even factory service technicians often lack proper documentation and service information for newer models; they usually exchange your unit for another and repair the defective one later. Never buy a display for which no local factory repair depot is available.

If you have a problem with a display or an adapter, it pays to call the manufacturer, who might know about the problem and make repairs available. Sometimes, when manufacturers encounter numerous problems with a product, they might offer free repair, replacements, or another generous offer that you would never know about if you did not call.

Remember, also, that many of the problems you might encounter with modern video adapters and displays are related to the drivers that control these devices rather than to the hardware. Be sure you have the latest and proper drivers before you attempt to have the hardware repaired; a solution might already be available.

Monitors Troubleshooting


No picture.


If the LED on the front of the monitor is yellow or flashing green, the monitor is in power-saving mode. Move the mouse or press Alt+Tab on the keyboard and wait up to 1 minute to wake up the system if the system is turned on.

If the LED on the front of the monitor is green, the monitor is in normal mode (receiving a signal), but the brightness and contrast are set incorrectly; adjust them.

If no lights are lit on the monitor, check the power and power switch. Check the surge protector or power director to ensure that power is going to the monitor. Replace the power cord with a known-working spare if necessary. Retest. Replace the monitor with a known-working spare to ensure that the monitor is the problem.

Check data cables at the monitor and video card end.


Jittery picture quality.


LCD monitors. Use display-adjustment software or onscreen menus to reduce or eliminate pixel jitter and pixel swim.

All monitors. Check cables for tightness at the video card and the monitor (if removable):

  • Remove the extender cable and retest with the monitor plugged directly into the video card. If the extended cable is bad, replace it.

  • Check the cables for damage; replace as needed.

  • If problems are intermittent, check for interference. (Microwave ovens near monitors can cause severe picture distortion when turned on.)

CRT monitors. Check refresh-rate settings; reduce them until acceptable picture quality is achieved:

  • Use onscreen picture adjustments until an acceptable picture quality is achieved.

  • If problems are intermittent and can be "fixed" by waiting or gently tapping the side of the monitor, the monitor power supply is probably bad or has loose connections internally. Service or replace the monitor.

Video Cards and Drivers Troubleshooting


Display works in DOS but not in Windows.


If you have an acceptable picture quality in MS-DOS mode (system boot) but no picture in Windows, most likely you have an incorrect or corrupted video driver installed in Windows. Boot Windows 9x/Me in Safe Mode (which uses a VGA driver), boot Windows 2000/XP in Enable VGA mode, or install the VGA driver and restart Windows. If Safe Mode or VGA Mode works, get the correct driver for the video card and reinstall.

If you have overclocked your card with a manufacturer-supplied or third-party utility, you might have set the speed too high. Restart the system in Safe Mode, and reset the card to run at its default speed.


Can't replace built-in video card with add-on PCI video card.


Check with the video card and system vendor for a list of acceptable replacement video cards. Try another video card with a different chipset. Check the BIOS or motherboard for jumper or configuration settings to disable built-in video. Place the add-on card in a different PCI slot.


Can't select desired color depth and resolution combination.


Verify that the card is properly identified in Windows and that the card's memory is working properly. Use diagnostic software provided by the video card or chipset maker to test the card's memory. If the hardware is working properly, check for new drivers.


Can't select desired refresh rate.


Verify that the card and monitor are properly identified in Windows. Obtain updated drivers for the card and monitor.