MONITOR & SERVICING

MONITOR & SERVICING

Your monitor provides the link between you and your computer. Although you can possibly get rid of your printer, disk drives, and expansion cards, you cannot sacrifice the monitor. Without it, you would be operating blind; you could not see the results of your calculations or the mistyped words on-screen.

The video subsystem of a PC consists of two main components:

·        Monitor (or video display)

·        Video adapter (also called the video card or graphics card)

This chapter explores the range of available PC-compatible video adapters and the displays that work with them.

Monitors

The monitor is, of course, the display located on top of, near, or inside your computer. Like any computer device, a monitor requires a source of input. The signals that run to your monitor come from video circuitry inside or plugged into your computer. Some computers such as those that use the low profile (LPX) or new low profile (NLX) motherboard form factor usually contain this circuitry on the motherboard. Most systems, though, use Baby-AT or ATX style motherboards and normally incorporate the video on a separate circuit board that is plugged into an expansion or bus slot. The expansion cards that produce video signals are called video cards, video adapters, or graphics cards. Whether the video circuit is built into the motherboard or on a separate card, the circuitry operates the same way and uses generally the same components.

Display Technologies

A monitor may use one of several display technologies. By far the most popular is cathode ray tube (CRT) technology, the same technology used in television sets. CRTs consist of a vacuum tube enclosed in glass. One end of the tube contains an electron gun; the other end contains a screen with a phosphorous coating.

When heated, the electron gun emits a stream of high-speed electrons that are attracted to the other end of the tube. Along the way, a focus control and deflection coil steers the beam to a specific point on the phosphorous screen. When struck by the beam, the phosphor glows. This light is what you see when you watch TV or your computer screen.

The phosphor chemical has a quality called persistence, which indicates how long this glow will remain on-screen. You should have a good match between persistence and scanning frequency so that the image has less flicker (if the persistence is too low) and no ghosts (if the persistence is too high).

The electron beam moves very quickly, sweeping the screen from left to right in lines from top to bottom, in a pattern called a raster. The horizontal scan rate refers to the speed at which the electron beam moves across the screen.

During its sweep, the beam strikes the phosphor wherever an image should appear on- screen. The beam also varies by intensity in order to produce different levels of brightness. Because the glow fades almost immediately, the electron beam must continue to sweep the screen to maintain an image a practice called redrawing or refreshing the screen.

Most displays have an ideal refresh rate (also called a vertical scan frequency) of about 70 hertz (Hz), meaning that the screen is refreshed 70 times a second. Low refresh rates cause the screen to flicker, contributing to eyestrain. The higher the refresh rates the better for your eyes.

Some monitors have a fixed refresh rate. Other monitors may support a range of frequencies; this support provides built-in compatibility with future video standards. A monitor that supports many video standards is called a multiple-frequency monitor. Most monitors today are multiple- frequency monitors, which means that they support operation with a variety of popular video signal standards. Different vendors call their multiple-frequency monitors by different names, including multisync, multifrequency, multiscan, autosynchronous, and autotracking.

Phosphor-based screens come in two styles curved and flat. The typical display screen is curved, meaning that it bulges outward from the middle of the screen. This design is consistent with the vast majority of CRT designs (the same as the tube in your television set).

The traditional screen is curved both vertically and horizontally. Some models use the Trinitron design, which is curved only horizontally and is flat vertically. Many people prefer this flatter screen because it results in less glare and a higher-quality, more accurate image. The disadvantage is that the technology required to produce flat-screen displays is more expensive, resulting in higher prices for the monitors.

Alternative display designs are available. Borrowing technology from laptop manufacturers, some companies provide LCD (liquid-crystal display) displays. LCD’s have low-glare flat screens and low power requirements (5 watts versus nearly 100 watts for an ordinary monitor). The color quality of an active-matrix LCD panel actually exceeds that of most CRT displays. At this point, however, LCD screens usually are more limited in resolution than typical CRTs and are much more expensive; for example, a 12.1-inch screen costs several thousand dollars. There are three basic LCD choices: passive-matrix monochrome, passive-matrix color, and active-matrix color. The passive-matrix designs are also available in single- and dual-scan versions.

In a LCD, a polarizing filter creates two separate light waves. In a color LCD, there is an additional filter that has three cells per each pixel one each for displaying red, green, and blue.

The light wave passes through a liquid-crystal cell, with each color segment having its own cell. The liquid crystals are rod-shaped molecules that flow like a liquid. They enable light to pass straight through, but an electrical charge alters their orientation, as well as the orientation of light passing through them. Although monochrome LCD’s do not have color filters, they can have multiple cells per pixel for controlling shades of gray.

In a passive-matrix LCD, each cell is controlled by electrical charges transmitted by transistors according to row and column positions on the screen's edge. As the cell reacts to the pulsing charge, it twists the light wave, with stronger charges twisting the light wave more. Supertwist refers to the orientation of the liquid crystals, comparing on mode to off mode the greater the twist, the higher the contrast.

Charges in passive-matrix LCD’s are pulsed, so the displays lack the brilliance of active-matrix, which provides a constant charge to each cell. To increase the brilliance, some vendors have turned to a new technique called double-scan LCD, which splits passive-matrix screens into a top half and bottom half, cutting the time between each pulse. Besides increasing the brightness, dual-scan designs also increase the response time or speed of the display, making this type more usable for video or other applications where the displayed information changes rapidly.

In an active-matrix LCD, each cell has its own transistor to charge it and twist the light wave. This provides a brighter image than passive-matrix displays because the cell can maintain a constant, rather than momentary, charge. However, active-matrix technology uses more energy than passive-matrix. With a dedicated transistor for every cell, active-matrix displays are more difficult and expensive to produce.

In both active and passive-matrix LCD’s, the second polarizing filter controls how much light passes through each cell. Cells twist the wavelength of light to closely match the filter's allowable wavelength. The more light that passes through the filter at each cell, the brighter the pixel.

Monochrome LCD’s achieve gray scales (up to 64) by varying the brightness of a cell or dithering cells in an on-and-off pattern. Color LCD’s, on the other hand, dither the three-color cells and control their brilliance to achieve different colors on the screen. Double-scan passive-matrix LCD’s have recently gained in popularity because they approach the quality of active-matrix displays but do not cost much more to produce than other passive-matrix displays.

The big problem with active-matrix LCD’s is that the manufacturing yields are low, forcing higher prices. This means that many of the panels produced have more than a certain maximum number of failed transistors. The resulting low yields limit the production capacity and incur higher prices.

In the past, several hot CRTs were needed to light a LCD screen, but portable computer manufacturers now use a single tube the size of a cigarette. Light emitted from a tube gets spread evenly across an entire display using fiber-optic technology.

Thanks to supertwist and triple-supertwist LCD’s, today's screens enable you to see the screen clearly from more angles with better contrast and lighting. To improve readability, especially in dim light, some laptops include backlighting or edgelighting (also called sidelighting). Backlit screens provide light from a panel behind the LCD. Edgelit screens get their light from the small fluorescent tubes mounted along the sides of the screen. Some older laptops excluded such lighting systems to lengthen battery life. Most modern laptops enable you to run the backlight at a reduced power setting that dims the display but allows for longer battery life.

The best color displays are active-matrix or thin-film transistor (TFT) panels, in which each pixel is controlled by three transistors (for red, green, and blue). Active-matrix-screen refreshes and redraws are immediate and accurate, with much less ghosting and blurring than in passive-matrix LCDs (which control pixels via rows and columns of transistors along the edges of the screen). Active-matrix displays are also much brighter and can easily be read at an angle.

An alternative to LCD screens is gas-plasma technology, typically known for its black and orange screens in some of the older Toshiba notebook computers. Some companies are incorporating gas-plasma technology for desktop screens and possibly color high-definition television (HDTV) flat-panel screens.

Monitor Resolution

Resolution is the amount of detail that a monitor can render. This quantity is expressed in the number of horizontal and vertical picture elements, or pixels, contained in the screen. The greater the number of pixels, the more detailed the images. The resolution required depends on the application. Character-based applications (such as word processing) require little resolution, whereas graphics-intensive applications (such as desktop publishing and Windows software) require a great deal.

There are several standard resolutions available in PC graphics adapters. The following table lists the standard resolutions used in PC video adapters and the term used to commonly describe them:

Resolution	Acronym	Standard Designation
640x480	VGA	Video Graphics Array
800x600	SVGA	Super VGA
1,024x768	XGA	extended Graphics Array
1,280x1,024	UVGA	Ultra VGA

In a monochrome monitor, the picture element is a screen phosphor, but in a color monitor, the picture element is a phosphor triad. This difference raises another consideration called dot pitch, which applies only to color monitors. Dot pitch is the distance, in millimeters, between phosphor triads. Screens with a small dot pitch contain less distance between the phosphor triads; as a result, the picture elements are closer together, producing a sharper picture. Conversely, screens with a large dot pitch tend to produce images that are less clear.

Another consideration of resolution is the dot pitch of the monitor. Smaller pitch values allow the monitor to produce sharper images. The original IBM PC color monitor had a dot pitch of 0.43mm, which is considered to be poor by almost any standard. The state-of-the-art displays marketed today have a dot pitch of 0.25mm or less.

Energy and Safety

A properly selected monitor can save energy. Many PC manufacturers are trying to meet the Environmental Protection Agency's Energy Star requirements. Any PC-and-monitor combination that consumes less than 60 watts (30 watts apiece) during idle periods can use the Energy Star logo. Some research shows that such "green" PCs can save each user about $70 per year in electricity costs.

Monitors, being one of the most power-hungry computer components, can contribute to those savings. Perhaps the best-known energy-saving standard for monitors is VESA's Display Power-Management Signaling (DPMS) spec, which defines the signals that a computer sends to a monitor to indicate idle times. The computer or video card decides when to send these signals.

If you buy a DPMS monitor, you can take advantage of energy savings without remodeling your entire system. If you do not have a DPMS-compatible video adapter, some cards can be upgraded to DPMS with a software utility typically available at no cost. Similarly, some energy-saving monitors include software that works with almost any graphics card to supply DPMS signals.

Another trend in green monitor design is to minimize the user's exposure to potentially harmful electromagnetic fields. Several medical studies indicate that these electromagnetic emissions may cause health problems, such as miscarriages, birth defects, and cancer. The risk may be low, but if you spend a third of your day (or more) in front of a computer monitor, that risk is increased.

The concern is that VLF (very low frequency) and ELF (extremely low frequency) emissions might affect the body. These two emissions come in two forms: electric and magnetic. Some research indicates that ELF magnetic emissions are more threatening than VLF emissions, because they interact with the natural electric activity of body cells. Monitors are not the only culprits; significant ELF emissions also come from electric blankets and power lines.

These two frequencies are covered by the new Swedish monitor-emission standard called SWEDAC, named after the Swedish regulatory agency. In many European countries, government agencies and businesses buy only low-emission monitors. The degree to which emissions are reduced varies from monitor to monitor. The Swedish government's MPR I standard, who dates back to 1987, is the least restrictive. MPR II, established in 1990, is significantly stronger (adding maximums for ELF as well as VLF emissions) and is the level that you will most likely find in low-emission monitors today.

A more stringent 1992 standard called TCO further tightens the MPR II requirements. In addition, it is a more broad-based environmental standard that includes power-saving requirements and emission limits. Nanao is one of the few manufacturers currently offering monitors that meet the TCO standard.

A low-emission monitor costs about $20 to $100 more than similar regular-emission monitors. When you shop for a low-emission monitor, don't just ask for a low-emission monitor; also find out whether the monitor limits specific types of emission. Use as your guideline the three electromagnetic-emission standards described in this section.

If you decide not to buy a low-emission monitor, you can take other steps to protect yourself. The most important is to stay at arm's length (about 28 inches) from the front of your monitor. When you move a couple of feet away, ELF magnetic emission levels usually drop to those of a typical office with fluorescent lights. Likewise, monitor emissions are weakest at the front of a monitor, so stay at least 3 feet from the sides and backs of nearby monitors and 5 feet from any photocopiers, which are also strong sources of ELF.

Electromagnetic emissions should not be your only concern; you also should be concerned about screen glare. In fact, some antiglare screens not only reduce eyestrain but also cut ELF and VLF emissions.

VGA Adapters and Displays

When IBM introduced the PS/2 systems on April 2, 1987, it also introduced the Video Graphics Array (VGA) display. On that day, in fact, IBM also introduced the lower-resolution multicolor Graphics Array (MCGA) and higher-resolution 8514 adapters. The MCGA and 8514 adapters did not become popular standards like the VGA, and both were discontinued.

Digital Vs Analog Signals.

Unlike earlier video standards, which are digital, the VGA is an analog system. Why are displays going from digital to analog when most other electronic systems are going digital? Compact-disc players (digital) have replaced most turntables (analog), and newer VCRs and camcorders have digital picture storage for smooth slow motion and freeze-frame capability. With a digital television set, you can watch several channels on a single screen by splitting the screen or placing a picture within another picture.

Most personal-computer displays introduced before the PS/2 are digital. This type of display generates different colors by firing the RGB electron beams in on-or-off mode. You can display up to eight colors (2 to the third power). In the IBM displays and adapters, another signal intensity doubles the number of color combinations from 8 to 16 by displaying each color at one of two intensity levels. This digital display is easy to manufacture and offers simplicity with consistent color combinations from system to system. The real drawback of the digital display system is the limited number of possible colors.

In the PS/2 systems, IBM went to an analog display circuit. Analog display work like the digital displays that use RGB electron beams to construct various colors, but each color in the analog display system can be displayed at varying levels of intensity 64 levels, in the case of the VGA. This versatility provides 262,144 possible colors (64³). For realistic computer graphics, color often is more important than high resolution, because the human eye perceives a picture that has more colors as being more realistic. IBM moved graphics into analog form to enhance the color capabilities.

Video Graphics Array (VGA)

PS/2 systems contain the primary display adapter circuits on the motherboard. The circuits, or VGA, are implemented by a single custom VLSI chip designed and manufactured by IBM. To adapt this new graphics standard to the earlier systems, IBM introduced the PS/2 Display Adapter. Also called a VGA card, this adapter contains the complete VGA circuit on a full-length adapter board with an 8-bit interface. IBM has since discontinued its VGA card, but many third-party units are available.

The VGA BIOS (Basic Input/Output System) is the control software residing in the system ROM for controlling VGA circuits. With the BIOS, software can initiate commands and functions without having to manipulate the VGA directly. Programs become somewhat hardware-independent and can call a consistent set of commands and functions built into the system's ROM-control software.

Future implementations of the VGA will be different in hardware but will respond to the same BIOS calls and functions. New features will be added as a superset of the existing functions. The VGA, therefore, will be compatible with the graphics and text BIOS functions that were built into the PC systems from the beginning. The VGA can run almost any software that originally was written for the MDA, CGA, or EGA.

In a perfect world, software programmers would write to the BIOS interface rather than directly to the hardware and would promote software interchanges between different types of hardware. More frequently, however, programmers want the software to perform better, so they write the programs to control the hardware directly. As a result, these programmers achieve higher-performance applications that are dependent on the hardware for which they were first written.

When bypassing the BIOS, a programmer must ensure that the hardware is 100 percent compatible with the standard so that software written to a standard piece of hardware runs on the system. Just because a manufacturer claims this register level of compatibility does not mean that the product is 100 percent compatible or that all software runs as it would on a true IBM VGA. Most manufacturers have "cloned" the VGA system at the register level, which means that even applications that write directly to the video registers will function correctly. Also, the VGA circuits themselves emulate the older adapters even to the register level and have an amazing level of compatibility with these earlier standards. This compatibility makes the VGA a truly universal standard.

The VGA displays up to 256 colors on screen, from a palette of 262,144 (256K) colors. Because the VGA outputs an analog signal, you must have a monitor that accepts an analog input.

VGA displays come not only in color but also in monochrome VGA models, using color summing. With color summing, 64 gray shades are displayed instead of colors; the translation is performed in the ROM BIOS. The summing routine is initiated if the BIOS detect the monochrome display when the system is booted. This routine uses a formula that takes the desired color and rewrites the formula to involve all three-color guns, producing varying intensities of gray. The color that would be displayed, for example, is converted to 30 percent red plus 59 percent green plus 11 percent blue to achieve the desired gray. Users who prefer a monochrome display, therefore, can execute color-based applications.

Super VGA (SVGA)

When IBM's XGA and 8514/A video cards were introduced, competing manufacturers chose not to clone these incremental improvements on VGA. Instead, they began producing lower-cost adapters that offered even higher resolutions. These video cards fall into a category loosely known as Super VGA (SVGA).

SVGA provides capabilities that surpass those offered by the VGA adapter. Unlike the display adapters discussed so far, SVGA refers not to a card that meets a particular specification but to a group of cards that have different capabilities.

For example, one card may offer several resolutions (such as 800x600 and 1,024x768) that are greater than those achieved with a regular VGA, whereas another card may offer the same or even greater resolutions but also provide more color choices at each resolution. These cards have different capabilities; nonetheless, both are classified as SVGA.

The SVGA cards look much like their VGA counterparts. They have the same connectors, including the feature adapter shown in Figure 10.6.

Because the technical specifications from different SVGA vendors vary tremendously, it is impossible to provide a definitive technical overview in this book. The pinouts for the standard VGA and SVGA video card connector are shown in the following table:

Pin	Function	Direction
1	Red	Out
2	Green	Out
3	Blue	Out
4	Monitor ID 2	In
5	Digital Ground (monitor self-test)	--
6	Red Analog Ground	--
7	Green Analog Ground	--
8	Blue Analog Ground	--
9	Key (Plugged Hole)	--
10	Sync Ground	--
11	Monitor ID 0	In
12	Monitor ID 1	In
13	Horizontal Sync	Out
14	Vertical Sync	Out
15	Monitor ID 3	In

Video Memory

A video card relies on memory in drawing your screen. You can often select how much memory you want on your video card--for example, 256K, 512K, 1M, 2M, 4M, 6M, or 8M are common choices today. Most cards today come with at least 1M and usually have 2M. Adding more memory does not speed up your video card; instead, it enables the card to generate more colors and/or higher resolutions.

The amount of memory needed by a video adapter to display a particular resolution and color depth is a mathematical equation. There has to be a memory location used to display every dot (or pixel) on the screen, and the number of total dots is determined by the resolution. For example 1,024x768 resolution represents 786,432 dots on the screen.

If you were to display that resolution with only two colors, you would only need 1 bit to represent each dot. If the bit were a 0, the dot would be black, and if it were a 1, the dot would be white. If you used 4 bits to control each dot, you could display 16 colors, since there are 16 combinations possible with a four-digit binary number (2 to the 4th power equals 16). If you multiplied the number of dots times the number of bits required to represent each dot, you have the amount of memory required to display that resolution. Here is how the calculation would work:

1,024x768	= 786,432 dots x 4 bits per dot
	= 3,145,728 bits
	= 393,216 bytes
	= 384K

As you can see, to display only 16 colors at 1,024x768 resolution would require exactly 384K of RAM on the video card. Because most cards would normally suppor0t only memory amounts of 256K, 512K, 1M, 2M, or 4M, you would have to install 512K to run that resolution. Upping the color depth to 8 bits per pixel results in 256 possible colors, and a memory requirement of 786,432 bytes or 768K. Again, since no video card can install that exact amount, you would have to install an actual 1M on the video card.

In order to use the higher resolution modes and greater numbers of colors in SVGA cards, such cards will need more memory than the 256K found on a standard VGA adapter.

From this table, you can see that a video adapter with 2M can display 65,536 colors in 1,024x768-resolution mode, but for a true color (16.8M colors) display, you would need to upgrade to 4M. In most cases, unless you are doing photo-realistic editing requiring 24-bit (16.8M color) support, 2M are all you need on your video adapter.

A 24-bit (or true-color) video card can display photographic images by using 16.8 million colors. If you spend a lot of time working with graphics, you may want to invest in a 24-bit video card with up to 4M of RAM. Many of the cards today can easily handle 24-bit color, but you may need to upgrade from 2M to 4M of RAM to get that capability in the higher-resolution modes.

Another issue with respect to memory on the graphics adapter is how wide the access is between the graphics chipset and the memory on the adapter. The graphics chipset is usually a single large chip on the card that contains virtually all of the adapter's functions. It is wired directly to the memory on the card through a local bus. Most of the high-end adapters use an internal 64-bit or even 128-bit wide memory bus. This jargon is confusing, because this does not refer to the kind of bus slot the card plugs into. In other words, when you read about a 64-bit graphics adapter, it is really a 32-bit (PCI or VLB) card that has a 64-bit local memory bus on the card itself.

Improving Video Speed

Many efforts have been made recently to improve the speed of video adapters because of the complexity and sheer data of the high-resolution displays used by today's software. The improvements in video speed are occurring along three fronts:

·        Processor

·        RAM

·        Bus

The combination of these three is reducing the video bottleneck caused by the demands of graphical user interface software, such as Microsoft Windows.

Video Output Devices:

When video technology was first introduced, it was based upon television. There is a difference between the signals a television uses and the signals used by a computer. In the United States, the National Television System Committee (NTSC) established color TV standards in 1953. Some countries, such as Japan, followed this standard. Many countries in Europe developed more sophisticated standards, including Phase Alternate Line (PAL) and SEquential Couleur Avec Memoire (SECAM).

A video-output (or VGA-to-NTSC) adapter enables you to show computer screens on a TV set or record them onto videotape for easy distribution. These products fall into two categories: those with genlocking (which enables the board to synchronize signals from multiple video sources or video with PC graphics) and those without. Genlocking provides the signal stability needed to obtain adequate results when recording to tape but is not necessary for simply using a video display.

VGA-to-NTSC converters come as both internal boards and external boxes that you can port along with your laptop-based presentation. These latter devices do not replace your VGA adapter but instead connect to your video adapter via an external cable that works with any type of VGA card. In addition to VGA input and output ports, a video-output board has a video output interface for S-Video and composite video.

VGA-to-TV converters support the standard NTSC television format and may also support the European PAL format. The resolution shown on a TV set or recorded on videotape is often limited to straight VGA at 640x480 pixels. Such boards may contain an "anti-flicker" circuit to help stabilize the picture, which often suffers from a case of the jitters in VGA-to-TV products.

Advanced Power Management (APM)

APM is a specification created by Microsoft and Intel that allows the system BIOS to manage the power consumption of the system and various system devices.

For displays, power management is implemented by a standard called DPMS (Display Power Management Signalling). This standard defines a method for signalling the monitor to enter into the various APM modes. The basis of the DPMS standard is the condition of the synchronization signals being sent to the display. By altering these signals, a DPMS-compatible monitor can be forced into the various APM modes.

The defined monitor states in DPMS are as follows:

·        On. Refers to the state of the display when it is in full operation.

·        Stand-By. Defines an optional operating state of minimal power reduction with the shortest recovery time.

·        Suspend. Refers to a level of power management in which substantial power reduction is achieved by the display. The display can have a longer recovery time from this state than from the Stand-By State.

·        Off. Indicates that the display is consuming the lowest level of power and is non-operational. Recovery from this state may optionally require the user to manually power on the monitor.

Adapter and Display Troubleshooting

Solving most graphics adapter and monitor problems is fairly simple, although costly, because replacing the adapter or display is the usual procedure. A defective or dysfunctional adapter or display usually is replaced as a single unit, rather than repaired. Most of today's cards cost more to service than to replace, and the documentation required servicing the adapters or displays properly is not always available. You cannot get schematic diagrams, parts lists, wiring diagrams, and so on for most of the adapters or monitors. Many 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.

Servicing monitors is a slightly different proposition. Although a display often is replaced as a whole unit, many displays are simply too expensive to replace. Your best bet is to either contact the company from which you purchased the display, or to contact one of the companies that specializes in monitor depot repair.

Depot repair means that you would send in your display to depot repair specialists who would either fix your particular unit or return an identical unit they have already repaired. This is normally 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 will 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 down time and can receive a repaired display as quickly as possible. In some cases, if your particular monitor is unique or one they don't have in stock, then you will have to 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, then the problem was almost certainly in the original display; if the problem remains, then it is likely in the video card or PC itself.

After you narrow down the problem to the display, call the display manufacturer for the location of the nearest factory repair depot. There are also alternative third-party depot repair service companies that can repair most displays; their prices often are much lower than factory service.

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 adapter, it pays to call the manufacturer who might know about the problem and make repairs available, as occurred with the IBM 8513 display. Large numbers of the IBM 8513 color displays were manufactured with components whose values change over time and may exhibit text or graphics out of focus. I discovered that IBM replaced these displays at no cost when focusing is a problem. As the 8513 have been out of production for some time, replacements are no longer available.

Remember that most of the problems you have with modern video adapters and displays will be related to the drivers that control these devices rather than the hardware itself. Contact the manufacturers to ensure that you have the latest and proper drivers; there may be a solution that you are unaware of.

Troubleshooting a Monitor

When a monitor goes bad you are usually stuck with replacing it. If you are lucky you can find someone to repair it. The number one thing to remember is never to try and fix it from the inside you even when the monitor has been unplugged from the wall for a while. A lethal charge will remain in the monitor for a good amount of time.

Now what is some thing's to look at when troubleshooting monitor problems? Most of these are fairly common and easily fixed. Again not from the inside though.

Most of the time your problems are with the cabling, or interference from other devices.

Interference is caused by

Ø      Uneven Electrical Currents

Ø      Interference From speakers, fans, and telephones

Ø      Bad connection through cabling

Ø      Cabling overlength

Electrical currents can cause some real strange problems as with the rest of the computer. You may already know what a culprit surge protectors or even the power supply of the computer can be. If you suspect that your power supply or surge protector is causing the problems simply plug the monitor into the wall separately. Now in many offices that share power hungry devices on the same circuit you can run into some real problems with your monitor, or system itself. Find another less crowded power source. This can get so hairy you might need to call an electrician to look up more power to the home or office.

Another way to remedy this is to purchase (UPS). Uninterruptible Power Supply, this will take up the slack in the line. The UPS can also help out in those power outage times.

Other Symptoms

Interference, can be a funny little problem to have. If you are having interference this is usually to fans, speakers, or anything that produces electromagnetic fields. This can show up in really cheap multimedia speakers on your system. They should be shielded but don't count on it.

The source of the interference is fairly easy to recognize simply because it will warp the screen a little more in one direction than the rest. This means you will need to take something further away from the desktop to cure it.

More Symptoms

Cabling, the cable itself for the monitor can be bad. Not only can these cables have electromagnetic interference like the rest of the monitor but will also distort you signal if interfered with. This is unlikely in most cases since the cable is shielded itself but can happen.

Length, the cable length can cause you a problem should it be to long. Most cable for a monitor are under 5' long and should stay at that. The longer the cable the weaker the signal. If you do have a cable extender make sure it is shielded.