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Last updated on 24 July 2007

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Analog and Digital CRT computer monitors

Introduction

Both analog (analogue) and digital CRT monitors are available, and, as with LCD monitors, you can purchase CRT monitors that have both analog and digital ports.

A 17" CRT or LCD monitor is the minimum a computer should have nowadays.

The size of the screen in inches measures its diagonal length from the top corner to the bottom corner on the opposite side of the screen.

Because some of the screen is not visible (is hidden by the casing) on a CRT monitor, a 15" LCD monitor is the equivalent of a 17" CRT monitor, and a 17" LCD monitor is the equivalent of a 19" CRT monitor, etc. With most CRT monitors an inch or more of the screen is hidden by the case. So, a typical 15" CRT monitor will only have a visible diagonal screen measurement of 14", etc. But all of the screen of an LCD monitor is visible.

You can buy CRT and LCD TFT monitors with built-in speakers and a microphone, but the sound quality if often poor.

Remember that the larger a CRT monitor is, the more power it consumes. A 21-inch monitor will consume about 50% more power than a 15-inch monitor. Over your monitor's useful life, you could probably buy a new 15" monitor with the power savings of using a 15" instead of a 21" monitor. (Page 1 of this article deals with LCD TFT monitors.)

Web pages are often designed for a screen resolution of 800X600 or 480,000 pixels of information.

While some 14" monitors can be set to this resolution, the ideal setting is for one is 640x480, or only 307,200 pixels of information. Thus, if a monitor with a resolution of 640x480 accesses a web page designed for a resolution of 800x600, quite a bit of the information will not be displayed in one go. You will have to use the scroll bars to access it.

Unless a page using a 800x600 resolution is coded to appear centered on the screen, there will be a large white space on the right hand side of the screen if the screen is set to a higher resolution of, say, 1024x768, because the higher the screen resolution, the more information the screen can display in one go.

That is why some ATI video cards come with a Virtual Desktop facility, which enables 14" monitors to display 800X600 worth of information at a screen resolution of 640x480. This is done by moving the cursor to the sides of the screen whereupon the extra space is accessed by shifting the perspective.

The horizontal and vertical scroll bars appear whenever a browser opens a window and a web page is loaded. When using a web page designed for an 800x600 resolution appears on a screen set via Windows to show that resolution, it should not be necessary to use the horizontal scroll bar to view any of the information.

The monitor screen is made up of pixels, each of which has an amount of RAM memory devoted to it. If the RAM devoted to each pixel is 8 bits (1 byte) and the screen resolution is 640X480 or 307,200 pixels, then 307,200 bytes of RAM are needed to display 256 colours.

There are 8 bits to 1 byte of memory.

High Color uses 16 bits or 2 bytes per pixel and displays over 64,000 colours.

True Color uses 24 bits (3 bytes), or 32 bits (4 bytes) to display over 16 million colours.

In each case, the amount of RAM the video card requires can be calculated when it is operating in 2D mode.

Outdated ISA video cards can only operate in 2D mode. PCI video cards can also operate in 2D only, but most new PCI cards can operate in both 2 and 3D.

However, when a video card is operating in 3D mode it requires several large buffers. That is why a video card, attached to a 15" monitor, operating in 2D mode to run business applications, can easily get by with only 2MB of RAM, while video cards used for gaming and intensive graphics applications are now being manufactured with 16, 32, and 64MB of RAM.

Therefore, it is a waste of time having a video card with more than 4MB of RAM if it is only going to be used to run business applications and access the Internet. But nowadays you will only be able to purchase a 4 or 8MB video card second-hand, because they are no longer being manufactured. 32MB cards are easily available, but you would probably struggle to buy a new 16MB card. Therefore any video card you purchase new will be able to handle office and Internet tasks with ease.

Note that to avoid eyestrain, the refresh rate of the monitor should never be set below 72Hz.

The refresh rate is the rate at which the screen redraws itself. The higher the redraw rate the more solid the image appears, and hence the less the eyestrain.

Therefore, you should make sure that the monitor supports 72Hz as a minimum refresh rate for every screen resolution that you set it at. Any refresh rate below this is considered to cause eyestrain.

For instance, a cheap 17" monitor might support a maximum resolution of 1600x1200, but only at a refresh rate of, say, 60Hz. If this is the case, use a lower resolution setting that has a refresh rate of at least 72Hz.

The most comfortable refresh rate at any resolution is 85Hz. When you buy a new monitor you should check to see that it supports an 85Hz refresh rate for the resolution you intend to use.

14" monitors should have a maximum resolution of 800x600.

15" monitors should have a maximum resolution of 1280x1074.

17" monitors operate optimally when displaying a resolution of 1152x864, but will have to use a lower refresh rate to display the higher 1280x1024 resolution. A refresh rate of less than 75Hz should be avoided because of the flickering that takes place, and which can be damaging to eyesight.

19" monitors operate optimally at a resolution of 1280x1024, but can usually operate at a resolution of 1600x1200, which is only acceptable if the refresh rate is 75Hz.

Remember that most new monitors will operate optimally at 85Hz, so check what resolutions a monitor supports at that (vertical) refresh rate.

The larger the screen size, the higher the resolution needs to be in order to obtain a solid image.

The higher the resolution, the more information the screen can contain. If you have a 15" monitor set at a resolution of 1024x768, try using a resolution of 800x600, and you will see that it appears as if you have zoomed in on the screen's contents, because there are fewer pixels used on the screen - they are more widely spaced - and the image is therefore bloated.

You should also note that if you cannot find a competitively-priced monitor that comes with a three-year warranty, you are not looking hard enough, because most monitors come with that kind of warranty - even the monitor that comes as part of a PC package.

How to avoid monitor image persistence (screen burn, burn-in)

Note that a laptop computer's warranty does not allow its owner to claim for screen burn, because it is a natural property of the monitor.

Computer users who use programs that don't have set and fixed text menus and that use a white screen to display constantly changing text most of the time, probably won't have any problem with screen burn (burn-in) in a flat-panel LCD or an old-style CRT monitor.

However, both LCD and CRT monitors can suffer from burn-in (screen burn) when the computer to which they are attached run the same application that displays the same screen most of the time.

It is possible with an old-style CRT monitor to be able to see a text menu remaining on the screen even when the monitor itself is switched off. That can't happen with an LCD screen, but a previous image can become stuck and be viewed when the monitor is switched on.

With CRT monitors, if an image or menu is displayed in the same place on the screen for a long time, the same kind of bombardment by the cathode rays in that area can burn the screen phosphor so that it remains showing that display forever.

With LCD flat-panel screens , the same problem can be as bad or worse. This is because, with a liquid-crystal display, the crystals change their state when a voltage is applied to them, and, if left in the same state for too long, they can become stuck in that state. LCD-monitor manufacturers call that property "image persistence". Fortunately, unlike screen burn in CRT monitors, image persistence in LCD screens can almost always be reversed by displaying a white screen or by reversing the colours in the image that caused the problem (by displaying a colour negative of the image, etc.).

The following article on the subject suggests preventative methods, such as using a screensaver or using appropriate power-saving settings under the Windows Power Options in the Control Panel (in Windows XP and Windows Vista using its Classic View option).

L CD Image Persistence -

http://compreviews.about.com/od/monitors/a/LCDBurnIn.htm

In Both Windows Vista and Windows XP, you set a screensaver to work by right-clicking and empty space on the Windows Desktop. Next, click on Properties on the menu that comes up, and then open the Screen Saver tab in the Display Properties window.

If you have set a logon password in Windows XP Home Edition, you can use a key combination to bring up the logon screen so that it works in the same way as a screensaver. No one can use the computer until the password is entered, and when it is entered, you resume immediately from where you left off. To bring up the logon screen, just press one of the two Windows keys (they have a Windows flag on them) and the L key. This also works in Windows XP Professional Edition, but there is no need to set a password, because it requires the user to set a password during its installation.

You can almost certainly also do that in all of the different versions of Windows Vista.

Setting CRT screen resolutions and refresh rates, etc.

For Windows Vista, read Getting the best display on your monitor. The article covers CRT and LCD flat-panel monitors.

For Windows XP, read Display Properties overview. It covers both the Home and Professional versions of Windows XP.

In Windows 9x systems (Windows 95/98/Me), the screen resolutions and the refresh rates are set by using the options given in the Display Properties window, which has several tabs. You want to use the Settings tab.

In Windows 9x systems, you can access the Display Properties window from Start => Settings => Control Panel => Display icon. Or you can use the right mouse button to click an empty space on the Windows Desktop, and click Properties. The Display Properties window comes up.

You set the colour depth (Colors), and screen resolution (Screen area) on the Settings tab.

If you want to set the screen refresh rate, click the Advanced button of the Settings tab, and click the Adapter tab. If the correct monitor is shown under the Monitor heading in the Device Manager (click the System icon in the Control Panel, or use the right mouse button to click on the My Computer icon, and click Properties), then the refresh rates shown can all be safely set.

But note well that if the wrong monitor is shown in Device Manager, the refresh rates might not be supported. If you use a refresh rate not supported by a CRT monitor you can damage it permanently, so make sure that the correct monitor is shown in the Device Manager. The Windows standard plug and play monitor is not dangerous because any new monitor will support the refresh rates and screen resolutions that it provides in the Display Properties window.

You can change the monitor by highlighting the monitor in Device Manager, and clicking the Remove Button. You then open The Add New Hardware utility in the Control Panel. You can allow Windows to detect the monitor as new hardware, or you can pick the make and model from a list. If Windows cannot detect your monitor, rerun the Add New Hardware utility and pick the option that allows you to select it from a list. You come to a screen that has the names of all of the kinds of hardware that can be installed. Look for your make and model of monitor under the Monitors heading.

If you cannot make Device Manager show your make and model of monitor, install a standard monitor. You can then try visiting the manufacturer's website to download an ID file that you can install manually.

A service tip from computer forums: Remove dust from the inside of a CRT monitor to extend its life or make it work properly

1

"I had a [CRT] monitor doing that same thing [making popping noises when switching it on] and had it repaired. They replaced the high voltage flyback transformer. Anyway, now it works great and has been for the last 2 years. I watched the tech doing the job and when he opened the monitor case, about a pound of dust fell out. He asked me if I ever cleaned out my monitor. I didn't know what he was talking about. He told me that the monitor needs to cool and has vents on the bottom and top. Cool air comes in from the bottom and hot air exits out the top. It if gets clogged with dust, then it overheats components. He suggested that every week take the vacuum cleaner with brush attachment and hold the vacuum on all the openings of the monitor for 4 or 5 seconds to suck out all the dust. It will double or triple the life of your monitor. I've been doing this and it works great. Make sure to get the intake and other ducts on your computer at the same time."

2

"When I booted up this morning, my monitor, a Sony Triniton Multiscan 300sf 21" CRT, (which I've been very happy with) was not good, everything from print to icons had this wide streaking about a half an inch coming from left to right, and getting worse as each minute passed. Unfortunately there is no degauss, so I tried resetting with no luck, then updating the video driver, still no luck. Not wanting or ready to buy another monitor, I decided to turn off, unplug everything and open up the [monitor's] case. It was a bit dusty, so armed with canned air, no-lint swabs and a small soft brush I went to work. After plugging everything back in and booting up, voila! monitor is great once again!"

Note well you should not open a CRT monitor unless you know what you're doing, because some of the circuits act as a large capacitor, and can store a large charge for a long time, even when they're turned off. The electronics at the narrow end of the cathode ray tube that is closest to the back of the case needs the most caution. You can blow or suck dust from it, but you shouldn't hold the tube with one hand and brush it with the other hand.

Moreover, note well that you shouldn't use a vacuum cleaner to clean the internal components of a PC, such as the motherboard and adapter cards because a static discharge would destroy them. That is why spray cans of compressed air are use instead. However, you can use a vacuum cleaner to clean the outside of the case.

Sundry monitor information

Monitors are made with interlaced or non-interlaced refresh rates.

However, it would be difficult to find a new monitor that has interlaced refresh rates, because this is the inferior option and as such has largely disappeared.

Interlaced means that the screen is not redrawn for every refresh cycle, some are missed. The more refresh cycles that are missed, the more the screen flickers, and the more your eyes are strained. For instance, on an interlaced monitor, the screen might be redrawn every third refresh cycle instead of being redrawn every cycle, as is the case with a non-interlaced monitor. I dare say that it is still possible to be lumbered with an interlaced monitor made in the Far East, so this is something worth checking before you buy.

It would be just as difficult to find an entry-level video card that could not handle Internet access or run office applications with ease.

However, if high performance is wanted for gaming, CAD, or intricate desktop publishing, you will need a 64- or 128-bit video card with 16, 32, or 64MB of RAM.

Most PCI video cards are 32-bit, and AGP video cards are either 64- or 128-bit cards.

Of course, the higher the number of bits that a piece of hardware can process at once, the better its performance will be.

If you have a DVD-ROM drive or plan to install one, you should check that your video card supports the DVD format.

You can use a DVD decoder card that connects to the video card, or use DVD software drivers to play DVD movies, etc. It is not a standard that every card supports DVD yet, but it is possible for the video card manufacturers that have not provided DVD software support for their cards to do so via driver updates.

Games' players require the best 3D performance they can afford. As mentioned under Gaming of this section, there are currently two main standard 3D programming interfaces - Microsoft's DirectX and OpenGL.

DirectX is the most prominent of them, and is currently at version 10.

Therefore, for the greatest versatility, a video/graphics card that supports both DirectX and OpenGL would be the most desirable, since not all cards do support both of them.

If you want to know more about the technical details to do with computer monitors, visit this article - How Computer Monitors Work.

You can also use the Google search box at the top of this page (with its Web radio button enabled) to research any make and model of monitor. Just enter the relavant word(s). Use double quotation marks if the search contains more than a single word or use + between the words. For example, enter a phrase such as lcd + monitors to locate other articles and vendors.

PowerStrip - Shareware - $29.95

"PowerStrip [at version 3.6 in May 2006] provides advanced, multi-monitor, programmable hardware support to a wide range of graphics cards - from the venerable Matrox Millennium I to the latest ATI X1900 Crossfire and NVidia Qual-SLI 7900. It is in fact the only program of its type to support multiple graphics cards from multiple chipset vendors, simultaneously, under every Windows operating system from Windows 95 to the x64-bit edition of XP. A simple menu that pops up from the system tray provides access to some 500 controls over your display hardware, including sophisticated color correction tools, period level adjustments over screen geometry, and driver independent clock controls. A powerful application profiler can detect when programs are launched and respond by activating specific display settings, gamma adjustments, performance switches and even clock speeds - returning everything to normal when the program closes. In-game gamma hotkeys let you light up the darkest hallways during game play, and hardware control over refresh rates - with floating point precision - ensure you're never stuck at just 60Hz no matter what OS you're using. A quick setup wizard gets you up and running with minimal fuss, extensive context-sensitive help is available for all controls, and live updates are supported to ensure you're always running the latest release. Finally, an assortment of system and productivity tools - among them, extensive diagnostics, PCIe and AGP device configuration, EDID decoding and jig-free updating, desktop icon management, a system idle thread, Windows resource monitoring, an anti-burn-in orbiting option, physical memory optimization, an on-screen display, and the most advanced monitor support in the industry - round out the compact 800kb package." - http://www.entechtaiwan.com/util/ps.shtm

A common display problem

Problem

All of a sudden there is no blue showing on your monitor.

Solution

The most common cause of a missing colour occurs when the monitor plug is not properly inserted in its socket.

Colour pictures are made up of red, green, and blue, shades of which are combined to form all of the other colours. Each of these primary colours has a separate pair of pins in the VGA connector. If the plug is half way out of the socket, one or more of the pins will not be able to make proper contact, and a colour will go missing. It is usually red, because its pins are nearest to the edge of the plug.

If the condition above is not the cause, a broken pin, or a severed wire in the cable is the most likely cause.

You can easily check the pins on a standard monitor cable.

On the male VGA connector on the end of the cable (the female connector is the VGA port on the video card), the pins are numbered from left to right starting at the top - pins 1 to 5 in the top row, 6 to 10 in the middle row, and 11 to 15 in the bottom row. There are only meant to be four pins in the middle row, because Pin 9 is deliberately missing. On some older monitors, other pins (4, 12, and 15) might also be missing, because the use of missing pins was an early method of signalling the monitor's capabilities to the computer.

If the cable and the pins are in good order, the colour problem will probably have been caused by a fault in the video card. It is not economical to repair adapter cards, so, if you don't have a spare video card to test the system, or you can't obtain one from a friend or other source for testing purposes, you will have to purchase a new video card in order to remedy the problem.

It is extremely unlikely that the missing colour is caused by a fault in the monitor, because of the way in which a colour monitor displays colour cannot normally be made to produce such an error.

Note that if a monitor has outlived its three-year warranty, unless it is a particularly expensive model, it would be cheaper in the long run to replace it than it would be to have it repaired.

PC Monitors: Reviews

Computer Shopper (UK)

Computer Shopper - CRT monitors:

http://www.pcpro.co.uk/shopper/archiveproductsearch/11/CRT-monitors

Computer Shopper - LCD/TFT monitors:

http://www.pcpro.co.uk/shopper/archiveproductsearch/40/TFT-monitors

Computer Shopper - Latest Reviews - the latest computer hardware and peripherals, including printers:

http://www.pcpro.co.uk/shopper/reviews/latest/

Over 3,000 reviews are browsable by category or company name.

Computer Shopper Laboratory (tests):

http://www.pcpro.co.uk/shopper/labs/

Computer Shopper Hotlist - hot computer products, including printers:

http://www.pcpro.co.uk/shopper/reviews/hotlist/

Anandtech.com

Display reviews - http://www.anandtech.com/displays/

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PC Buyer Beware! Copyright © Eric Legge 2004-2008. All rights reserved.