LCD Monitor Problems

LCD Monitor Problems – Introduction

This article aims to help identify some common LCD monitor problems and details the techniques you may use to help you to resolve them.

LCD monitors, due to the fall in prices in recent years coupled with their many benefits such as size, weight, clarity and aesthetics to name but a few has led to their adoption by the masses – hey, how often do you see any old CRT type monitors these days!

With the advent of LCD displays comes their own, very different to the CRT type monitor, set of potential problems.Before we get into discussing LCD monitor troubleshooting in detail we should perhaps spend a little time understanding the basics of the workings of an LCD monitor which will help us in our understanding of any LCD monitor repairs we may undertake.

LCD Problem

LCD Monitor Problems – How LCD Monitors Work

Today’s LCD monitor has evolved from the use of liquid crystal display panels which first appeared in laptop PCs.

These LCD panels contain liquid crystal cells which are actively polarized and act as a polarizing filter controlling the angle of polarization and thereby the amount of light that is allowed to pass through the liquid crystal cell. The liquid crystals are actually minute rod shaped crystals that flow like a liquid.Light, provided by the LCD monitors CCFL or LED backlight, passes through the cell when it is in one orientation but when an electrical potential is applied to the cell it alters the orientation and hence the polarization of the cell which blocks the light from passing through it.

Simply put, a polarized filter allows light waves which are aligned with the filter to pass through. These co-aligned light waves can be blocked by adding a polarized filter at right angles to the alignment of the light wave.

A color LCD display comprises three of these cells for each pixel. Each of these cell triads will be used to display a different color – red, green and blue.

In an active TFT (thin film transistor) matrix LCD display each of these cells are driven by a separate transistor.By activating each of these transistors independently and / or together the amount of light and the color of each cell can be altered allowing the required pixel brightness and color to be displayed.

The light to be passed, blocked or filtered by the active TFT LCD display is provided by a CCFL (Cold Cathode Fluorescent Lamp) or LED (Light Emitting Diode) backlight mounted behind the LCD panel at the back of the monitor.

Incidentally, the first LCD monitors to come onto the scene had very poor refresh rates and they suffered terribly with ‘ghosting and blurring of fast moving images as the crystals refresh rate was so slow.

Now, this was fine for word processing, email and the like but hopeless for watching videos and gaming.

Just think about the sheer volume of pixels that make up a LCD panel with say a 1680 x 1050 native resolution – that’s 1,764,000 pixels! Then factor in the fact that each pixel in a color LCD panel is made up from 3 cells (red, green and blue), and that’s one hell of a lot of separate liquid crystals to toggle on and off!

Then along came the TFT (Thin Film Transistor) LCD panel which used an ‘active matrix’ LCD array packaging three transistors (one for green, one for red and another for blue) per pixel integrated within the display directly behind their liquid crystal display cells.

This active matrix LCD display enabled LCD panels with extremely fast refresh rates to be produced.

Ok, now we have a basic understanding of how an LCD monitor works we can look at and understand some of the common LCD monitor problems that can occur.

LCD Monitor Problems – Bad, Dead or Stuck Pixels

Now, one problem that is specific to LCD type displays is that of the ‘stuck’ or ‘dead’ pixel.

A ‘stuck’ pixel refers to the condition where one of the pixel cells, red, green or blue remains ‘stuck’ on.Similarly a ‘dead’ pixel refers to one where one of the pixel cells remains off.

‘On’ type failures are more common and can be quite noticeable, especially against a dark background where you may notice a tiny red, green or blue dot corresponding to the failed pixel cell.Manufacturers vary in the way they treat such pixel defects dependant upon positioning within the screen and quantity of bad pixels etc.

As the LCD display manufacturing process has evolved the occurrence of bad pixels has reduced to the point where it is very unlikely that you will suffer from this type of fault with a brand new LCD monitor screen.

You may though suffer from bad pixels at any time and generally there is not a lot that you can do once you have them although the following tips may be worth trying before you go out and buy a new monitor.

Before you go any further ask yourself if you are happy with the fact that you may make matters worse?!Ok, for stuck pixels first off you can try tapping on the LCD monitor screen over the area of the stuck pixel with your finger or a rounded off / blunt object.

Try this with the screen powered up and make sure you don’t scratch or damage the surface of the screen. Rubbing the screen in the area of the stuck or dead pixel may also affect a fix.If this fails you can also try using specialist software which will try to cycle the stuck pixel on and off.

Visit UDPixel or JScreenFix and download their software and see if this cures your bad pixel problem.

LCD Monitor Problems – Poor Image Quality

Although LCD TFT displays do not suffer from geometry problems like the old CRT displays they can suffer from other problems which cause poor image quality, especially exacerbated by the use of the old analog VGA interface.

Always make use of the digital DVI interface to drive your LCD TFT monitor wherever possible.

Check out your PCs graphics card and if it has a DVI interface and so does your LCD display then use it!

LCD displays have digital control panel settings to allow the user to adjust brightness, contrast, vertical and horizontal shift etc.

These settings are stored in the LCD monitors NVRAM (non volatile RAM) as permanent storage of the user settings.LCD displays do suffer from ‘pixel jitter’ or ‘pixel swim’ whereby adjacent pixels turn on and off due to the digital resolving of an analog signal when the monitor is supplied via a VGA analog interface.

The best way to overcome or reduce this problem if you have to use a VGA type interface is to use the LCD monitors auto-tune or auto adjust option within the OSD (On-screen Display).

The OSD allows you to adjust various aspects of your LCD displays image such as the color, brightness, picture offset (vertical and horizontal), contrast etc.

There is usually an auto image adjustment feature and a restore default settings option that should allow you to reset your LCD monitor image settings.

The OSD also allows you to adjust the color temperature of your display if your image should appear too blue or red for example.

Windows 7 provides a ‘Display Color Calibration’ wizard that allows you to set up your displays gamma, brightness, color and contrast together with a ‘ClearType’ adjustment so that you can achieve a really sharp, crisp and clear image.

To access the wizard go to ‘Start’ and type ‘DCCW’ in the ‘Search programs and files’ box and then hit ‘Enter’. This will bring up the ‘Display Color Calibration’ wizard’ and will guide you through the steps required.

LCD Monitor Problems – Native Resolution and Pixel Mapping

Another cause of poor image quality or a ‘fuzzy’ looking or blurred display is due to using an LCD TFT monitor at a resolution other than the screens native resolution.

All LCD panels have a native resolution which is set by the amount of pixels incorporated into the active matrix TFT panel, e.g. 1680 x 1050.

To view text and images as crisply and clearly as possible without stretching or compressing the image to be displayed avoid setting the resolution to any other resolution setting options via the Windows Display Properties setup in control panel – where possible ensure that you stick to using your displays ‘native resolution’ setting.

Because an LCD panel has a fixed number of pixels in the horizontal and vertical directions, setting the display to any other setting other than its native resolution or an exact division of it will result in the image being stretched or compressed to fill the display with an uneven number of pixels being used per image pixel.

As an example, an LCD display with a native resolution of 1600 x 1200 would give a perfectly acceptable image when set to 800 x 600 as this is an exact division of its native resolution and can simply double up on the amount of pixels used but setting it to say 1280 x 1024 it is not an exact division and will result in a poor quality image display due to the LCD monitor trying to resolve between pixels.

Some monitors are available that perform 1:1 pixel mapping which gets around this problem to some extent when reducing the resolution but this will result in bands around the edge of the image due to the blacked out unused pixels.

LCD Monitor Problems – Text to Small!

When using a small screen size at high resolution text and icons can become very difficult to read especially for someone whose eyesight is not so good!

At low resolutions text and icons are large and easy to read but due to the fact that Windows menus and text are set to a fixed pixel width and height, as you increase the screen resolution for the same LCD physical panel size the text becomes progressively smaller and more difficult to read!

Sure, you can get more of your documents etc on the screen but viewing them may become very hard on the eyes.

If you really want a high resolution display but find you are having trouble reading the text and icons etc then you will need to look at changing your LCD monitor to one with a larger size panel – say maybe a 22, 24 or even a 30 inch panel with a similar native resolution to the smaller screen size.

Another option if you are finding it difficult to read text on your LCD monitor screen is to make use of Microsoft’s ‘ClearType’ feature which is available in Windows XP onwards.Activating Windows ‘ClearType’ is simple – just right click on a blank area of your Windows desktop, select ‘Properties’ and then within the ‘Display Properties’ window select the ‘Appearance’ tab and click on the ‘Effects’ button.

You will now be presented with the ‘Effects’ window where you should select ‘Use the Following Method to Smooth Edges of Screen Fonts’ and then select the ‘Clear Text’ option from the drop down menu.

Click ‘Ok’ twice and Windows ‘ClearType’ will be activated providing shading to your text which should make it easier to read.

LCD Monitor Problems – Dim Display

Your LCD monitor screen produces a bright display by the use of a CCFL backlight. Over time these lamps in the back of your monitor may begin to fail and eventually fail completely making your LCD display pretty much unreadable.

Usually the backlight will start to dim or may take a little while longer to reach full brightness – this is a sign that the backlight is on its way out and will eventually fail altogether.

Can you fix it?

Well there are some specialists that offer this service but it really isn’t worth the cost in our opinion.

Accept your loss and go buy a lovely new widescreen LCD TFT display - LCD monitor problem gone :)

LCD Monitor Problems – No Display

A blank screen may not necessarily mean that your LCD monitor has died.

Before you go off looking for a replacement screen try a few of the following basic LCD TFT troubleshooting steps to ensure that it really has in fact died.

  • First off check that your PC monitor is receiving a power supply – is the power on indicator LED on the front of your LCD monitor yellow or flashing green? If it is your LCD monitor is in power saving mode and a quick wiggle of your mouse will take your PC back out of standby mode. If not try replacing the monitors power cord or fuse. A permanently green LED indicator means that your LCD display is receiving power and a signal from your graphics card so you just need to adjust the screen brightness / contrast.
  • If your monitor is receiving power do you see an image on the screen during initial boot up of your PC? If you do and then it disappears when Windows starts to load up then it is probably a problem with your graphics card drivers – try downloading the latest driver for your graphic card and installing it to see if this cures the problem. How do you do this with no display you may ask! Simple, just boot up in ‘Safe Mode’ by pressing the F8 function key during startup. This prevents the graphics card driver being loaded and allows you to see Windows, albeit in a reduced display resolution format. Now you can load up the latest drivers that you downloaded by going to ‘Control Panel’, ‘System Properties’ and selecting the ‘Hardware’ tab. Now click on the ‘Device Manager’ button and go down the list until you see your graphics card which will be located in the ‘Display Adapter’ section. Right click on your graphics card listing and select ‘Update Driver’. You can now install the latest driver for your graphics card by following the on screen prompts. If your LCD monitor also has a driver then you should also update this to the latest using the above outlined procedure.
  • If your LCD monitor is still blank after following the above instructions to update the drivers then try disconnecting all external drives except for your monitor, mouse and keyboard. Re-boot your PC and if it starts up in to Windows then you have a device problem – try connecting them back one at a time until the problem returns and you’ve now identified the culprit.
  • Try connecting your LCD monitor to another PC and if it still doesn’t work try another set of Power and VGA or DVI cables. If you’re monitor works perfectly on another PC then try another monitor on the original PC and if this doesn’t work then it’s likely to be your video / graphics card at fault. Shut down your PC and remove the power cord. Open up your PC chassis and ensuring that you take the necessary static electricity precautions by grounding yourself to your PC chassis or using an anti-static wrist strap, try re-seating your graphics card. Replace your PC covers and try again. If this doesn’t work try swapping out your graphics card.
  • Try removing your LCD displays power cord, waiting for a minute and then reconnecting the power – sometimes this will work as the LCD monitor power supply may have tripped out due to a power surge for instance.
  • LCD monitor input source selector – if your LCD monitor has multiple input source options such as VGA or DVI then you may need to manually activate the other source to the one you are using by pressing the input selector button or try manually switching cables to the other input.

We hope the above tips have helped you with troubleshooting your LCD monitor problems.

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