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LCD Diagnostics

My LCD Screen has a faint Image.
You will have to look very closely at the LCD as it can be difficult to see. But if you do see a very faint image then it is likely to be the backlight that for some reason is not working. Sometimes it can also be the Inverter or both. The backlight is a long thin phosphorous light tube that projects light through the LCD panel. I bit like the kind of Light tube you may have in a office but a lot smaller.

Pink or discolored screen or flickering on and off.
This is a straight forward Backlight problem. The solution is to change the backlight.

Checking Lid Switch.
One other reasons could be the lid switch. This could be stuck in the closed position or faulty. The switch works in the way to save the battery power when you close the lid. It could also off course still be a faulty backlight witch would need replacing. But check the switch first by disabling it. Some have connectors that you can simply disconnect. Others you will have to use a multimeter to test if the circuit is shorted. To get to the switch you will have to disassemble the laptop. Check our shop for the DVD Tutorial Video as this will be of great help in the disassembly. I don’t recommend that you disassemble your LCD Screen as some can be very tricky and need an opening slider tool, Others may be glued.

Quick test of Lid Switch.
Tap on the switch and around the switch area incase the switch is stuck, should the screen light up and stay lit then you can blame the switch, then the backlight is fine in that case. Leave the lid open and laptop on for some time should you find the backlight all of a sudden switch back off then it suggests a problem with the Inverter Board. It is worth checking the cables to and from this board. This would mean some disassembly on the screen. The inverter board is located in the lower center of the LCD Screen and connects to the Backlight.

DANGER BEWARE
The Inverter can be very dangerous and can kill you. !!
(Disconnect the power and remove battery)

Inverter
Sometimes the Inverter will make buzzing noise this is a good indicator that it is going or gone. Check the Connections on both ends of the board. Do not touch anything on the inverter board If you still have the problem then the Inverter Board will need replacing.

My Image on my screen is Garbled.
Use an external monitor to diagnose this problem. If the screen image is good on your external monitor then you probably have problems with the LCD Screen, It is worth checking the LCD cable on the motherboard, below the top control panel. And on the back of the LCD. If you still get garbled image on the external monitor then it will be the Graphics or a System Board failure (Motherboard). This would likely need to be replaced.

Horizontal or Vertical Lines running through your Screen.
With Vertical Lines this usually happens due to fatigue of the screen flat cable connectors on the top back of the LCD Screen. As you may notice that your screen will twist slightly.
Carrying your laptop by the LCD Lid is also a common cause. Basically what happens is the ribbon cables that feed the LCD are sandwiched inside of the LCD Panel at the top of the screen and the twisting constantly wil break some connections resulting in red, green, blue and white lines. Once this happens you cant really repair it. Screen replacement would be needed at some point. You should still be able to connect and use an external monitor.

With Horizontal Lines
or Very Large Vertical Blocks then it usually is the graphics that is the problem.

LCD Screen is all White or Black Again
Check LCD Cables, most likely it could be the Cables inside the LCD Screen that needs to be checked. Failing that, it could be your Graphics or System Board.

Pixilated blocks, corrupt characters or letters, artifacts etc.
Everything is fine then after a while you get this problem and the computer switches off. This will be an overheating problem of Graphics chip or more usual CPU Overheating. Check Fans and heat sinks, Recommend re pasting with Heat Sink Compound.

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Common Layout of an LCD Screen
 
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LCD Layers
 
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In color LCDs each individual pixel is divided into three cells, or subpixels, which are colored red, green, and blue, respectively, by additional filters (pigment filters, dye filters and metal oxide filters). Each subpixel can be controlled independently to yield thousands or millions of possible colors for each pixel. CRT monitors employ a similar 'subpixel' structures via phosphors, although the electron beam employed in CRTs do not hit exact 'subpixels'. Because they utilize red, green and blue elements, both LCD and CRT monitors are direct applications of the RGB color model and give the illusion of representing a continuous spectrum of hues as a result of the trichromatic nature of human vision.

Color components may be arrayed in various pixel geometries, depending on the monitor's usage. If the software knows which type of geometry is being used in a given LCD, this can be used to increase the apparent resolution of the monitor through subpixel rendering. This technique is especially useful for text anti-aliasing. To reduce smudging in a moving picture when pixels do not respond quickly enough to color changes, so-called pixel overdrive may be used. 
 
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Common CCFL Converter
 
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Cold Cathode Florescent Lamp (CCFL Backlight)
 
 

 

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Muswell Hill
London N10
UK

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