Selasa, 07 Juni 2011

Laptop has bad video on the LCD screen. What is wrong?

Here I’m going to post some laptop screen photos showing bad video output. I’ll explain what was wrong with the screen and how I fixed it. I plan to ad more examples as soon as I get new pictures. If you have your own example (and know how to fix it) please let me know and I’ll post it too.
Here’s some help for finding a correct part for your laptop.
Other post related to troubleshooting laptop video problems:
How to troubleshoot and fix laptop video problems
Taking apart notebook LCD screen
Replacing LCD screen inverter
The newly installed screen is not working
Example 1.
Here’s a picture of Satellite M55 LCD screen I made this morning. I got this video output as soon as I started the laptop. There were a lot of vertical lines, and they were changing color without any pattern. To me it looked like Northern Lights (never seen in real life) :) . The external monitor worked fine.
LCD screen no image
As soon as I applied some tension to the screen it changed the pattern. Some horizontal lines appeared in the middle of the LCD.
LCD screen horizontal lines
Here’s the difference. When I torque the screen, the image appears but it’s distorted with some horizontal lines running across the screen.
Reseating the video cable didn’t make any change and the problem was fixed after I replaced the LCD screen.
Example 2.
I took this picture from Toshiba Satellite M65. I think that this example is very typical. One day you wake up, turn on the laptop and see one or a few hair-like vertical lines in different colors.
Laptop LCD vertical lines
When you move the LCD screen some lines might disappear or more lines appear on the screen. A video output on an external screen would be perfect, without any lines. Unfortunately, these lines indicate a screen problem. I’ve never seen this kind of video output caused by a bad video cable or bad FL inverter board. My laptop was fixed after I replaced the LCD screen.
Example 3.
The photo below comes from Toshiba Satellite 5205. The laptop displays identical vertical lines all over the LCD screen as soon as I turn it on. Sometimes these lines are red, sometimes they are blue, sometimes they become wider and change color to white.
Laptop screen vertical lines
The same pattern appears on the external monitor. It displays same vertical lines. When the same video defect appears on both monitors – internal LCD screen and external screen, then most likely it happens because of a bad video card. On some laptops the video card is integrated into the system board, on other models it’s a separate module.
External screen vertical lines
In this example, the vertical lines were caused by a failed video memory on the system board. I’ve tested the video memory with Microscope utility and it failed the test. In Toshiba Satellite 5205 the video memory is integrated into the system board. To fix the problem, I’ll have to replace the board. (We do not have equipment to replace the memory module itself).
Example 4.
Here’s another example of a bad LCD screen. My bad! It wasn’t the LCD screen problem.
Bad reddish laptop screen
As soon as I turned on the laptop, I was getting these reddish marks on the LCD screen but not on the external monitor. Reseating and replacing the video cable didn’t help. The problem disappeared when I installed my test LCD screen. Yes, for some reason I wasn’t able to reproduce the problem on my test LCD screen. But the reddish video appeared again as soon as I replaced the screen. I guess it happened because the system board had some kind of intermittent problem with onboard video or video connector. Long story short, I had to replace the system board and it fixed the problem. Yep, I misdiagnosed this laptop.
Example 5.
Here’s one more example of a faulty LCD screen. The left half of the screen works just fine but the right side is completely white.
Half LCD screen not working
Example 6.
Here’s another laptop with a bad LCD screen. This time it’s a tablet PC.
Vertical stripe on LCD
Example 7.
This screen looks like the screen on the example 1. I hooked up an external monitor and the external video works perfectly fine.
vertical lines
Here’s the difference. When I torque the screen, the image appears but it’s distorted with some horizontal lines running across the screen.
distorted image
After a few seconds the image washes away.
Image washes away
I had to replace the LCD screen.
Example 8.
This laptop displays inverted colors right from the startup. As you see, the Toshiba logo is light green instead of red. The background is light gray instead of black. The Intel logo should be blue on a white background but it is red on a black background.
Inverted colors
When your laptop displays inverted colors as on the picture above, this is an indication of a bad screen. You’ll have to replace the screen.
Example 9.
Here are two more screens. In both cases this problem is related to the LCD screen, witch means the screen has to be replaced.
On the image below you see a white band running from the top of the screen to the bottom. This band appears right from the laptop startup and runs through the logo too.
White band running from top to bottom
On the following image only the left side of the screen is working properly. This problem is caused by faulty LCD screen.
Only left side of the screen works
Are you looking for a new LCD screen for your laptop?

Screen inverter replacement. Fixing laptop backlight problem.

Here’s an example of replacing the FL inverter board on an IBM ThinkPad T41 notebook. This guide will work fine for any other IBM notebook. Replacing screen inverter on other notebooks like Dell, HP, Toshiba, etc… will not be much different.
Replacing inverter board on IBM ThinkPad T41

First of all, unplug the AC adapter and remove the battery.
In order to access the inverter board you’ll have to remove the LCD screen bezel. On most laptops screws are hidden behind screw seals. In this case we have 5 screw seals on the front. Carefully remove the seals with a sharp object and glue them on the LCD bezel, in this case you will not lose them. Remove all screws and mark them somehow so you are not confused when you assemble the notebook back.
Remove screw seals and screws
Some laptops also have screws on the side of the display. This notebook has 3 screws on each side. Remove screws seals and then remove screws.
Remove screw seals on both sides
Start removing the LCD bezel with all fingers. Carefully wiggle the bezel to release plastic latches. Never use any sharp object during disassemble because you can accidentally damage the screen.
Lift up LCD bezel
If latches are very tight you can use a guitar pick to unlock them. Insert the guitar pick between the LCD bezel and cover and carefully move it alone the side.
Removing LCD bezel
This notebook allows you to replace the inverter board without removing the LCD bezel completely. Lift up the bottom part of the bezel and remove one screw securing the inverter board to the LCD cover. This location is very common for the screen inverter. On most laptops you’ll find it under the display bezel below the screen.
Remove screw from the inverter
Carefully lift up the FL inverter and rotate it a little bit. Unplug cables on both sides. The left side of the inverter board connects to the video cable, the right side to the backlight bulb (CCFL tube) inside the LCD screen. Remove the inverter and replace it with a new one.
Disconnect inverter cables
To find a new inverter board (and any other spare part too) for any IBM notebook you should use the FRU number from the part.

Inverter FRU part number

the LCD screen can be easily damaged if you open it up. If you do something wrong the screen might become completely unusable and you’ll have to buy a new screen. It’s very expensive. Think twice before you decide opening the screen. Continue at your own risk. Here’s my Dell Latitude D610 notebook with water damaged screen I’m going to take apart.
First of all remove the battery from the notebook.
Laptop screen repair

Lift up rubber screw seals and remove all screws.
Remove LCD bezel
Carefully separate the screen bezel from the LCD cover and remove the bezel.
Open notebook display
Remove two screws from the front and two screws from both sides.
Remove LCD screen
Carefully remove the LCD screen from the cover and place it on the notebook base. Disconnect the video cable and the inverter board cable.
Disconnect LCD cables
On this model the inverter board is attached to the screen with two screws. Remove both screws, disconnect the screen cable and remove the inverter board.
Remove screen inverter
Carefully peel off sticky tape and foil and put it aside. You’ll have to put it back in place during the screen reassembly.
Remove securing tape
Remove two screws from both sides of the screen.
Remove screws from bouth sides
Carefully place the screen upside down on a flat surface. Carefully unglue the film that covers the circuit board and remove two screws from the board (top circles). I wasn’t really sure if I have to remove screws on the bottom, so I removed them just in case. Do not touch the circuit board with fingers.
Open LCD screen
After both screws are removed you should be able to lift up the circuit board. Be careful, it’s still attached to the LCD.
Lift up circuit board
Start unsnapping the metal frame from the screen. There are a lot of latches on all sides of the screen. You can unlock them with nails or a small flathead screwdriver.
Unsnap LCD screen frame
After all latches are opened you should be able to separate the screen into three pieces: metal frame, LCD and background (not sure about correct technical name).
If you have lint or dust inside the screen, probably you’ll find it between the LCD and the background. Do not touch LCD or background with your fingers. I was able to remove dust and lint up with a very soft cloth, barely touching the LCD and background surfaces.
After I split the screen I found that the background has a few some kind of optical layers (three transparent sheets) and in my case they were damaged by water. The water dried out and left stains between these optical layers.
In my case removing dust and lint wasn’t enough and I had to go further.
Split notebook screen
Very carefully separate the LCD with attached circuit board from the background.
Separate LCD
To remove damaged optical layers it’s necessary to remove metal locks on both sides of the screen. It’s like a small clip that keeps layers in place.
Remove screen locks
After I removed both clips, I was able to look between the layers. At first I tried to clean up the dried water marks with a soft cloth but it didn’t help. The stains were still visible and didn’t want to go away.
Fortunately I had another similar screen laying around, it had a cracked LCD. I decided to borrow the optical layers from the cracked screen and transfer them to my screen. I wasn’t sure if it’s going to work, but as I mentioned before I didn’t really care if I break the screen. It was just an experiment.
So I disassembled the cracked screen and carefully transfered the white background and all transparent layers to my screen.
transfer damaged screen layers
After that I assembled my screen back removing dust and lint with a very soft cloth. Breathlessly connected my new screen to the notebook. Turned it on and…
That’s a miracle, it works!
No dust, no lint, no water mars inside the screen! It’s clear and the background is absolutely clean!
LCD screen works again
My donor screen had a cracked LCD but it had a good working backlight tube. The backlght tube is very fragile and it’s located inside a metal casing. I didn’t remove the backlight tube, I just broke off the entire metal casing from the plastic frame. I’m going to use this backlight tube for testing purposes.
Test backlight bulb
Here are some tips and tricks for troubleshooting and fixing laptop video problems. Video issues are very common within portable computers and with the following tips you should be able to detect and eliminate basic laptop video problems.
Laptop LCD screen has a faint image.
Faint image on laptop screen
Look at the LCD screen very closely and check if you can see a faint image on the screen. It’s possible that the LCD lid close switch stuck in the “closed” position and the backlight stays off even when you open the LCD screen or turn on the laptop. The switch turns off the backlight when you close the LCD display to save the laptop battery power. Check the LCD lid close switch. Usually it is a small plastic pin located close to the LCD hinges. Try to tap on the switch a few times to turn on the backlight. If after tapping on the LCD lid close switch the backlight stays on, you fixed the problem.
It is also possible that after tapping on the LCD lid close switch the backlight works fine, you see a normal video on the screen for some time and then the backlight turns itself off again. In this case I would blame the FL inverter board. Try to reseat cables on both end of the FL inverter to make a better contact between the cables and the FL inverter board. If it doesn’t help I would try to replace the FL inverter board.

Laptop LCD screen is solid white color.
Screen is white
Most likely it is just a bad connection between the LCD display and the system board. I would try reseating the video cable connector on the back of the LCD screen first and check if it fixes the problem. After that I would try reseating the video cable connector on the system board. I would also try reseating cables if there is no video on the LCD screen at all.
The video on the LCD screen is garbled.
Bad image on laptop LCD screen
Try to connect the LCD screen to an external monitor. If the external video is fine, you have a problem with the LCD screen or the LCD video cable. You can try to fix the problem by reseating the video cable on the back of the LCD and on the system board.
If you see the same garbled video output on the external monitor most likely it is not the LCD screen problem. In this case the system board (with onboard video) is bad or the video card is bad.
I understand that these tips will not cover all video problems with portable computers. If you have a different problem, you are welcome to leave a comment and I will try to help you if I can. :)
Special to thanks laptoprepair101
ucokmonalisa com
Here is a simple diagram that will help you to understand how a notebook display assembly works and how an image appears on the screen. I’m not an artist and I tried my best drawing this diagram, so if you cannot see a laptop in this picture, don’t be mad. :P
Notebook Display Assembly Diagram
A generic display assembly includes a very few parts and knowing them will help you to understand witch part can cause a problem if you laptop video not working properly.

Video cable. A video signal from the motherboard goes to the LCD screen through the video cable. The video cable connects to the motherboard (or video card) through the connector 1. The video cable connects to the LCD screen through the connector 2. The video cable (in most cases) is also responsible for supplying a necessary voltage for the FL inverter board. The video cable connects to the FL inverter board at the point 3.

FL inverter board. This board is responsible for converting low voltage DC power (point 3) to high voltage AC (point 4), necessary to light up the backlight bulb. If the FL inverter board is bad, the LCD screen (backlight bulb) will not light up when you turn on the laptop, but you still should be able to see a very dim image on the screen.
Looking for a new screen, video cable or inverter board? Find it here.

CCFL (backlight bulb). When the backlight bulb lights up, you can see an images on the LCD screen. In most cases the backlight bulb is a part of the LCD screen and if it’s bad, the entire screen has to be replaced. By the way, some specialized repair shops can replace the backlight bulb itself.

Lid close switch. The lid close switch is a small button that locates close to the display hinges. On some newer models there is no button, because the switch is magnetic. You can set up your laptop to go to a hibernation mode or to a standby mode when the LCD is closed. It’s done through power management software. These modes are triggered when the display is closed and the lid close switch is pressed down. If the LCD screen on your laptop will not light up when you open the display assembly, check the lid close switch is stuck inside (it might happen because the switch is dirty).

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