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. 
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).
Related articles:
Fixing notebook video problems.
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October 18th, 2007 at 11:00 pm
Hi, I have a 5-year-old Dell Inspiron 600m that recently the LCD screen won’t light up. It powers on and powers off fine but the screen stays black right from the beginning. External monitor works OK. I have tried reseating the cable connector but it did not solve the problem. This problem had happened three or four times before and usually after powering it on and off several times, the screen would light up. I noticed that the problem only happened if I turn off the laptop. I used to leave my laptop on my desk all the time and always put it into stand-by mode and I never experienced the problem. Recently, since I travel with my laptop everyday, the problem happened more often and now it’s been almost three weeks the screen did not work. I would like to know if the problem is related to inverter or backlight bulb?
October 13th, 2007 at 9:09 pm
somveer,
This problem is not related to the backlight or inverter. I think this problem is related to the video card.
Make sure to test your laptop with an external monitor. Can you see the same vertical dotted lines on the external screen? If yes, this problem is related to the video card.
If your laptop has shared video (part of the main memory is used for video purposes), run the memory test. If the memory module fails the test, replace it and see if it fixes the problem.
October 13th, 2007 at 9:03 pm
AJAY Jamous,
This disassembly guide has step-by-step instruction for replacing hinges (and hard drive) on a Toshiba Satellite A45 notebook.
October 9th, 2007 at 1:54 am
My laptop screen shows some kind of vertical dotted lines, with each dots appearing to move one ater the other… like ants moving in a straight line.
in the beginning, there was only one line…now after sometimes, there are 10 and i think, it’s going to increase.
there is also a some part of the screen where it is brighter or paler…its like having a semi transparent-rectangle on the screen – it does not cover it completely but only some part.
my friends told me the pixels are getting damaged. i would like to know how to repair it…is this problem relted to the backlight or inverter?
October 4th, 2007 at 8:23 pm
Hi,
I have 2 problems with my Toshiba Laptop A45-S250, the first is the Screen keeps falling (does not stay up) and i believe it is a hinge problem, therefor i would appreciate it if you could advise on where to get the hinges/ parts and how to install. My second question is the Hard drive just went and again, I need advise on what type of Hard drive to get and how to install.
Thank you for your help
AJ
September 18th, 2007 at 9:39 pm
Qianli Xie,
Sorry, cannot help you with this modification. I doubt that it’s going to work.
September 17th, 2007 at 11:38 am
Hi, I came aross you site and have been reading many very helpful infomation. I have a Toshiba Satellite 4030 CDS with a STN LCD screen and a 2590 CDT with a TFT LCD. The 2590 motherboard is complately dead, while the 4030 is still kicking. I am thinking of using the TFT from 2590 on the 4030. The 2590 has one connector for both video and FL inverter, while the 4030 has separate connectors for video (same number of pins as the 2590) and FL inverter. My questions: 1) Will it work, If I use TFT by connecting video to video connector on 4090 MB, and FL to the FL connector using the 4090 FL cable, but keep the TFT FL inverter board? 2) If the TFT FL inverter board doesn’t work, can I use the STN FL inverter board on TFT?
The 2590 and 4030 have the same connectors (1, 2, 3, and 4 shown on your drawing), except the 3 goes directly to MB on 4030. Both have exactly same video card (Trident Cyber9525 /
2.5MB). 4030 has options for either STN or TFT (model CDS and CDT), not sure if the two models use the same MB or different MB.
I am quite comfortable of taking them apart, but don’t know much about the difference beteen TFT and STN, and how they should be connected.
My special thanks in advance.
Qianli
September 10th, 2007 at 8:36 pm
Grant,
First of all, check connections on both ends of the video cable. Make sure the video cable is making a good contact with the LCD screen and the motherboard. I think it very well could be your problem. If reseating connections doesn’t help, try replacing the video cable.
I don’t think that this problem is related either to the screen or the motherboard. Of course, I could be wrong BUT check connections and the cable first.
September 10th, 2007 at 7:31 am
I have a Compaq Presario V2000 that is having an issue with the LCD only when opening it past about 60 degrees. When it is relatively closed, the image looks perfectly fine, but when opened up wide enough to actually use normally, it fills with horizontal lines and distrotion. I brought it to a repair guy and he said he thinks the LCD and motherboard need to be replaced, but I’m not so sure. Since it only happens depending on the angle, I was guessing it could be just the cable? Am I on the right track, or would you tend to agree with the repair guy?
Thanks for your help!
September 5th, 2007 at 8:07 pm
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