Troubleshooting backlight failure . My customer complained that the laptop LCD screen is black but the laptop works with an external monitor. Here are my steps for troubleshooting this laptop with the backlight failure. First of all, I tested this laptop with an external monitor connected to the VGA port and the external monitor worked absolutely fine. I was able to get crystal clear image on the external screen even though the internal screen didn’t light up. If the external screen works fine, then most likely there is nothing wrong with the video card. Notebook display assembly diagram. After that I took a closer look at the laptop LCD and noticed that the screen is not completely black. The laptop screen still works but the image is very very dull, you barely can see it. It means that the screen still gets data signal from the video card, but for some reason the backlight lamp doesn’t work. From my experience I know that this problem can be related the lid close switch, faulty inverter board or bad backlight lamp. I checked them one by one. If you have a similar problem, make sure the lid close witch moves freely. The lid switch is a small button located close to the LCD screen. This button triggers the hibernation or sleep mode when the screen is closed. If the lid close switch is dirty, it might get stuck inside the laptop case and cut off the power from the inverter board. The inverter board works as a power supply for the backlight lamp and if there is no power coming to the inverter board, the backlight lamp will not light up either. A manual can describe a collection of guides, or just a single guide. An example service manual for a Dell laptop might include a dozen guides. Have you come to this webpage looking for Toshiba laptop service manuals? In the same vein as in my driver guide, I’ve started. 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. ![]() Directory-list-lowercase-2.3-small.txt Copyright 2007 James Fisher This work is licensed under the Creative Commons Attribution-Share Alike 3.0 License. Select your country to continue on HP.com. United Kingdom United States. No other company offers as complete a technology product. This laptop came for repair because of the LCD screen backlight failure. My customer complained that the laptop LCD screen is black but the laptop works with an. Latest trending topics being covered on ZDNet including Reviews, Tech Industry, Security, Hardware, Apple, and Windows. ![]() In my case the lid button worked properly, it didn’t stuck inside the case. When I was pressing on the button very fast, I was able to light up the screen but only for a fraction of a second. The image wasn’t bright and it had a pinkish tone. A pinkish tone usually indicates a problem with the backlight lamp, not the inverter board. Even though I suspected the backlight failure, I decided to test this laptop with a new inverter board just in case. The screen didn’t light up even after I replace the inverter board. So, I was right, this problem is not related to the inverter board. ![]() Finally, I disconnected the screen backlight lamp connector from the inverter board and connected my test backlight lamp (I removed it from another cracked screen). You can find a new backlight lamp on e. Bay. Try to find a backlight with the connector already attached to it, so you can plug it into the inverter board. Make sure the connector on the backlight lamp is similar to the connector on your LCD screen. As soon as I turned on the laptop, my backlight lamp lighted up. Yep, that’s the problem. The laptop screen has a faulty backlight lamp. Here’s another laptop with backlight failure. This laptop video fails in a little bit different way. In this case the backlight lamp hasn’t failed completely. The laptop starts with video on the screen but the background has reddish tone, the screen flickers and it makes noticeable buzzing noise coming from the backlight and inverter area. After a few minutes the backlight turns off by itself and the buzzing noise stops. When the backlight is off, the image on the screen is still visible but it’s very dark. I removed the screen bezel and connected my test backlight lamp. My test backlight works absolutely fine. The lamp doesn’t flicker and there is no buzzing noise. So, this laptop needs a new backlight lamp. Basedirectory List 2. Small . However, it looks like you listened to. Fixing bad video on LCD screen. 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. Example 1. Here’s a picture of Satellite M5. 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. As soon as I applied some tension to the screen it changed the pattern. Some horizontal lines appeared in the middle of the LCD. 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 M6. 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. 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 5. 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. 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. 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 5. To fix the problem, I’ll have to replace the board. It wasn’t the LCD screen problem. 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. Example 6. Here’s another laptop with a bad LCD screen. This time it’s a tablet PC. 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. Here’s the difference. When I torque the screen, the image appears but it’s distorted with some horizontal lines running across the screen. After a few seconds the 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. 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. On the following image only the left side of the screen is working properly. This problem is caused by faulty LCD screen. 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.
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October 2017
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