Do you have a problem with the backlight on your laptop? If yes, you are not alone, that’s one of the most common laptop problems. In most cases the screen inverter is the culprit. Here are some LCD screen backlight failure symptoms that could be related to a bad inverter board:
- Laptop boots as usual but after some time the screen blacks out. You still can see an image on the screen but it’s very dim. You might even use a flashlight to see it better. Sometimes the backlight comes back for a while but then goes off again. In some cases you can turn the backlight on if you tap rapidly on the lid close switch.
- The screen always stay black and the backlight never comes on but you still can make out an image on the LCD. It’s dark, but the image is still there.
-In some cases you might hear a buzzing noise coming from the area where the inverter board is located, it’s on the bottom part of the display assembly.
NOTE: if you cannot see an image on the screen, most likely you have a different problem and there is nothing wrong with the screen inverter.
Other related articles:
Laptop has bad video on the LCD screen. What is wrong?
Notebook display assembly diagram. How image appears on the screen.
How to troubleshoot and fix laptop video problems
How to replace laptop backlight lamp (CCFL)
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.
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.
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.
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.
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.
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.
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.
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.
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November 18th, 2009 at 2:58 pm
Barrera,
You should have mentioned the laptop model. There are tons of different inverters out there.
November 18th, 2009 at 2:55 pm
Do you know how much the replacing part “the inverter” cost?
November 18th, 2009 at 2:19 pm
trav3ller,
Your description doesn’t sound like a problem with the inverter board at all. If you can see the screen, even though there is no image on it, the inverter is working properly.
) but fixed your laptop by reseating the video cable connection.
It’s possible that your technician ordered a new inverter board “as a precaution” (that’s how you get parts for test
November 17th, 2009 at 4:27 pm
Just had an MSI EX300 repaired under warranty.
The service report said the inverter board had been faulty and was replaced.
My laptop had different sypmtoms though, the screen was actually a dull grey/white so it looks like the backlight was working ok but no image appeared.
But as you described the laptop boots up ok and runs an external monitor just fine.
Thanks for providing the info at least I’ll know what to look for in the future
November 14th, 2009 at 2:27 pm
Johnerything,
If you can fix the problem by moving the screen, most likely it’s either bad connection or faulty video cable.
1. Check connections between the video cable and LCD screen, inverter board. Reseat them just in case.
2. If you have the lid close button, make sure it moves freely. Try tapping on the button and see if it light up the screen.
3. Try replacing the video cable, it could be bad. It’s not a common failure, but possible.
November 14th, 2009 at 2:22 pm
Yes, I have the exact same problem. Screen goes DIM but you can still see everything. Move the screen back and forth rapidly brings it back but now even that doesn’t work.
November 5th, 2009 at 11:43 am
Bill,
Yep, sounds like the lid close switch button works properly.
Usually, this indicates a problem with the inverter board or backlight lamp.
It’s hard to tell what is causing the problem. I guess it’s possible that your new inverter board or backlight is not good. I’ve seen is happening before.
If you know that inverter and backlight are good 100% then you have a problem with the motherboard. Apparently, it’s not providing power to the inverter/backlight (just a guess).
Sorry, I cannot give you a better answer without testing the laptop with known good parts.
November 5th, 2009 at 11:38 am
Wagner,
This is not related to the inverter. The screen is still bright (even though shows wrong colors), so the inverter and backligth lamp work properly.
This could be:
1. Bad connection between the video cable and motherboard or LCD screen. Try reconnecting the video cable on both ends.
2. Bad video cable. Maybe there is a shorted wire inside the video harness. Try replacing the video cable.
3. LCD screen failure. Replace the LCD screen.