Screen inverter replacement. Fixing laptop backlight problem.
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.
Entry Filed under: Replacing Screen Inverter
311 Responses to “Screen inverter replacement. Fixing laptop backlight problem.”
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Pages: « 32 31 30 [29] 28 27 26 25 24 23 22 … 1 » Show All
July 9th, 2008 at 9:52 am
How come there’s always ONE screw which is torqued too tight to remove easily?
And how do you get it out if it’s stripped?
July 5th, 2008 at 3:14 pm
yes if you can see the image dim on screen and perfect on an external monitor then it is your back light.
June 26th, 2008 at 7:52 am
Hi all,
I have a Dell Inspiron 6000
I had the following problems in this order:
- Flickering
- Hot spot in right bottom corner
- Now light for a few mins - then gone
- Faint image
- Fine on monitor
I am ordering a new inverter - but anybody experience of the spot?
Thanks all!
June 23rd, 2008 at 1:36 pm
netshark993,
In most cases replacing the inverter board would fix this problem but not all the time. In some cases this problem could be related to the backlight lamp (CCFL bulb), the video cable, or even the motherboard.
The next troubleshooting step would be testing the laptop with another working LCD screen or at least another working backlight lamp, as I explained in this post.
If you don’t have any spare parts, you’ll have to guess.
June 23rd, 2008 at 11:41 am
i have a compaq presario 2100 i have tried replacing the inverter… still dim screen. when i hook up an external monitor it has no signal… the screen is dim on the laptop tho.. i get a picture when looking very closly… what could be the problem?
June 19th, 2008 at 8:54 am
Enigmaniac,
Yes, it’s possible. I’ve seen that before.
In the comment 280 you said:
The image is still on the laptop screen but it’s very dark (no backlight), right? That means that the LCD screen is getting data signal from the motherboard / video card but the backlight lamp is not getting power. Take a look at this picture. Display diagram
What could be wrong?
1. The backlight lamp is bad.
2. The inverter board is bad and it will not provide power for the backlight lamp.
3. The video cable is defective and because of that the inverter/backlight is not getting any power.
4. There is something wrong with the motherboard and it will not provide power for the inverter/backlight.
Even though the external monitor works fine, the problem still could be related to the motherboard.
June 19th, 2008 at 8:35 am
Guys, I had the same problem with my laptop as well and had a working temporary solution (still gives me a problem sometimes)
I had an IBM x20 with screen problem. Bought a new inverter and new screen and just doesn’t show any picture at all after I replace it.
Apparently there are some setting or option that determine if your computer recognize your screen properly after you fiddle with it residing in its own proprietary or shared ram. Whichever one it is you need to take your charger off and take out your battery as well. Then leave your computer for about 30 seconds before turning your computer back on to make sure the charge in memory has been cleared /depleted.
This solution works fine for me and now I had my x20 shining like new again. The screen still blink sometimes maybe indicating that I need to get a new inverter board. I actually still using my old inverter because it is not dead yet. The replacement is already waiting besides me.
Unless your cable breaks (you can check it visually) or your connector very loose (no idea how to make certain) then you don’t need a new cable. Just reseat the cable properly then clear your memory using the step above and it should solve your problem. It may take several attemps though…
Good luck
ps: That’s why you pay for professional to fix your computer, saves you a lot of hassle plus you have someone to blame if it doesn’t work…..hahaha
June 19th, 2008 at 2:34 am
Hi again,
This is related to my previous post number 280.
Thanks for your reply!
The reason I think the motherboard is working okay is because I’ve connected an external monitor and it works fine. Can the motherboard be faulty even if the external monitor is working okay?
Please correct me if I am wrong.
Thanks again!
June 18th, 2008 at 10:02 pm
Enigmaniac,
This problem could be related to:
1. Screen inverter.
2. Backlight lamp (CCFL lump) inside the LCD screen.
3. Video cable.
4. Motherboard.
I think the magnetic lid switch would be the last think to blame. I’ve never seen a failed magnetic switch. Maybe I’m lucky.
You should ask the technician how he came to that conclusion. If he tested your laptop with another known good LCD screen and inverter, most likely he’s right. Also, this problem could be related to the video cable.
If you have a magnetic lid close switch, you have to have a magnet somewhere inside the LCD panel. This magnet activates the switch when the display is closed. Find a small metal screwdriver and move it slowly along the LCD screen bezel. The screwdriver will be attracted by the magnet. Now when you know where the magnet is located, close the display and find the location of the magnetic switch.
Try reducing the LCD screen brightness as David did in the comment 279. I guess you have a different key combination for a HP laptop. On my HP Pavilion zv5000 I use Fn+F7 to reduce the screen brightness and Fn+F8 to increase the brightness.
The only reliable way to narrow down the problem is installing another inverter and LCD screen. Talk to your technician and ask what he did. If he tried that already, you may try replacing the video cable. If replacing LCD, inverter and video cable will not help, apparently you need a new motherboard.
June 18th, 2008 at 9:36 pm
David G,
Here’s my guess. If you are getting the same problem with another inverter board, most likely it’s not related to the inverter. Apparently, the backlight lamp is getting old but it still works when you lower the voltage (reduce the screen brightness). I just tried reducing the screen brightness from 7 bars to 5 bars on my ThinkPad T42 and looks OK, it’s still usable.