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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October 2nd, 2009 at 11:51 am
Hi, me again
I did, I disassambles the lcd panel, before wrote my first post, I bougt the inverter toom but i can’t find the conector.
I was thinking Weld the wires in inverter’s 7 pins conector , but I need the color order of each wire
do you know where can I find it?
thanks a lot to answer
October 1st, 2009 at 6:09 pm
Felipe Valero,
If the cable and connector are damaged, I would replace the video cable.
This article will help you to remove the display panel. And you know how to disassemble it, right?
October 1st, 2009 at 5:59 pm
Colin C,
I doubt it. From my experience, magnetic switches do not fail very often.
Is it possible that you have a faulty switch? Yes. Is it likely? No.
Most likely you have a bad backlight lamp inside the LCD screen.
If you don’t want to buy a new screen without confirming the backlight failure, you can buy a new backlight lamp and test the laptop as I explained in this post:
http://www.laptoprepair101.com.....in-laptop/
1. Find a test backlight lamp.
2. Confirm the backlight lamp failure in your LCD screen.
3. Buy a new screen and replace it.
September 29th, 2009 at 9:04 pm
Replaced the screen inverter; didn’t fix.
However, noticed stimulating magnet of lid close switch gets screen to flash on temporarily? Do I just need to clean/replace the lid close switch?
September 29th, 2009 at 1:07 pm
Hi, my laptop inverter was burn (wather accident) I have a new one
TBD281NR-1 E168066 the laptop is a hp compaq 6720s
but the 7 pin conector was very damaged and the wire too, now i want to fix the wire conector but i have not idea about the color oreder of the wires.
I was googlin but I don’t found any diagram
hace any idea???
thanks a lot.
September 20th, 2009 at 11:28 pm
Bernard,
1. Stuck lid close switch.
2. Bad video cable.
3. Something wrong with the motherboard.
September 18th, 2009 at 12:59 pm
Rich Lang,
Apparently you had a faulty backlight lamp inside the screen. The backlight lamp and inverter have very similar failure symptoms. If you have no test equipment, you’ll have to guess which one is causing the problem.
I’ve done it many times before and it worked for my just fine. The screen bezel is pretty flexible and if you work slowly everything should be OK.
September 18th, 2009 at 12:45 pm
Replacing the inverter card in my ThinkPad T42 did not solve my blank LCD screen problem. Replacing the entire LCD panel did solve the problem. My “blank screen” had symptoms similar to the first two listed at the beginning of this web page. But it was the LCD panel itself, and not the inverter that was the culprit.
My “blank screen” was triggered by the LCD brightness setting–the higher the LCD brightness, the sooner the screen would blink off. Further details to assist in troubleshooting a blank screen on a ThinkPad notebook and additional points and information helpful in replacing both an inverter card and a LCD panel can be found at
http://richlang.home.pipeline.com/TP-LCDswap.html
I do disagree with the statement in the main body above, “This notebook allows you to replace the inverter board without removing the LCD bezel completely.” Attempting to change the inverter card without completely removing the bezel (a) will make it very difficult to unplug the inverter card because you don’t have room to work on it AND (b) you risk distorting the plastic edge of the bezel where it remains attached to the cover, with the result that the bezel does not fit perfectly to the cover when you try to put it back together again (happened to me).
To cj2600, Thanks for the info. It helped me understand how to tackle this job.
September 15th, 2009 at 2:33 am
Hi,
I have a working screen and a working inverter, though same symptoms. Any idea what this could be?
IBM A31 laptop.
thanks,
Bernard
September 2nd, 2009 at 4:43 pm
Thank you so much! Information really helped!