Fixing backlight problem by replacing inverter

posted in: Screen | 691

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 (not even very dim image), 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.

Replacing inverter board on IBM ThinkPad T41

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.

Remove screw seals and screws

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.

Remove screw seals on both sides

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.

Lift up LCD bezel

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.

Removing LCD bezel

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.

Remove screw from the inverter

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.

Disconnect inverter cables

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.

Inverter FRU part number


691 Responses

  1. @ Dan M,

    My laptop LCD looked like it was broken glass, but externally it wasn’t. Just the picture has blacked out over a portion of the screen. Thought it was the actual LCD, but when hooking up an external flat panel, I noticed a couple of lines in the picture. Could this be a result of a bad inverter or should I be looking at something else?

    If you still can see a part of the laptop screen it’s definitely not the inverter related problem.
    It’s hard to understand what’s going on without looking at your screen. Can you take a picture, upload it somewhere and send me a link?

  2. I am attempting to repair a toshiba laptop where the LCD screen is very dim. I have replaced the entire LCD which included a new backlight and the inverter board…the issue remains. I suspect the inverter board I rcvd from ebay is not a compatible part but is there any other issue besides the LCD/backlight and inverter board that would cause the LCD to be very dim?

  3. My laptop LCD looked like it was broken glass, but externally it wasn’t. Just the picture has blacked out over a portion of the screen. Thought it was the actual LCD, but when hooking up an external flat panel, I noticed a couple of lines in the picture. Could this be a result of a bad inverter or should I be looking at something else?

  4. @ Ram,
    Sorry, cannot help you with LCD TV repair. I’ve never done it before.

  5. Hi, my question is about an LCD screen (not a laptop per se). It is a sony LCD TV. The power supply unit and one of the inverters had transistors blown out due to a power supply surge. I am in Egypt where the current is 220v. I can order parts from ebay from the US but I know the power supply there is 110v. When I do that, I assume I have to connect the power supply via a transformer (220–>110) but do I have to also change BOTH inverter panels (not just the one that is blown out) and would the rest of the screen components get the right voltage power supply?

  6. @ Ken,

    Screen backlight works but the screen is white. Replaced the LCD Screen and the cable without any luck. If I connect to an external monitor, the image is fine.

    If new LCD and cable didn’t fix the issue, probably this is motherboard related failure.

  7. Screen backlight works but the screen is white. Replaced the LCD Screen and the cable without any luck. If I connect to an external monitor, the image is fine.
    thanks

  8. @ Junho,

    I have a gateway mt3705 and the screen went dark. You can see it slightly with a flashlight. I tried replacing the inverter board but it did not fix it. Then i tried booting it with the inverter board unplugged and the same situation persisted (i saw a dark screen that i could see dimly with a flashlight. Does this mean my replacement inverter is faulty or could the problem lie elsewhere?

    If new inverter didn’t fix the problem, it’s likely you have a problem with the CCFL bulb inside the screen. It means the LCD screen has to be replaced.

  9. @ Nevadaleigh,

    Did you have a chance to test your laptop with an external monitor? I assume the external image works fine?
    Also, when you turn on the laptop you should have the eMachine logo on the screen. Is this logo shifted too?
    If external image appears to be fine and the eMachine logo is shifted too, probably this is LCD screen related problem.
    You can try replacing the LCD screen yourself.
    A new screen for eMachines em350 laptop is about $60-70 on eBay.
    It shouldn’t be very difficult to replace. Just remove the screen bezel and unplug the old screen.

  10. I have a gateway mt3705 and the screen went dark. You can see it slightly with a flashlight. I tried replacing the inverter board but it did not fix it. Then i tried booting it with the inverter board unplugged and the same situation persisted (i saw a dark screen that i could see dimly with a flashlight. Does this mean my replacement inverter is faulty or could the problem lie elsewhere?

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