Screen replacement; loss of brightness control
Congratulations, you've found a replacement screen online to replace the broken one in your laptop or tablet computer. You're so pleased that you've managed to perform this repair alone, but something isn't quite right.
When you use the hotkey brightness controls on the keyboard, you cannot adjust the brightness of the screen anymore. It maybe that your screen is stuck in low brightness or full brightness but anyhow, you can see that you can't adjust that.
So what's happened? Well, we'll explain.
The brightness controls on your keyboard, are two buttons, up and down. When you push one of these buttons, a piece of software usually called a hotkey driver will realise the buttons are being pushed. This hotkey driver will then talk to the screen to ask the screen to adjust the backlight brightness. It's a little more complex than that but you get the jist.
What's happening here is the hotkey software is now unable to talk to the new screen. There are two main reasons for this, the first being that the display driver for the new screen is now incorrect as you've changed the screen (most likely for a different model or brand), or that the new screen has updated software that the hotkey driver does not recognize. Yes, although your screen is hardware, it does also have software loaded onto it known as EDID.
Here are some steps you can take to rectify the situation:
1st and easiest option
Remove the monitor.inf (we're going to remove the current monitor / LCD driver from the system and load a new, hopefully more compatible one). You'll need to head off to your Windows Control Panel, and find the Device Manager which is usually situated in the Computer Management utility, or can be found by right clicking on My Computer and choosing "Manage".)
You'll see a long list of devices that are attached to your laptop or tablet, one of them will be called "Monitor". Expand Monitor and double click on the installed monitor driver, you want to choose to uninstall it and delete the driver if you have that option as well so that it cannot automatically reload itself again. This last step is important, you don't want Windows to just reload the same driver again, which is what it will do.
Reboot the computer and check the brightness controls again.
Still not working? Okay we're going to get a bit more in depth now :)
You want to go into Windows and uninstall the display driver software; this can be done by going to the Control Panel, choosing Add/Remove Programs (or Uninstall a program on newer versions of Windows). You'll see a long list of your installed software. Scroll down the list until you find something that is called Display Drivers. You may see the words Intel or NVidia as well. Right click and uninstall this software. Reboot the computer and check the hotkey software again.
Still not working? Okay we're going to get really in depth now :)
Now we're going to go to the laptop or tablet manufacturer's website, and we're going to search for options to update the BIOS, sometimes called flash or reflash the bios on the laptop. There's usually a downloadable utility that may go on a pendrive (USB stick) or a CD disc. We want to follow the instructions from the manufacturer to update the laptop's BIOS. This is an advanced feature that you should not undertake if you're unsure as it could leave the computer unusable. You may want to speak to the manufacturer to ask for assistance. When that is done, you want to check also to see if they have a newer version of the hotkey software, sometimes called utility software or tools. If there is a downloadable package for the hotkey/utility/tool please update this as well following the manufacturer's instructions.
Final option if things still aren't going to plan.
4th option: transfer the screen EDID
Laptop and tablet screens use something called EDID which is a VESA standard software loaded onto the screen. The screen will talk to the laptop via these drivers that you've been trying to update above, a bit like we'd talk to each other. Hi, Hi. What are you? I'm an LG Philips screen. Thanks, what resolution are you? I;m 1366x768. Thanks. And so on. So the laptop will "identify" the type and spec of screen fitted. This communication process is the same for the brightness control, however if the screen EDID version is newer than the hotkey software, it's possible the hotkey software will no longer be able to talk to the screen (correctly).
In these cases it is often possible to copy the EDID from the old screen to the new one, however this involves something called an LCD burner. An LCD burner will allow you to copy the screen EDID from the old to the new and so the laptop will believe the old screen is still fitted. Although you need a cable to connect to the screen and a computer, which we cannot supply, we have provided a download of some EDID burning software in this article.
EDID_Writer.zip (135.97 kb)
So, that's about it, there's not many more options after this other than perhaps trying to set the brightness controls in the BIOS setup (accessed usually by pressing an F key on the keyboard when the laptop starts), or by trying the Windows Power Management settings. There are some 3rd party utilities you can download which claim to adjust brightness controls but these are only useful for dimming the screen and not generally as good as the working hotkey controls.
We hope this has been useful information and good luck with your brightness controls =D