Backlight and Inverter problems:
Well people, laptop screen repair will be something you will no doubt need info on at some point in your laptop’s life… The symptoms are that the laptop display panel will flicker and then appear to switch off, but if you look closely you can still see a very faint image on the panel, almost like peering through the dark, this is because the backlight isn’t lit.
Inverter boards have been an issue in a lot of makes and models of laptops – this is a very common fault. The inverter board loses proper connection causing the backlight to flicker or just simply fails altogether.
A little info in what we mean when we say ‘Back Light’. Your screen has a fluorescent tube inside it which is just like your normal household tube except for its size, it’s about 1/10 of the size. The tube is attached to a small circuit board via a cable, the circuit board acts like the starter in your household variety. This circuit board is called an ‘Inverter or FL Inverter’, the inverter provides regulated power to the fluorescent tube which lights up the screen.
If the Inverter fails then you appear to have no display, yes and no, the screen is still displaying the image but without light from the tube it only appears ever so faintly.
A lot of repairers will make the assumption that the LCD has failed and tell you about the enormous cost involved in a laptop screen repair to resurrect your beloved laptop, if you’re unlucky this may be the case. Some repairers may even tell you it’s the main board because the video card has failed, they’ll tell you that your laptop screen repair will involve replacing expensive circuit cards.. rubbish.
One way of verifying this for yourself is to connect an external monitor to your laptop’s VGA port and flipping to dual display or external only display, if you get an image then you have narrowed it down to the inverter or the LCD panel.
The Inverter is a small PCB that is generally located in the LCD cover assembly close by the LCD itself. In most cases it can be found either screwed to the case underneath or along side the LCD panel.
You will need to remove the mask assembly which is the plastic outer border around the screen. If you are the type to be a little heavy handed and impatient, then this is not the task for you. Working around an expensive LCD panel is only for people who have the utmost confidence in what they’re doing, the average LCD panel makes up 50% of the overall cost of a laptop and in some cases replacement costs are huge. (Be patient and use minimal force)
Be sure to remove all the screws holding the mask in place, normally expect to see approximately 4-6 screws. In some machines there will be only 2, the mask is also fixed in by snapping type clips that make it fit to the rear cover assembly.
Once you’ve taken that off, you’ll have exposed the LCD and inverter which will both be connected to the LCD harness or wire loom that connects them both to the main board.
1. Connects to the rear of the LCD panel.
2. Connects to the Inverter board or FL inverter.
3. Connects to the main board.
Disconnect the inverter from the harness and from the LCD (the inverter will have a cable plugged into both ends of it) now.. here’s the thing. In a lot of cases your laptop screen repair is just a case of cleaning the inverter pins with some contact cleaner and this will fix the issue for a good while.
The reason is that the pins develop a film on them and lose good connection with the plug that is plugged into them, it’s a good idea to clean the harness plug as well.
If you want to achieve a more permanent fix you will need to apply some Glue (Threebond 1530B) to the end that the harness plugs into (plug number 2, see left image), this will prevent the dirt film forming again on the pins over time.
Once this is done the unit can be reassembled and it should be OK. If you have a faulty inverter that needs replacing the cost will vary from place to place, but study our laptop screen repair guide and use the info to save yourself some money.