Test laptop screen inverter with a multimeter

Is it possible to test laptop screen inverters with a regular multimeter? I was asking myself exactly the same question many times before until I found this article published by Morris Rosenthal. Apparently, you can test inverters with a multimeter but you have to have the right one, with frequency rated at least 50KHz.

my $20 meter failed to register anything! So I borrowed a better meter from my neighbor, a Fluke 110 true RMS meter. The Fluke specs show it’s rated to 50KHz, which turned out to be critical in the inverter test application.

I’m not sure how accurate this test is, so I will probably find a Fluke multimeter and try it myself. If this test works 100%, it will be very helpful to me.

By the way, some of you may ask what a screen inverter is and where it’s located inside a laptop? I’ll try to answer in a few words. The inverter board is a power supply for the LCD screen and it powers up the backlight lamp (CCFL) inside the LCD screen. When inverter fails, the LCD screen remains dark even after your turn on the laptop.
You still can use the laptop with an external monitor attached to the VGA port but not with the internal screen. The image on the laptop screen will be very dark, almost invisible. The inverter board is located inside the display panel and in most laptops you’ll find the inverter board located right below the LCD screen.
The image below explains how the inverter board is connected to other components inside your laptop. You’ll find more information in this article.

Here’s how you can test the inverter board using a spare backlight lamp.

Basically, you unplug the LCD screen from the inverter and plug in a known good backlight instead. If your test backlight lamp doesn’t light up, most likely there is a problem with the inverter board.

If you plat to test more than one LCD screen, you mgith consider buying this CCFL bulb and inverter tester designed by LCDParts.net. You can find this tester here.

Finally we have the LCD Screen Tester available (LST01 is including a 12V DC Adapter) after months of experiment with many different types of LCD screens. No more guess works! This custom built equipment can help you isolate problem between CCFL Backlight Lamp and Inverter in seconds.

Laptop backlight (CCFL) lamps

If your laptop screen will not light up anymore and you are looking for a backlight lamp (CCFL) replacement, take a look at this site. I just found this website via Google and though it might be useful for you.
I hope you understand this warning.

Purchases of backlights are for professionals who now how to fit correctly, if fit by a novice the LCD panel may show lines or blocks of bad data, or hissing noise from badly soldered joints at the lamp connections. Warning high voltage is applied to the CCFL to create light inside the LCD housing.

Here’s my previous post about replacing the backlight lamp in an IBM laptop. This post might be useful too.

I already mentioned it many times before and I’ll repeat it again. If the backlight on your laptop will not turn on (or it flickers and then goes off) but you still can see a very dim image on the screen, most likely this problem is not related to the backlight lamp. From my experience, in most cases this problem is cause by a faulty inverter board (FL inverter) – the board witch supplies power to the backlight lamp. It is much easier and cheaper to replace the inverter board then replacing the backlight lamp, so try it first.

Replacing laptop backlight

This guide provides some additional information to my previous post about accessing and replacing laptop backlight lamp.
Warning! The backlight lamp is very fragile and can be easily damaged. In order to replace the backlight lamp, you’ll have to disassemble the LCD screen. It’s not easy.

If you have no experience fixing laptops, do not open the screen!
The fourth step says:

Now you can test your newly put backlight. If in any case it doesn’t work, you could try replacing the inverter. Replacing the inverter was just a matter of unhooking a couple of cables.

If you have a problem with the backlight, I would definitely try replacing inverter first. This is much easier then replacing the backlight lamp and there is a good chance to fix the problem.

Laptop Screen Repair - Have a visit of a professional repair company

Being a delicate machine, laptop computers are highly prone to attract a problem that can make it useless. Here the important thing is that how early you get to know the actual problem occurred in the screen of your laptop. The task becomes easier if you are succeeded in determining the actual problem of the laptop. This is because then you can decide that whether to repair the laptop screen or replace it. In case of having a problem in your laptop, you can approach the laptop screen repair company that can help you to find out the actual problem in your laptop sorting out it. There are various steps used in examining the laptop screen problem. Some of them are as follows:


According to some experts, if your laptop computer screen goes completely blank then there can be a problem of the connection on the mother board to the video controller. The monitor is usually connected with pushes into a socket via a ribbon cable. Find out whether the ribbon cable is connected completely. Check the ribbon cable may be loosely connected to the monitor so you should check that also. If you didn't find any difficulty in any of these then there might be the internal problem of monitor and it should be replaced.

In case of having a physical problem in your laptop screen, you can replace it. It is just a matter of eliminating ribbon cable and set of screws to take out the screen. From a huge number of numerous resources you can find online the replacement screen. Find out that all the screws are kept back in the right locations and the ribbon cable is properly replaced.

In case if you notice a problem which solution seems to beyond your reach then you directly refer your laptop screen to a professional and reputable laptop screen repair company that can easily find out the problem and start working on it as soon as possible. As you know laptops are the fragile objects so it i always suggested to go for Repair Company rather than repairing it by your own.

If you notice that there is a physical problem in your laptop screen then it is advised to replace generally or sell them for parts as the cost for repairing the old laptop may not be worth it.

The hardware problems like malfunctioning of the screen or the damage to the screen of laptop are the general issues of the laptop owners. An educated and well trained technical person can easily handle this delicate piece.

These days there are numerous laptop screen repair companies that offer the best possible services to their costumes. They take very short time to repair your PC. According to your requirements, you can choose the right one through the Internet.

INSTALLING MACBOOK AIR DC-IN BOARD

Your Air is thirsty! Keep those electrons flowing and fix your broken DC-In board.

TOOLS USED IN THIS GUIDE

• Phillips #00 Screwdriver

PARTS RELEVANT TO THIS GUIDE

• MacBook Air Magsafe DC-In Board

Step 1 — Lower Case

• Remove the following 10 screws securing the lower case to the Air:
  • Six 2.8 mm Phillips screws.
  • Two 5.4 mm Phillips screws.
  • Two 3.8 mm Phillips screws.

Step 2

• Slightly lift the lower case near the vents and push it toward the rear of the computer to free the mounting tabs.

Step 3 — Battery

• Disconnect the battery connector by pulling it straight away from its socket.

Step 4

• Remove the following nine screws securing the battery to the Air:
  • Four 2.9 mm Phillips.
  • Four 3.8 mm Phillips.
  • One 7.2 mm Phillips.

Step 5

• Lift the battery out of the Air.

Step 6 — DC-In Board

• Remove the single Phillips screw securing the display data cable ground loop to the upper case.

Step 7

• Lift the display data cable slightly for enough clearance to remove the two Phillips screws securing the DC-In board to the upper case.
• Lift the DC-In board slightly and pull its connector straight away from the socket on the logic board.