In this post I explain how I test the LCD screen inverter board in a laptop computer.
The screen inverter failure is very similar to the backlight lamp failure. In both cases the screen gets very dark and the image on the screen becomes very faint, barely visible under a bright light.
If you suspect the inverter board failure, I know only one reliable way to test that. It’s either replacing the inverter board with a known good one and see if it works, or connecting a known good backlight lamp and see if your presumably bad inverter lights it up.
In most cases I go with the second method – testing the laptop with a known good backlight lamp. Why? Because backlight lamps are pretty much universal. The same backlight lamp will work with many different inverters as long as they have matching connectors. I’ll talk about these connectors later.
The inverter board is located inside the display panel under the LCD screen. In most laptops you can access the inverter board if you remove the LCD screen bezel. The inverter board has connectors on both ends. The left side of the inverter is connected to the LCD cable. The right side of the inverter is connected to the backlight lamp which is mounted inside the LCD screen. Check out this display diagram.
To make sure that inverter board is getting power from the motherboard (via the LCD cable), you can test it with a multimeter. In my case I connected the “+” lead of the multimeter to the pin 1 on the connector and the “-” lead to the ground trace around the screw hole. I got about 19.4V DC on that side of the inverter, so it’s getting power from the motherboard.
WARNING! If you accidentally short something on the inverter while testing it, you can damage the inverter or even the motherboard. Proceed on your own risk! Not sure? Don’t do that!
So, the inverter is getting power from the motherboard, but the screen is still dark. Apparently, it’s either bad inverter or failed backlight. Let’s test it with a known good backlight.
Here’s what I’m going to do:
1. I will unplug the LCD screen from the right side of the inverter. Basically, I’m unplugging the LCD backligth lamp which is located inside the screen.
2. I will plug in my known good backlight lamp which you can see on the picture below. Please notice that my test backlight lamp is shorter than the screen, but for the test purpose that’s OK.
Results I’m expecting:
1. If my test backlight lights up, the backlight lamp inside the screen is bad and there is nothing wrong with the inverter board. If that’s the case, you’ll have to replace the LCD screen or replace the backligth lamp (which is not easy at all).
2. If my known good backlight lamp stays dark after I turn on the laptop, most likely we have a faulty inverter board. If that’s the case, you’ll have to replace the inverter board and it’s relatively easy.
There are two different types of backlight connectors, you can see them on the picture below. The top one (big) is not as common as the bottom one (small). I do most of my test with a backligth lamp which has a small connector.
IMPORTANT! If you decide to buy a new backlight lamp for test, you have to make sure that the connector on the lamp matches the connector on the inverter. Very often backligth lamps are sold without any wires attached. If you plan to use this backlight as a test equipment, you’ll have to find one with wires as I have on the picture 3.
You can buy a cheap backlight lamp with wires here.
Finally, when you ready to test the laptop, unplug the LCD screen from the right side of the inverter.
Plug in your test backlight lamp and turn on the laptop.
In my case, the backlight lamp lights up, so the inverter board works properly.
Check out my previous post about troubleshooting laptops with backlight failure.
If you find this article useful, please consider making a donation to the author. Thank you!
May 11th, 2009 at 7:39 pm
Hi CJ.
I love your blog, there’s a lot of tips that i’ve used to repair some laptop, thanks for that.
I have a problem with a laptop, when I turn it on, the screen is very dark, with one very very soft image, at first, I think it was the lcd inverter, I’ve changed it with no success, the screen keeps black, I’ve read your post and followed the steps to test the inverter with another backlight, when I do this nothing happens, the lamp doesn’t turn on, what this could be??, maybe the motherboard isn’t sending power to the inverter to turn on the lamp??please, I need your help. Thanks.
Note: When I plug an external monitor there’s no problem, video is ok.
P.S. Sorry for my english
May 11th, 2009 at 8:37 pm
Israelinkvm,
Does it look like there is no backlight at all or it looks like the backlight works but the brightness is very low?
May 12th, 2009 at 4:20 am
Like I said before, I’ve tested with another backlight but it doesn’t light up, the brightness is ok.
May 15th, 2009 at 6:33 pm
hi,what should be the voltage settings for multimeter if I would test the inverter?thanks.
May 17th, 2009 at 3:43 am
Hi,
Thanks a zillion for this article. I had a dim LCD screen laptop. By following some of the instructions I could zero in on the problem. I tested out the DC part of the inverter board, I was getting around 15V, but I tested the AC section of the board (the other end feeding the backlight) on a multi-meter and I did not get a reading. So i could figure out that the inverter board was the problem. Replaced the inverter board and LCD screen lights up. Gave me a lot of satisfaction, kudos mate … great job of writing up the article in a very lucid manner.
May 17th, 2009 at 8:28 am
chakra,
That means the inverter is getting power from the motherboard.
I don’t think that you can test the AC output with a multimeter, at least it never worked for me. I tried testing the AC output on a working laptop, just to find out what readings I should expect but as soon as I connect the multimeter, the backlight shuts off. That’s way I suggest testing a faulty laptop with another known good backlight lamp.
I’m glad it worked for you.
May 17th, 2009 at 8:34 am
inquirer1,
When you test voltage coming to the inverter from the motherboard, you should set your voltmeter to test DC in the range somewhere between 0-50VDC.
I think you should expect readings somewhere between 10VDC-20VDC, it depends on the model.
You cannot use the voltmeter to test the AC output.
May 17th, 2009 at 8:39 am
Israelinkvm,
If the screen has no backlight and replacing the inverter with backlight lamp doesn’t help, apparently there is a problem with the motherboard.
Also, this problem could be related to the video cable, but it’s not a common failure. If you have the lid close switch – a small button which turns off the light on the screen when you close the display, make sure this button moves freely. A dirty lid close button might get stuck inside the case and the laptop “thinks” that the display is closed even when it’s open.
May 19th, 2009 at 6:38 am
You can also use a cheap electricians amp-meter that measures induction via the magnetic field to test these. The coil creates a pretty hefty magnetic field.
May 19th, 2009 at 7:39 am
Bodinator,
Yes you can but I believe you’ll get positive readings only if both the backlight lamp and inverter are in a good working condition. The magnetic field will be created only if the inverter is loaded, right? But what if one of the parts is faulty and there is no magnetic field around the inverter? How can you tell if it’s a bad inverter or backlight lamp?
May 25th, 2009 at 12:49 am
I have a Dell Inspiron 1501 laptop where the LCD goes black at apparently random times after being turned on. The computer remains on and apparently continuing whatever functions it was working on, but the monitor is dark. Sometimes it will only stay on for a minute after bootup and other times I can use it for 10-20 minutes before it goes dark. I am pretty confident its not a battery issue and it shouldn’t be a hibernation or sleep issue, since I am always actively using the computer when this happens.
I’ve seen other people on the internet with similar laptop complaints, but I can’t seem to pinpoint a common cause. Could this be a bad LCD inverter?
June 1st, 2009 at 8:48 am
To AJ Simkatu (comment 11),
If you still can see a very faint image on the screen even though the backlight is off, most likely your problem is related to the screen inverter. If you replae the inverter but the problem is still there, apparenlty it’s a faulty backlight lamp.
Again, sounds like either bad inverter or backlight.
If you have to guess, I would try replacing the inverter first.
June 1st, 2009 at 5:34 pm
I have a screen thats is really bright and everything is washed out, Mouse pointer is only visible if it stops moving and fades in and out slowly when you stop and start it.
Laptop works fine through a VGA connection.
This a screen problem?
June 1st, 2009 at 8:50 pm
JH,
Yep, to me your description sounds like a problem with the LCD screen.
June 3rd, 2009 at 1:37 am
HI,
I’ve changed a broken screen of my laptop, but i get a dark screen with faded images whenever i turn it on ,i tried to test the inverter input and i got 1.85 v at start then it goes down to 0.48v after a few seconds ,the cables and connectors are all well connected and when i connect my notebook to an external monitor it works fine, can u tell me plz whats the problem and how can i solve it, thank u
June 9th, 2009 at 6:43 am
“”Yes you can but I believe you’ll get positive readings only if both the back light lamp and inverter are in a good working condition. The magnetic field will be created only if the inverter is loaded, right? But what if one of the parts is faulty and there is no magnetic field around the inverter? How can you tell if it’s a bad inverter or back light lamp?”"
An inverter takes a (relatively) high amperage low voltage signal and turns it into an extremly high (KV range) low amperage (mA range) signal. There are 4 failure points; CCFL, Inverter, Cable, and Mobo. Couple of things to keep in mind:
A: If the CCFL fails it will not load the inverter, so no mag field.
B: If the Cable fails (pretty much it can only fail one way), no voltage = no mag field.
C: If the inverter fails, you may or may not get voltage; if the CCFL is loading the inverter and the inverter is not producing enough voltage you’d probably not get a mag field.
D: If the mobo fails, no voltage or not enough.
Say the unit is DOA and you *THINK* it has a backlight issue, the ampmeter is the 3-second solution to see if you’ve got a functioning inverter. Most laptops go through a power-post procedure similar to a desktop psu and will load the inverter if it passes even if the unit fails to post.
I like the idea of ordering a $15 CCFL and using that to test; I hadn’t thought of that before and come to think of it to test this properly you’d need an assortment of CCFL’s and cable converters. It’d be easy to build a professional soluton from epoxy, wood, 2×3’s, plexiglass, some screws and a label maker.
I do keep a spare 12” LCD on hand, as well as a 20” chassis with an inverter hooked into it. You can load a high-end inverter with a low-end LCD ccfl. The problem with either is if you use a 12” LCD CCFL to test a 16” inverter anbd the 16” inverter is ok producing voltage for as 12” ccfl but not a 16” ccfl you wouldn’t know it until you plugged it into the 16” ccfl.
June 10th, 2009 at 11:28 am
Hello i have a fujitsu siemens with geforce 6800 and my screen show many pink spots and when i twist the computer it get better, but on external monitor the image is always very good.
Do you have an ideia of what could it be? Many thanks
June 11th, 2009 at 4:03 am
sounds just like my laptop turn it on goes for about 1 or 2minute then goes black. computer is still working in want program it is in . when i turn it on the screen has a pink tinge to it.
June 12th, 2009 at 8:55 am
Hi CJ,
Thank you so much for your thorough review! It is very helpful!
My Inspiron 1520 has recently had random backlight failures in
which the screen goes dim. It always re-lights if I sleep and resume (or whenever I start an external monitor). The backlight stays on for a few minutes and then fails again.
Does this sound like a failing inverter or could there be other explanations?
Thanks again!
Cameron
June 18th, 2009 at 3:53 pm
I had computer in rain. Screen is still quit legable with some distortion of images. I ruled out motherboard and video card. So I thought it was the screen. I ordered new one hooked up the inverter to backlight backwards. Some sizzle then went dark. I then installed connector properly and screen lit up fine, but image is still garbled. Did I ruin new screen or ids the problem lcd cable. Thank You.
Dave
June 23rd, 2009 at 9:18 am
I have an issue with my laptop that I think is connected to the screen inverter. all the white colors (only true white, off white is fine) turns into this pink color with white lines and all the black (True black) turns into this green flashing color. if I move the screen about it some times gets better or worse but sadly my screen case is broken so I have to prop it up against pillows. Is this simply an issue with my screen inverter or with the wires, and is it fixable or not? can you recommend a good repair shop is Boise, ID that won’t tell me to get a new laptop? thank you for your time.
June 24th, 2009 at 4:48 pm
What if the screen comes on for a while then goes out. It does the same with an external monitor
June 26th, 2009 at 8:43 pm
i just split the soymilk on my laptop, while i didn’t get a chance to shut it off, and right now, when i open my laptop, the screen is very dark, but i can still see a little,very very dark, do you think it is inverter problem or it is motherboard’s….
June 27th, 2009 at 10:17 pm
moteldanny,
There is no way you can tell without testing the laptop with a known good inverter board. If you spilled milk on the keyboard (not display), probably your failure is related to the motherboard.
June 27th, 2009 at 10:38 pm
Brian,
Can you boot to the desktop or it fails before the laptop finish loading Windows?
Enter the BIOS setup menu and wait. Does it fail in BIOS?
June 27th, 2009 at 11:36 pm
Nathan P,
Your problem is not connected to the inverter board. The screen is bright and you can see it, so the inverter works properly.
I think it’s either bad video cable or LCD.
You said, you can make it better or worse if you move the screen. I think your problem is connected to the video cable. I would try replacing the cable first.
June 29th, 2009 at 8:54 am
I have a Fujitsu LifeBook C Series computer, and it is having intermittent problems, that I believe to be in the inverter. I’m looking for a opinion from more experienced folks. Every once in awhile (usually after having been off for a while), the screen will go out, literally. It will freeze the image on the screen and warp it while it goes out. Simply moving the screen on its hinges fixes the problem and puts the LCD right back where it should be – in perfect looking condition. It may take up to 3 or 4 hinge movements before it finally comes back. I’ve never not been able to bring it back. The inverter is located directly under the LCD.
June 29th, 2009 at 8:55 am
also, it’s pretty worthy to note that the inverter itself gets very warm while in use. I checked its temperature and it was up to 102 Fahrenheit, I’m thinking that is abnormally high for inverters.
June 30th, 2009 at 1:54 pm
It’s got me beat and I hate that. Any ideas would be appreciated. Daughters laptop she says thinks her brother might have dropped it, no visible damage. Screen very dark. Changed power settings to never turn off screen when on mains. Then changed bios to default. Additional monitor works fine and is cloneing laptop screen. Gets 15v from motherboard so changed inverter. Next changed backlight. Both backlights have 16k ohms resistance which seems reasonable. Updated virus definitions and ran full scan. Can’t think of any logical reason why it doesn’t work? Can you help me be a good dad?
July 1st, 2009 at 4:44 am
my notebook is toshiba L300-P502 got one problem, i cant think about what happen. when i pluged-in ac adapter while the battery full charged. the screen brightness might gone up and down flickers itself. until i turn off the ac power, the problem gone. what is the problem?
if i plug-in ac only sometime it may damn dark and bright dark and bright. the damn dark and bright dark and bright gone if i press Fn+F6 / F7, sometime i on for 4 hour without a problem. even the battery installed. damn notebook just 1 month old, my birthday gift after saving for 2 month to buy it.
July 3rd, 2009 at 1:10 am
sir i have a dead laptop i want to use its lcd on my pc how can its posebale
July 10th, 2009 at 5:03 pm
hello CJ,
I have a Toshiba m45 laptop. The screen has a native resolution of 1280 X 800. When the laptop is powered on, it only displays a 1024 X 768 resolution. This also happens in setup screen also. The image occupies the top left of the screen with the rest being black. I’ve tried connecting a known working lcd screen with same results. When an external monitor is hooked up it functions with a 1280 X 1024 resolution which is the native resolution of the external monitor. Therefor i presume that the on-board video works. Could this be a bad cable or bad on-board video?
Any suggestions would be greatly appreciated.
thank you!
JakeTT
July 16th, 2009 at 7:59 am
Hi, I have a Gateway 7510GX the screen back lite flickers, dims and often goes out, you can still see whats on the screen when it goes out. I was thinking that it was the inverter bord. I dont have a good board to test it with. What do you think?
Thank you for your time, Shawn Smith
July 21st, 2009 at 7:47 am
Shawn Smith,
Do a search for that on google. I fixed my gateway 7510gx with the same problem with just a hot melt glue gun. worked like a charm. There is a tutorial on the web on how to do it.
Matt
July 21st, 2009 at 6:02 pm
Hello
I have a PCG-K33 vaio that i need to repair, the problem is that when i turn on the laptop i can see the logo of vaio and even if I enter to the bios setup I can see everything as normal, but in the momemnt that windows starts the back light goes off. I tried to reinstall windows but same issue goes off int he middle of the installation. And the video card is working because if i connect the laptop to a monitor I can see everything and If i get closer to the screen i can see the images but really realy dark.
What can i do? do you think that is the Inverter or the Lamp Light?
Thanks for your help
July 22nd, 2009 at 6:11 am
My son dropped his Gateway notebook. The LCD cracked. I removed it and order a replacement screen (actually 2). I installed both, but neither screen worked. I connected to an external monitor and everything worked.
Could I have received two bad replacement screens? or should I assume the inverter or backlight need to be replaced??
Thanks for any and all advice.
John
July 25th, 2009 at 10:18 am
I have a Dell Inspiron 1720 with Vista. If I just turn it on, I get a message to press any key to boot from floppy. It will only boot upcorrectly when I press the F8 key as soon as the DELL logo appears. When I ran diagnostics it gave error code 0322 and said the error was in accessing the LCD inverter. As long as I boot from the F8 key my LCD screen is fine, sharp and clear. It does not fit the description of a bad lcd inverter. Does anyone have any suggestions?
July 25th, 2009 at 3:30 pm
This is great info. I’m a PC tech who does a lot of work for a lot of clients (sometimes I think too many).
I often left the LCD repair up to guess-work (whether it was the inverter or the LCD itself). For the most part I guessed (or deduced it correctly), but those ones I guessed wrong on were costly and time consuming mistakes I know I could have avoided.
I used to work with a group of technicians who would hoard their knowledge and never share what they knew with other techs. Needless to say nothing got done very well in that shop, I’ve since struck out on my own and have been doing very well.
Your little blog was very well written, informative and extremely helpful. I thank you for sharing your knowledge.
July 28th, 2009 at 3:09 am
Dell model no:pp01s lobtop power on and off when tested power 18.5v shows be in components all matherboard.doide 330j12 has no power.
July 28th, 2009 at 7:27 am
Hi,
Nice site to stumble upon.
I have a Laptop here with a strange problem.
its a Toshiba Equium m50-164 and the screen brightness seems to be backwards.
the Fn key for brightness works backwards so up is for lower and down is for higher.
now the problem that creates is that the screen brightness will not go up full (as the button is meant for darker and wont darken enough to fully turn off the inverter)
any ideas??
July 30th, 2009 at 7:02 am
i have a Fujitsu Siemens laptop, water poured on it i was able to dry it up and have it working but the voltage to the LCD inverter is 1.7 which i know should not be so, this has made my back light not to work, i will like to know what the possible back light voltages are so if i can tap from a point in the laptop to have it work. i am running a 14.4v batt.
July 30th, 2009 at 10:20 am
Hey, thanks for the GREAT info. Please dont ever get rid of this site.
August 4th, 2009 at 3:58 pm
Hi, found this site a number of months ago and regularly use it as a reference point, keep up the good work. I would be interested to know how i can test if the inverter is getting the required voltage from the motherboard? I am sure this must be possible but i am inexperienced in testing electronic components.
August 8th, 2009 at 1:55 pm
PaulQ,
You can test the incoming voltage with a multimeter. When you take a look at the inverter side oriented to the cable (not LCD backlight), you’ll see a few a few connectors.
One of them could be marked pin 1. You’ll have to measure voltage between pin 1 and ground. It could be somewhere between 10-20VDC.
Be very careful, do not short the inverter with the voltmeter.
August 11th, 2009 at 5:02 pm
cj2600
thanks for responding to my query it looks like i misread the article above as your advice seems to be the same as was mentioned. Apologies!! I would also be interested to know how to trouble shoot problems with the incoming power i.e. i have seen laptops with faulty dc jacks which i have resoldered and still did not work is it possible to test the board at a given point and determine where the fault may lie or would you need a board schema?? Perhaps this could be a subject for a future article??
Regards
Paul
August 11th, 2009 at 5:54 pm
I want to know if a bad inverter or floresent tube can give low
brightness (about 20% to 25%) I can adjust the brightness with
color settings and get it passable but the laptop (QOSMIO F25)
should be quite bright!
I have orderd a new inverter but I just wanted to pick you brain.
August 20th, 2009 at 2:51 pm
Fantastic instructions – very clearly written with nice photos. It’s been really helpful to me. Keep up the good work.
August 22nd, 2009 at 11:43 pm
Great test, saves lot of trouble and time and takes the guess work out of it.
August 25th, 2009 at 8:16 pm
dear,
mauricio’m writing here from Brazil, I think its very good this site for people who are having problems in their notebooks, congratulations and grateful, I have a similar problem with a dell, sometimes the backlight turns on the sometimes not, sometimes which binds and because the place connected to external VGA external monitor, but when I disconnect the external monitor it’ll turn brown,
I hope your answer.
Thank you for teaching my teacher.
August 26th, 2009 at 11:41 am
Great reading I’ll tell you,,here’s my story on a Dell 1501 the lcd screen won’t apprear until a couple of hand slaps on the left rear of the screen and will then only stay on with slight pressure supplied by my hand on the left bottom corner pulling towards me. This works in any postion of the screen and once the pressure is release it slowly fades to white and other colors. What is on the left side that would do this,,a bad ground or connector. I going fix this some way,,,Please help me.
August 26th, 2009 at 9:25 pm
AL POE,
I’m discassing LCD failures in this post. I think your failure is similar to the example 7.
I would say you have a faulty LCD screen and it has to be replaced. Apparently there is a bad solder joint somewhere on the LCD controller board and when you apply some pressure on the screen you temporarily fix it.
August 26th, 2009 at 9:31 pm
mauricio,
Can you see a very very dim image on the screen when the backlight is off? It’s possible you have a faulty inverter board.
I do not understand this part of the description. The external monitor turns brown?
September 1st, 2009 at 4:24 pm
Hi!, i got a problem like that
I have an Acer X193w and it turn normally but in 2 seconds the light turn Off and i can see the image, its kindda screensaver..
can you help me?
PS: sorry about the bad english bro
Thanks!
September 2nd, 2009 at 12:39 pm
I have replaced the lcd and the inverter on a gateway mx8738. I am going to try the multimeter test later this evening to see if the inverter is getting power. My screen now will only show a faint image. I dont have a lid closed switch, but was wondering if this computer has a magnetic switch and if so how would I test it or find it? I have also changed the lcd cable out but still nothing. When I boot the computer without an inverter connected at all it does the same thing as if it was connected and bad, dim screen. Any other things I should check before parting out this laptop?
September 7th, 2009 at 3:22 am
Hi, I have a problem with a laptop, Dell D830 when I turn it on, the screen brightness is ajustable with “Fn key” at night is OK but at day the brightnes is to low. How i fix it???
September 17th, 2009 at 5:45 pm
I have a similar problem with my Desktop LCD, a LCD Flatron W2242T.
The bottom half of my screen is dark and has light spots right at the bottom, whereas the top half works perfectly. I was considering buying a new screen which wud set me back $300 = =”
but this site has given me hope, maybe i have a faulty backlight at the bottom. Any advice on what i should do?
thanks guys
September 18th, 2009 at 10:07 am
Could the bulb and the inverter board go bad at the same time?
I sent the new inverter board back and ordered a new LCD screen. When I put the new screen in it’s still dark! I’m guessing they were both bad and now I’ve got to reorder the inverter board…
Thanks for your help!
September 20th, 2009 at 4:58 am
Hi everyone,really need help with my compaq MA8.
when turned on,nothing appears on the screen and the touchpad lights up only for a few seconds and then goes back off.After that,nothing happens and any key combination given does not even give the usual beeps after.
I would appreciate any suggestions,thanks
September 20th, 2009 at 7:49 pm
waligi,
1. I would test the power adapter. Maybe the adapter is dead and the battery doesn’t have enough power to start the laptop.
2. Check memory modules, make sure they are properly connected to the motherboard. Try reconnecting memory. Try removing modules one by one and test the laptop with one module at a time. It’s possible that your problem is related to memory.
September 20th, 2009 at 8:08 pm
Jesse,
It’s possible but not very likely.
1. There is a chance that one of the new parts is defective.
2. You didn’t connect them properly. Try reconnecting parts.
3. If you replaced both but still experiencing the same problem, it could be related to the motherboard. I cannot tell what is wrong without looking at the laptop.
September 20th, 2009 at 9:55 pm
Stefan,
I believe desktop LCDs have two backlight lamps inside ( I could be wrong).
Apparently one of the backlight lamps in your monitor is bad and has to be replaced. Cannot help you with that. I work only with laptops.
September 23rd, 2009 at 10:47 am
I have a Dell Inspiron E1705 with an WXUGA+ display. I accidently closed the laptop screen cover when a pen was still sitting on the keyboard. Since then, about 1/3 of the screen (on the left side) is dimmed. It never gets really dark, but it’s definitely dimmer (and harder to see) than the rest of the screen, which looks normal. The transition in brightness is gradual – there’s not a clear “line” separating dim from normal. The image is otherwise fine – just dim in that left section of the screen. Is it a inventor problem? or backlight problem? or do I need to get a new lcd screen to fix it? Help~~~
September 23rd, 2009 at 6:16 pm
hannahtuk,
It’s very common.
I don’t think that your problem is related to the inverter board because the rest of the screen is still bright. Apparently, you’ve damaged the backlight lamp inside the screen.
That means you’ll have to replace the screen.
September 23rd, 2009 at 9:14 pm
:’( That is too bad… It is the most expensive part! :’(
Thank you very much for your reply. I now for sure know what to buy then. Thank you!!~
September 26th, 2009 at 3:04 pm
.
does inverter or the backlight problem cause your screen to be black permanently if not replaced?
I have a problem with my old laptop screen – sony grx series – that doesnt seem to turn on eventhough everything else seems to work fine. I can only get the screen to turn on only if i remove and reseat the ram or “shake” my laptop a couple of times.
is this indication of an inverter or backlight problem?
.
October 5th, 2009 at 4:37 am
hi
dear
i study y r above page really very intrested
i have laptop reparing center here in my city
i have often needs for laptop ics for motherboard
reparing will y help me for my requrment of ics
and chip motherboard according requerment
thanks again and again for such a information
best regards
October 7th, 2009 at 2:10 pm
I have an HP ze5478cl. the lcd works for a minute goes grey then rolls like an old tv set with vertical hold problems, then comes back. it works fine with an external monitor.
so , my question is…LCD? Inverter? backlight? which is bad?
Thanks, Ron
October 7th, 2009 at 7:27 pm
Hi,love this,it is so informative!
I’m having a similar problem,but not quite the same as what I’ve been reading & I hope you can help me.
I have a Dell Inspiron l6400 laptop. Nothing has happened to it, one day I turned it on & the bottom 1/3 of the screen has gone white/gray. There still seems to be light, but can’t see anything. When it 1st started,I could tap the bottom of the laptop it would come back on, but nothing brings it back now.
I took things apart to check for loose connection to lcd panel. Everything seems ok,no visible damage or anything. Checked the connection,unplugged & plugged the cable back in where it connects by the power button – nothing! Hooked it up to another monitor & dispaly on that monitor is fine.
Does that mean I need to replace the entire LCD, or could it be a bad cable or something else? I don’t want to spend a lot of $ to replace something & have it still not work!
I appreciate any advice/help you can give me.
October 9th, 2009 at 2:05 pm
Hi,
Great site! I have an IBM T30 and came home one day to the screen being dark. It lights up during reboot, logs on to windows and goes black again. I don’t see any faint image, but maybe I need to look harder with a flashlight. The unit has a docking station. I setup an external CRT on the docking station and it works fine. Device manager says everything is fine. The properties tab for display shows two screens inclduing the CRT and LCD. It says the LCD is “not active” if I recall right. I’m wondering if this is a problem with the inverter? The docking station probably has a card in it that is operating the CRT? Also, before ordering an inverter, I can’t determine which one it is. There are two different part numbers out there for my model and I don’t really want to take the laptop apart twice, once to find the number and one to install the part when I get my hands on one. I went to numerous sites, but they just identify with the T30 verus the full model which is a T30 236697U. The two part numbers I am finding out there are: 26P8412 (150nit LCD) and 26P8411 (200nit LCD. What are the nits? I have gone to the Lenovo / IBM site. It only lists an inverter / screen combo pack number for certain models and does not even list this model number. Thanks.
October 13th, 2009 at 11:02 pm
Tony,
Instead of rebooting the laptop, try tapping on the lid close switch – a small button by the hinge. Can you light up the screen when tapping on the switch?
On some IBM laptop it’s really hard to see anything on the screen when the backlight is off, so look very closely.
Your descriptions sounds like a problem with the inverter or backlight lamp. Try replacing the inverter board first, they are not expensive.
I would find the FRU part number on the existing inverter and use it for buying a new one. It’s not difficult to removed the bezel, takes only 5 minutes. You don’t have to disassemble the entire display, simply lift up the lower part of the bezel, find the inverter part number and put it back together.
October 16th, 2009 at 4:37 pm
Great site!
I have an HP ze5478cl. the lcd works for a minute goes grey then rolls like an old tv set with vertical hold problems, then comes back. it works fine with an external monitor.
so , my question is…LCD? Inverter? backlight? which is bad?
Thanks, Ron
October 18th, 2009 at 5:15 am
Great site!
I have a related problem with my 5 year old dell latitude d810. The screen is now dark and the image on the screen is barely visible but still working. Everything else works fine. Shortly before this problem, the screen started to flash when I opened windows or was slightly pink. Your site (and others) seems to indicate that this may be the inverter or the back light of the lcd. I have looked at your other post on the backlight, but does the way the problem occurred tell me something informative about its cause?
October 25th, 2009 at 10:17 pm
antoine,
Most likely the pinkish screen is related to the backlight lamp failure, not the inverter failure.
November 5th, 2009 at 2:46 am
Just to say abig thank you for putting this up, I thought it was excellent and it has helped me in resolving the issue of the backlight I have with my Toshiba Equium Laptop.
Props to you.
Dave
November 5th, 2009 at 4:17 am
Hi i am facing a problem i installed new invertor in my dell laptop decause of old one is not working but my display keys function i,e Fn + Arrow keys not working i also fomate my hard disk with new partition installed Windows Xp.
Pease help me how i can enable Fn keys funtions.
Quick response highly be appreciated.
Thanks
November 5th, 2009 at 11:34 am
faysal,
I’m not sure why the Fn key doesn’t work. Did you reinstall all factory drivers and software after installing XP? You can install it from the CD or download from Dell website.
November 5th, 2009 at 12:04 pm
Boss,
from where i can get the company service manuals and repairing guide with flow chart for laptops of all brands, pls help me
November 5th, 2009 at 8:17 pm
Thanks,
No im not installing factory drivers i have to find out then istall all
i want to ask that this keys are not working because of new invertor ? or some driver problem ok first i intalled drivers then lets see it is enable or not.
Thanks a lot again
Faysal
November 6th, 2009 at 10:32 am
faysal,
I don’t think so. If the screen lights up the inverter is working properly.
I guess you are missing a piece of software controlling the Fn key.
November 13th, 2009 at 3:02 am
Hello. My notebook Samsung R50 has its some left portion of it more darker than the rest of the LCD screen. And overall I have also noticed that my 3 year old this notebook of mine had its overall brightness reduced.
My question is: is it the CCFL needs to be replaced or is it the inverter gone bad?
November 13th, 2009 at 3:00 pm
I was given a laptop to check out since the monitor was not working. A month ago I concluded the monitor was just shot and needed to be replaced as I was able to get video to an external monitor but got no image on the LCD at all.
TodayI decided to break it out again to use with an external monitor. But this time I noticed if I pulled the monitor from the top forward (i.e. I pull it as I might close the laptop, But only pull enough until I lose the “slack”) I was able to see the monitor display without the back light. Once I let go, the image disappears. Then if it’s played around with in some other random fashion, I can get the display and back light to work.
I am wrong to assume that I may just have a wire problem and not an inverter or backlight issue? I took the laptop apart, but I just couldn’t figure out how to get the monitor off so I could take the bevel off it.
Laptop is a Toshiba A205-S5871.
November 13th, 2009 at 4:06 pm
Tamal,
It’s hard to tell without testing the laptop with known good spare parts, but I think this is related to the CCFL.
From my experience, when inverter fails the entire screen goes dark.
The inverter either works and provides power to the backlight lamp, or doesn’t work and the backlight gets no power at all.
I think the backlight lamp goes bad.
November 13th, 2009 at 4:36 pm
Duane,
You’ll find my laptop disassembly instructions at http://www.irisvista.com
You can use instructions for a Satellite A215, it’s similar or at least very close to Satellite A205.
Could be bad connection between the video cable and motherboard. Try reconnecting the cable.
Also, could be defective video cable.
November 14th, 2009 at 10:13 am
Sweet! I went ahead and tried again and got to all the wires. Disconnected the wires and made sure the monitor cable was connected firmly, and now it finally works again.
Thank you~
November 20th, 2009 at 1:30 am
Be for this post i have no idea regarding how to open LCD screen and make repairing of LCD screen .You provide very nice information and fantastic things.I am really glad about this.