Any ideas on how to properly test voltage on the LCD inverter input and output?
My Satellite 5105-S701 fails to light the backlight. I can see the image when using a flashlight and the image on an external monitor is fine. I tested the output from the inverter board and am getting zero volts. The input has many fine wires and without a pinout I have no idea how to test for voltage going into the inverter. I took it to a laptop repair place and told them I thought it had a bad inverter and would they please diagnose it for me. I guess I was too specific because when I picked it up they simply told me the inverter was OK and handed it back to me with the backlight still not working and no idea why it’s not working.
Any ideas on how to properly test the inverter input and output? I would try a known good inverter but I don’t have one. Any other suggestions as to why the backlight won’t light? Or any other tests I can run? I’ve found all the software backlight controls and they’re all cranked up. Thanks for any help!
That’s a question I keep asking myself over and over. How can I test an FL inverter board using just a multimeter? Unfortunately, I do not have any straight answer at this time. I believe that you can measure the voltage on the input if you connect the positive probe to the pin 1 on the FL inverter and the negative probe to the laptop chassis. The multimeter should be set to test DC voltage. I think that the voltage on the input could be somewhere between 9-30VDC, just in case set the multimeter to a higher voltage. The pin 1 on the FL inverter board should be marked; I’ve seen it marked before. You should get some voltage on the inverter input. If you get zero volts on the input, then it’s possible that cable is bad or the connection on the system board is bad. Now about the output voltage. I believe that you can get an accurate readings on the FL inverter board output only if it’s loaded properly, in other words if the backlight bulb is connected and it’s in a good working condition. It could be a very high AC voltage. I would set the multimeter to at least 1000VAC. Be careful, it’s a very high voltage and if you do something wrong and short a circuit, you can permanently damage the laptop. Sorry, but I cannot provide more specific information. If you find any info on how to test a failed backlight with a multimeter, please let me know.
Usually, when I have a problem with the backlight, I unplug the screen and connect my test backlight bulb. If it lights up fine, then the backlight in the LCD screen is defective. If it doesn’t light either, then most likely it’s the FL inverter board fault. Video cables do not fail very often.
August 2nd, 2006 at 1:27 pm
Just wondering where I could purchase a bulb to be used for testing FL inverters. Is it just easier to grab one out of an old dead laptop (will I run into power issues, or do they generally run around the same voltages?)?
As someone who just bought a FL inverter because I was sure that’s what it was, and now can’t return it, because it was actually the lamp, I’d really appreciate any help, or a point in the right direction…. Thanks
October 21st, 2006 at 10:43 am
Hi, I have a sony vaio pcg-v505ex and I’ve cleaned the lcd screen really well, but I notice fibers or dust under the lcd screen and although it doesn’t effect the performance, its something that wears on me and gets really annoying, just wondering if there is a way to get under a lcd screen and clean the underside of it. thanks
November 4th, 2006 at 2:18 pm
Monitor problem.
I have a Toshiba Tecra that has run perfectly for a year. It has XP professional on it.
I used it yesterday for 6 hours without a problem.
At the end of the day I noted that some areas of the image looked fractal, flickered and developed a pinkage cast.
I used the laptop to drive another monitor. I could see the problem there.
I let the computer for cool for an hour.
On restarting it the image was perfect but within about 10 minutes I could see the problem developing on it again. When I move the cursor it seems to trigger the problem in parts of the image.
When I reboot the machine and the Toshiba image appears I see thin black vertical stripes through the Toshiba letters.
I asume that this must be a heat sensitive failure in the video card. So this needs to be swapped out?
This means swapping out the motherboard, right?
I have never had this done. Can this be simply done in a way that does not require reloading the programs?
I hope so.
Help with some comments greatly appreciated.
November 5th, 2006 at 12:49 pm
Peter,
If you can see the same pinkish cast on both screens – internal laptop LCD and external monitor, then the problem is not related to the laptop LCD screen or video cable. Usually this issue is related to a faulty video card or in some cases bad memory. Just in case download Memtest86+ utility and test the laptop RAM. If it fails the test, replace the memory. I have another post dedicated to a bad video output (www.laptoprepair101.com).
It also could be related to a faulty video card or RAM. Most likely it’s related to the video card.
It depends. Some Tecra laptops have removable video cards, the card not integrated into the system board. In this case you can replace just the video card and leave the system board.
On some models the video card is integrated into the motherboard and if it goes bad you have to replace the entire motherboard.
I don’t know your laptop model and cannot say if the video card is integrated into the motherboard.
Replacing the video card or motherboard is not a simple process. The laptop must be taken apart in order to replace these parts. I have created a few guides for taking apart Toshiba laptops (www.irisvista.com). Take a look at these guides and you’ll get an idea if it’s too complicated for you.
After you replace the motherboard or the video card it is not necessary to reload programs.
November 6th, 2006 at 8:02 am
I have a problem wih my laptop’s screen. When I turn it on, it works just fine for like 2 minutes and then it goes dim. Its not a brightness issue, I’ve tried the brigthness adjustment thing and it does not solve anything. The picture is still there, just very very opaque. I plugged a moniotr to my laptop and it works perfectl, so its not any video card problem, it must be something with my monitor. Any ideas of what I can do?
(Specs: Dell Inspiron 8600, Pentium M 1.6 GHz, 512 MB Ram, 64 MB Nvidia Video Card)
November 6th, 2006 at 10:54 pm
Miguel,
It looks like the FL inverter board (located inside the display assembly) is failing. Most likely you can fix the laptop if you replace the inverter. Here are instructions for Dell Inspiron 8600 laptop, click the display assembly link. You can find a replacement display inverter board online for about $30.
November 21st, 2006 at 1:21 pm
Hi,
I have a Dell Inspiton 8600. I just got back from a 5 hour drive(laptop was in the car although in a targus laptop bag) and noticed that the LCD display was dim on the top right. To debug, I tried to display a black background and noticed a lot of white light leaking in from the top right which makes the display dim on the right. I connected an external monitor to the laptop and that works fine. Rebooting the laptop doesnt help. I did check the motherboard end of the display cable and it is fastened well. Any idea what could be the source of the problem? Do I need a new LCD or is it a faulty inverter/cable? Any help would be appreciated. Thanks.
November 21st, 2006 at 10:10 pm
Sairam,
It’s definitely not a faulty inverter. The inverter board works like a power supply for the backlight bulb and if the inverter goes bad the backlight stops working at all.
I think the LCD screen has been damaged during the travel. Is it possible that you had something heavy on the top of the notebook bag?
November 21st, 2006 at 10:19 pm
Hi,
Nope, there was nothing heavy on the bag. It was in the trunk.. it is possible i guess that it got damaged during transit but it is kind of surprising. So replacing the LCD is pretty much the only option?
-Sairam
November 22nd, 2006 at 12:49 am
Sairam,
I cannot think of something else.
Yep, sounds like the LCD is only the option.
November 23rd, 2006 at 6:46 am
Hi
I got a Toshiba equium m40×203.recently my screen showing red lines all over the lcd as i move the mouse pointer along.i tried connecting it to an external monitor n have the same problem.flashed the bios(from some help forum) but the problem still remains.do you think wil hav to replace the video card?and if posible how.
many thnks
November 26th, 2006 at 8:43 pm
Hello. I have a Toshiba P35-S611 (bought a little over a year ago and warranty done). I am having similar LCD problems like a few others where the screen has gone dim. It started one day when for some reason it went dim and I noticed a high pitched noise coming from it. I turned off the laptop immediately. I waited a while then turned it on and it looked fine, but then went dim again the noise came back. Now I can’t even turn it on, just starts dim with sound. I am pretty sure it is a similar screen issue and the noise has something to do with the screen.
I’ve published this comment as a post. You can see the rest of the comment and a possible solution here: LCD screen went dim and I noticed a high pitched noise coming from it.
November 30th, 2006 at 6:52 am
Hi
I’ve got an issue with my advent 7041 laptop. The screen doesn’t seem to work, but computer works fine with external monitor. The laptop repair shop said it could be any one of three main problem: lcd, inverter, video/graphics card. He said that an lcd would cost £350 + labor. I for one don’t think its the lcd, on the basis that its in almost perfect condition (still has (had!) screen cover). I also don’t think it’s video card since it works fine with monitor. That leaves the inverter. However, i’m pretty sure the backlight is working as you can turn it on/off and notice the difference in the dark. I’ve opened it up and pushed all the connectors about, but still prblem persists. Any ideas?
November 30th, 2006 at 10:37 pm
Ambia,
Do you mean the screen changes from completely dark to “life” dark? You can see the difference but the screen is still black, correct? If yes, then the backlight is NOT working. With a working backlight the screen would be bright.
Turn on the laptop and look at the screen. Can you see any image on the screen? If you can see a very faint image, then most likely you have a failed FL inverter board. In this case I would try replacing the inverter board first. It shouldn’t be very expensive to find a new inverter and you have a very good chance to fix the problem.
You can find more tips in my other post: How to troubleshoot and fix laptop video problems.
December 1st, 2006 at 1:28 am
Thanks, and perhaps your right about the backlight. Whether in the dark or not, if you swith the backlight on and off you can see the screen get a little brighter especially around the edges, and this is more noticable in the dark. As for seeing any image, then no. However, if you turn on the backlight, in the dark, you can see a faint thick line approximately a couple of centimeters from the bottom of the screen; but that’s about all you can see.
I’ve been searching heavily on the net to find an inverter for this model but with no luck. I’ve also emailed a couple of site to let me know when they do get some in. I’m begining to think that it’s the lcd, in which case it’s either 350 + labor or a new laptop; niether of the two is very appealing.
December 1st, 2006 at 8:17 pm
Ambia,
If you cannot see a faint image on the screen then it’s not the inverter board failure. Here I’m almost positive.
So, what’s left? The screen itself, the video cable and the motherboard/video card (I don’t know if the graphics card is integrated into the system board in your laptop). Take a look at the generic laptop display diagram.
For some reason I think that the problem is not related to the LCD screen. I would understand if the data channel fails (no image on the screen) but the backlight works fine or vice versa, the data channel works fine (you can see an image) but the backlight fails. Yes, in this case I might suspect the LCD screen. But why both channels failed at the same time? No data and no backlight? So the problem occurs before the signal goes to the video cable?
I think that you might have an issue with the motherboard/video card. Even though the external video works fine, you still might have an issue with the video card. That’s my guess.
It’s really hard to troubleshoot a laptop without actually having the laptop.
May be you should consider taking the laptop to a repair shop at least for diagnostics? They can unplug your LCD screen and plug a test screen and tell you for sure with module is failing. If the test LCD lights up with image then you have a bad screen, if the test LCD is still “dead”, then most likely it’s the motherboard issue or you have a bad video cable.
December 5th, 2006 at 1:30 am
Thanks. I also don’t think its the lcd or backlight. firstly, in the dark switching backlight on and off is very noticable so much so that i can actually see most of my keyboard with backlight. second, the lcd is in very good condition: never had any bumps, falls, scratches and so on.
The thing about taking it to a repair shop, is that i did. he gave an estimate of what the problem may be (lcd, inverter, video board etc), but unless i gave him £60 he couldn’t be sure. I’m just worried that i give him the £60 and then he says its the lcd which will cost 400 + to fix. Is there any way of testing the video cable, or know of where i can get some parts?
December 6th, 2006 at 2:57 pm
Hi, and great website. I was not really sure where to post this, so i figured here was best. Got a toshiba sat(A15-129) with a broken lcd. I bought a used lcd on ebay from a compaq, i had found a cross reference guide that said they were the same panel, and of corse it isnt! My questions: The main data cable connector on the toshiba is larger than the compaq lcd’s data connector, is there an adapter, or some way to splice the 2 together? Also, are FL inverters pretty much the same? can i use the toshiba inverter with the compaq lcd? thanks for your help, brad
December 10th, 2006 at 10:45 am
I recently purchased Dell d600 laptop on ebay. SXGA display screen had several scuffs, spots, dots, etc. Seller sent another display screen with no instructions and I cant figure out how to change display screens. Can you help with instructions or direct me to helpful website? Hope you had good vacation. Thanks.
Adam
December 11th, 2006 at 7:24 am
I have some issues with my Thinkpad A30P (UXGA NEC display). The Laptop once fell down splattering the backlight CC and the inverter, I replaced both and had no problems for about 2 months. Then the backlight startet acting strange, only working when the inverter got “full juice” from the mainboard, meaning when it was setting to highest brightness and connected to a power outlet. Soon afterwards, while operating with a replacement inverter to see if the problem went away I heard a fizzle and saw my screen go dark just to witness some smoke coming from the inverter.
Now – using a third inverter – I can´t get the backlight to work at all although it works using an inverter from a case CC. Additionally, the Power/charge LEDs on the inverter board don´t light up anymore. The display is working fine without any distorted pixels (though dark now) and I couldn´t find any faulty fuse on the mainboard or on the LCD board.
Any idea why the inverter seems to get no power at all? Can I get a pinout for an IBM inverter so I could fetch the needed voltage from somewhere else on the mainboard?
December 16th, 2006 at 12:34 pm
i have a t30 thinkpad with a strange video problem. i can’t find any information on it anywhere. The problem is with the internal LCD, the laptop will boot fine with an external monitor but if i try to switch to the LCD, the laptop shuts down. i’ve tried a replacement LCD from Ebay, but i still get the same issue. will not boot from internal monitor, shuts down, will not switch to internal monitor, shuts down. any ideas?
December 16th, 2006 at 7:02 pm
I have a dell 9100
There is no light on the lcd
If I look close enought I can see it booting up and get to the desktop
If I hook up a vga cable it will show me the windows logo and I can use it on the desktop with no problem
I Cant see the bios screen using the monitor so I cant change anything in the bios
What do you think I need to change?
the inverter
Video card
LCD
LCD backlight (I heard this is hard to do but I can solder pretty good)
December 16th, 2006 at 7:11 pm
btw when I first press the power button the light flashes
December 17th, 2006 at 12:21 pm
Matt Power,
Never seen problem like this before. First of all reflash/upgrade the BIOS. I guess it’s possible that the BIOS got corrupted somehow.
If I understand right, the laptop shuts down when there is a signal going from the motherboard to the LCD screen and I would assume you might have a faulty video cable (may be there is a short inside the harness). Or it might be a faulty motherboard but you cannot tell witch one until you replace at least the video cable. You already replaced the LCD screen and still having the same issue, so it’s not a screen problem.
Here’s what you can try. Unplug the external monitor and unplug the video cable from the motherboard. Start the laptop. You will not get any video, but at least you can see if the laptop boots or it shuts down. If the laptop shuts down even without the video cable plugged in, then I would think that you might have a faulty motherboard.
If the laptop boots up without video cable plugged it, do next. Plug the cable back into the motherboard, and unplug the cable from the LCD screen. Start the laptop again. If it shuts down with the cable connected to the motherboard then I assume you might have a faulty video cable.
Sorry man, I cannot tell you exactly what is wrong. It’s really hard to troubleshoot the laptop over the internet, moreover when the laptop has such an unusual problem.
December 17th, 2006 at 12:30 pm
Martin,
Here’s a summary I made from you comments 22 and 23:
1. the laptop LCD screen has no backlight but you can see a faint image on it
2. the laptop works fine with an external monitor connected. You have no problems working with the external video.
3. the backlight flashes on startup and then turns off
If that’s correct then most likely you have a faulty FL inverter board. I would go with replacing inverter first. LCD inverters are pretty cheap and you have a very good chance to fix the laptop.
December 17th, 2006 at 8:33 pm
Thank You Laptop Freak
I just ordered an inverter from ebay and will try it out this week when it gets here
December 18th, 2006 at 1:31 pm
in reference to my question(#18), ive done a little more research and i think i can splice the cables together, but i cannot find the data sheets for the lcd’s i have, although all i really need is the pinouts. would you have, and or can get these? Also, i still wasnt sure on the inverter deal, i think it will power the other bulb, but i can maybe swap bulbs as well. heres the lcd panels i have:
LG Phillips=LP150X06 =30 pin connector (what came in the toshiba A15-129 i have
Samsung=LT150X3-126 =20 pin connector (what im trying to put in the toshiba)
thanks, brad
December 19th, 2006 at 8:32 pm
Sorry Brad,
I don’t have the pinouts and have no idea where to find them. By the way, I didn’t find any Toshiba laptop where Samsung LT150X3-126 was used.
December 26th, 2006 at 1:06 pm
Hi,
My laptop is HP Pavilion ZE4610US. I am planning to buy a new desktop PC. I was wondering if it is possible to use my laptop’s LCD for my new desktop PC.
Thanks…
December 28th, 2006 at 11:31 am
Any advice for removing pressure marks from an LCD screen – not afraid to dismantle screen but would like to know if there is anything I can do ?
My laptop is a Lenovo T20. Possibly caused by the screen being pressed against something when closing the lid or from the top of the laptop having something pressed against it whilst closed.
December 28th, 2006 at 8:26 pm
Michael,
You can set the laptop to output video on an external screen, but I don’t think it’s possible to use the laptop LCD screen for a desktop PC.
December 31st, 2006 at 12:40 am
my toshiba qosimo started showing coloured horizontal lines all of a sudden at first it was one,then two there are 5 lines,seems like the lines are increasing,when connected to an external monitor it does not shot the lines,what can be wrong
January 1st, 2007 at 8:09 pm
Lawrence,
If the lines appears only on the laptop LCD screen but not on the external monitor, than I would guess that you have a faulty video cable (less likely) or bad LCD screen (more likely). You can find more help regarding this topic here.
January 4th, 2007 at 10:54 am
Thanks you for your advice
I recently bought an inverter for my inspiron 9100 and it fixed the problem
1. The part does not bolt onto my Inspiron 9100 it has to holes for the screws but they don’t line up on my display they are too far apart. Is this the correct part?
I put 1 screw on it to hold it in place for now
2. When plugged in it works fine but it gets real hot probably the same temperature as a fully charged battery while its charging
Is it suppose to heat up and stay that hot?
Will it eventually burn out if it is getting that hot? I don’t want my laptop to catch fire
January 4th, 2007 at 8:07 pm
Martin,
I think it’s possible that you purchased a wrong FL inverter for your screen. Usually it gets warm but it shouldn’t be hot. Also, you should be able to mount this inverter board the same way as the old one was mounted. At least you know that the problem is fixed and fortunately Dell inverters are not expensive.
January 5th, 2007 at 12:41 pm
Matt 21:
I have the same problem with a thinkpad a22e(works good with crt, will shutdown when using lcd). I removed the lcd panel and cable and it still acts the same. Thinking it is a bad motherboard even though it works fine when the CRT only is used. Did you find anything else out about this problem?
January 5th, 2007 at 5:53 pm
Thank you for the advice
This is the only one I can find on ebay
I bought 2 different inverters on ebay for the 9100
1. did not bolt on and wanted to catch on fire when I tried it
the second is this one
The seller told me he has sold it to other people with a 9100 and it just doesnt bolt on right
I lowereed the brightness and it doesnt get hot anymore
Ill look for another inverter hopefully this one doesnt catch on fire or anything
January 8th, 2007 at 10:05 am
Hello, my Toshiba Satellite 1905 was dropped and hit the coffee table and upon looking at it you can see the images, (ie icons) but it had a crack running down the screen which appeared distorted, so I thought its got to be the LCD screen. So I ordered a used one of ebay. But in the mean time I took it to a local computer repair company who looked it over and told me they could not repair it. Weird I know… So I recieved my USED LCD from ebay, pick up my computer from the repair man and attempted to repair my LCD myself. I take it home open it up and come to find out that he replace my Toshiba screen with a Sharp. So then I remove the Sharp screen and install the Toshiba screen hoping that would make it work, instead all I get is a black screen nothing on it. The computer boots up fine but no images on the screen.. So my next thought was its goto be the FL inverter.. What should I look at with respect to that?? Is it possible this man removed my Toshiba inverter and replaced it with a Sharp just like he did the LCD screen… or is there something I should try.. My only thought is when my laptop left me it was illuminated, just a crack running thru screen and now I cant even get it to light up. thank you in advance for help
January 8th, 2007 at 3:22 pm
hi, i’m having a similar problem and think it might me an inverter issue, could the inverter cause the laptop to not power up also…. when it does power up, the screen is really dim and i can barely make out the hp logo. just trying to rule every thing out. already replaced the motherboard and ac adapter. still nothing. thanks for your help.
January 9th, 2007 at 5:18 pm
Nina,
You dropped the laptop and after that you still can see the desktop (I assume it’s as bright as before) but there is a crack running down the screen, right? This tells me that there is nothing wrong with the FL inverter, it’s just a cracked LCD. You shouldn’t replace the inverter board.
So you’ve purchased a used LCD from eBay and when you connect it to the laptop it doesn’t work. There is no image and no light, right? Are you sure that the new LCD screen is compatible with your model? Try connecting the old, cracked LCD screen back to the laptop. Are you still getting the backlight? If not, can you see a very faint image on the screen if you look very closely?
January 9th, 2007 at 7:04 pm
Okie1211,
Not sure if the inverter can cause such problem, doubt it. Here’s what you can try. Disconnect the video cable from the motherboard and test the laptop just with an external monitor. If you still have intermittent startup problems, it has nothing to do with the inveterate board.
January 10th, 2007 at 7:27 am
Thank you for replying so soon. To answer your question. Yes the LCD screen was still as bright as before just with a crack in it (no other problems or defects was working great). And here is the part that is killing me. When it left me at the repair facility it still lit up. Its when I picked it up this past Friday, is when the screen was black upon booting up.. SO that is why in my mind once I REMOVED the SHARP screen that he (repair man)had put in and I replaced it with an orginal used Toshiba Screen and it still did not change from the black screen. That is when I thought he must have done something else to this unit, I mean if nothing else the sceeen should atleast light like before. So the only other thing I could think of is maybe he changed the inverter to make it fit the other screen or maybe WELL WHO KNOWS, all I know is it was a simple repair and (AFTER have my computer for a FULL month)all he could say was to me was, “oo hunny you should just buy a new one”… I have no way of proving he took or changed the inverter at least I dont think I do. All I know is that now my screen doesn’t even light, so I did order an NEW FL inverter for my model with the hopes it will fix the problem. I will be replacing it myself and was wondering if you could give me any tips on what I should look for or be doing when I replace it. thank you again for you help.
January 10th, 2007 at 10:53 am
Well i did remove the LCD inverter and sure enough i was able to attach an external monitor and get something. Now i just have to figure out what to do next. i get a HP logo screen with 4 different options none of which work. but thats for another day, at least i found out why the screen wouldn’t work.
January 10th, 2007 at 8:29 pm
Nina,
I’m pretty sure that before you took the laptop to a repair shop you had only a cracked screen. I’m not really sure what is going on now. I don’t think the repair man installed his inverter and left it in there, it’s not a cheap part that you just give away for free.
Try this. Even if you have a cracked screen with bad FL inverter, the laptop still should work fine with an external monitor. Connect an external monitor to the VGA port and start the laptop. Will it work fine with the external monitor? If the external monitor as black as the LCD, a new inverter board will not help you. There is something else wrong with the computer.
January 11th, 2007 at 2:43 am
that is what i’ve done, on the hp laptop the only thing connecting the mother board to the lcd is the inverter board. when this is left connected it will not work at all. when i disconnect it, it works.
January 11th, 2007 at 3:06 pm
okie1211,
So, the laptop boots fine with an external monitor when the inverter board is disconnected and will not boot when the inverter is connected. Sounds like a bad inverter?
Here’s one more thing to try, just to make sure that the problem is related to the inverter. Plug the video cable into the motherboard, plug the other end into the LCD and DON’T connect the inverter board. The laptop still boots fine without inverter connected? The laptop boots to the desktop without any problem (the image on the screen will be very dim)?
January 11th, 2007 at 7:42 pm
there is no way to plug the lcd into the mother board with out the inverter the inverter has to seperate types of connectors on each end. so you can not bypass it
January 15th, 2007 at 8:07 am
Hey Laptop Freak, Ok so I recieved the new inverter on Friday and installed it and the monitor lit up perfectly no lines – no degrades anywhere, it looks great, running perfect has been running all this weekend. And I put it to the ultimate test I let my 13 year old daughter surf the net with it.. (lol) but at any rate after looking at the inverter and compairing it to the other Sharp screen that local computer store put in who shall remain nameless but one that I will NEVER refer anyone to.. After looking it over HE DID in fact remove my orginal inverter and replace it with a dead one.. So I guess that is my lession to be learned get it in writting what they are going to be doing to your laptop.. I just knew that he changed something but I couldn’t prove it, because like I said when it went in there it lit just fine and when I picked it up (nothing) even with the new Toshiba screen replaced.. Well I just want to THANK YOU very much for ALL YOUR knowledge/help, it is truly apprciated..keep up the great work.
January 19th, 2007 at 10:05 am
In your article above you say “Usually, when I have a problem with the backlight, I unplug the screen and connect my test FL inverter bulb.”, what is a test FL inverter bulb and how can I aquire/make one?
-thanks
January 19th, 2007 at 10:24 am
Frank A. Madero,
That was a typo. Thank you, I fixed it.
I changed “FL inverter bulb” to “backlight bulb”. I have a few working backlight bulbs I pulled form broken screens and use them for test.
January 26th, 2007 at 6:29 pm
Easiest way: Hover O-Scope probe around the inverter t-formers. U should be able to detect the leaking high voltage current.
February 6th, 2007 at 2:07 pm
Hi there, ok sir to begin with thank you for your help, hopfully i can resolve this problem. I have a (Gateway laptop model# M305crv). recently i was replacing the internal male peice of the power adapter, anyways while I was taking the laptop apart, I wasent paying close enough attention I guess, So while taking the lcd screen off there were 2 wires “black and grey” which while in the prosess had come undone or removed, I can’t for the love of it figure out were those 2 lcd screen wires go when I putting everything back together. Any help or information would be greatly appriciated!!!!
February 6th, 2007 at 2:16 pm
Neil,
Most likely they are wireless card antennas. I guess the white wire goes to the main connector on the wireless card and gray one to the auxiliary connector. If you don’t have any internal wireless card installed, route the wires to the wireless card slot on the motherboard and fix them in that area to the motherboard with a sticky tape. Make sure contacts not touching the motherboard.
February 10th, 2007 at 9:28 pm
Hi. I’m kinda having the same problem with a presario 900. A kid broke the screen so, I found a used spare one at ebay. I’v replaced it on the laptop and when i start it light flashes for 1 second at the “COMPAQ” logo and then it goes dark. I can still see the image in the dark but no light. I’m thinking about a bad inverter. I placed back the broken screen and it doesn´t light either. I thought maybe the new screen has a problem but if the broken one doesn´t lights i guess is the inverter the real problem. So, I got my multimeter and tested the output voltage; it is 3 to 4 maybe 5 AC volts tops. I’m I right about the bad inverter looking at this voltages?
As far as I know, voltage should be “high” not under 10s right? and i don´t think that the screen has a super voltage multiplier inside that boosts the 4V to over 100…right?
First I thought maybe I got scammed with the screen but after seeing this output I guess the problem is my inverter.
Any help is welcome.
February 11th, 2007 at 10:03 pm
Luiguiv,
I think you might have a failed inverter board. I’ve published your question and some suggestions here. Hopefully somebody else can give you a better advice on testing the screen inverter.
February 15th, 2007 at 12:12 pm
I have a toshiba a45-s120 on which the screen cracked.
the original screen was model LQ150X1lHC3 B
the replacement screen i bought is model LP150X06
my only issue is that the plug to go into the inverter is different between the two
do i need to by a new inverter? can i just splice it? if i open up the screens will i be able to switch the wires?
if i have to get a new inverter how do i find out which model to get?
Thankyou
February 15th, 2007 at 10:58 pm
Boruch,
It’s difficult and very time consuming because wires are soldered to the backlight bulb. You’ll have to disassemble the screen, remove the backlight bulb, unsolder old wires and replace them. I wouldn’t go this route because you can easily damage the screen.
It’s possible but do you know witch one to buy? I don’t. I’ll have to have a bunch of different inverters to find out witch one will work with your screen.
I think you can try these:
1. You have two wires coming from the screen. Both wires have a small female connector on the end and they are secured inside the white connector. You can try releasing both wires from one connector and plug them into the other. It’s difficult but I think possible.
2. Cut off both connectors and solder the connector you need to the screen you need. It should work but you cannot return the screen back to the seller if you have to.
February 16th, 2007 at 7:50 am
thank you very much,
i followed option one but the pins to make the metal connectors stay inside the plastic piece were in different locations so it wouldn’t hold.
instead i cut off the connector with the wires from the old screen and spliced them and twisted them to the wires from the new screen and all is working well
once again thank you for your prompt response i wasn’t expecting a response for a while.
Boruch
April 8th, 2007 at 6:50 pm
There are horizontal stripes on my laptop lcd screen and I got them after I put a burned cd to listen to music. The stripes are pink on white background and green on black or other dark backgrounds. How do I get rid of it?
July 22nd, 2007 at 1:30 am
If you need to replace inverter, i wrote a walkthru. here:
http://www.hk3d.com/temp/InverterReplacement.pdf
July 31st, 2007 at 7:23 pm
Neil or Laptop Freak,
Do u have disassembly instructions for this laptop. I have a Gateway M305crv laptop. However, mine never gets a chance to boot-up. Everytime it trys to boot the OS I hear this clicking (one click) sound and then it turns off and restarts again automatically. I hear the fan going, so I don’t think it’s a heating problem.
September 20th, 2007 at 7:20 am
I assume other Toshibas with inverters may be similar however here are the voltages for a working Toshiba TE2100 Inverter by wire color with ground taken from the LCD Frame:
Blue: 4.58
Green: 4.58
Yellow: .1 (Brightness 1) to 3.2 (Brightness
Orange: .04 (GND?)
Red: .04 (GND?)
Brown 4.9 (5v Pwr ?)
Black 4.9 (5v Pwr ?)
At the mainboard end of the cable, these seven wires can be located on the left end of CN1 just under the left side of the keyboard cover as follows.
Green, Orange, empty, Black
Blue, Yellow, Red, Brown
The above voltages all fall to 0 when the lcd screen is turned off.
Input voltages can be measured with a pin tightly taped to the end of your vom. Fasten ground to your lcd screen mounting frame.
The inverter output can be measured for one glimpse of time with a 600 vac or higher multimeter.
(DANGER, TAKE HIGH VOLTAGE MEASUREMENT CAREFULLY AND AT YOUR OWN RISKS)
To measure the output, put the computer in hybernation state or power off, unscrew the inverter, flip it over to the component side and then gently pry away the plastic cover away from the input side (7 pin) of the inverter where it is glued. This will free the plastic cover to slide away somewhat from the inverter’s output high voltage side. Now startup the computer and first test to make sure an external monitor works. After determining that the computer’s screen should now be on, set your meter to 600vac or higher and locate the solder joints to the inverter’s output connector on the component side (back). Now watch your meter as you connect to the solder joints. You will see the meter quickly register some high voltage before automatically shutting down the inverter. You may have to hybernate or power down your computer down a couple of time to re-power your inverter and verify the inverter’s ac. The inverter shuts down quickly just after you touch the meter’s leads to the output.
October 13th, 2007 at 12:09 pm
This is a great site, and from what I’ve read, I’m guessing I also need to replace my inverter. I can see the image on my screen with a flashlight, but no backlight at all. I get no power reading at all on the output of the inverter with my meter. Image shows fine on an external monitor. It is a Toshiba Satellite A35-S159 laptop, but while looking for the inverter online, I notice several different ones listed for the A35 Series. Are there actually different inverters that work with my laptop? What would happen if I bought and connected the wrong one?
October 31st, 2007 at 4:19 pm
Hello
I’ve got a toshiba inspiron 8600 and it worked fine for three years and now the screen just went black no light or image at all,i tried contrast settings, i pointed a light against the screen, if i plug the screen into a crt it works but the tft is dead, i tried to read any voltage on the output of the inverter with a multimeter,and it was always 0,what it could be,i tried to read it in some resistance and i only got values bigger than 0 in 2resistence,have i got a bad inverter are this values because i’m using a multimeter, should i try a new screen could it be the black light,how do i test it???
October 31st, 2007 at 4:21 pm
Sorry i forgot to mention that the laptop startup to the windows all the time!!
December 26th, 2007 at 6:33 pm
Hi,
I have a compaq presario V2000 with monitor issues. I just replaced the inverter a about 2 weeks ago, and everything was running smoothly and then all the sudden, back to the very dim screen. Still sounds like an inverter issue. But I don’t think I bought a faulty inverter, as it did work for about 2 weeks. So is it possible there’s a short in the computer that is blowing the inverters? Any way I can find where that is without sending the whole thing into a shop and paying stupid amounts of money? I’m thinking maybe its possible the inverter just wasn’t connected all that securely and somehow came lose… But I didn’t drop the computer or anything, so I’m not sure how that could have happened… Any ideas you have would be greatly appreciated!
Thanks!
January 14th, 2008 at 8:17 am
I’ve been fooling around trying to work out an decent, non-invasive laptop inverter test that doesn’t require a spectrum analyser for years. Finally stumbled on the idea of using a decent multimeter with a KHz reading or a true RMS meter, and just using the probes as an antenna. Did an illustrated page on both:
http://www.fonerbooks.com/test.htm
The cheaper meter doesn’t work on higher frequency inverters.
Morris
March 3rd, 2008 at 9:10 am
I have Toshiba 2435 -S255 Laptop, from two weeks i have send it to a non certified service center to check the sound line-out problem, but they didn’t know how to fix it, anyway after two days from the service, when i started my laptop the backlight of LCD worked for like two seconds then turned off, i went back to them and they said to me it is FL – Inverter problem, so they replaced it, which fixes the problem, but after that i have this wired problem when i shutdown the laptop by removing AC adapter & Remove the battery (the non traditional way), the backlight stopped working, but when i shake the laptop a little & start the laptop the light works back again, So anyone have any idea why when i shake it, the light works? this is really confused me!!!!!!???? Adam
April 8th, 2008 at 6:20 am
Hi, I have a problem with my laptop display truning dim after I start the computer. I replaced already the lcd inverter cable and is still gives me the same problem. I tried to test the inverter input with a voltimeter and getting around 14 Voltage3 which it should be alright, then I tested the inverter output with one of those light bulbs used for light up the mod cases and it will light up but intermittenly. Is that how it should be or is a case of not enough power? Does that mean that the inverter is faulty? Any help would be greatly appreciated..
April 20th, 2008 at 10:23 am
Morris Rosenthal is the man! Thanks for that post.
Whipped out my Multimeter and checked a good laptop and I see the high frequency. Then went to my dark laptop (which I can see if I shine a flashlight on it) and No Frequency. My screen lights dimmly when cold booted and in a short time fades out.
I had previously inspected and flexed the inverter input cable while running didn’t change anything. I also replaced the inverter with one from ebay but it didn’t help (in fact it was worse). I suspect it was a bad part so re-installed the original.
After using your simple test, I think I’ll try to pick up another inverter.
April 26th, 2008 at 2:54 pm
I have a Toshiba a45-s150 with LCD problem. The lcd lights up bright but have no images. An external monitor works fine when hooked up. Could this be an inverter problem or a motherboard problem. The video card is intergrated.
Thanks
Mark
May 1st, 2008 at 11:56 am
Mark,
If the screen lights up, this is not an inverter problem. This first think to check would be the video cable. Try reseating the video cable on the back of the LCD screen. It’s possible the cable got loose. If reseating the video cable doesn’t help, I would probably try replacing the cable.
Could this be a motherboard problem? Yes, but I would play with the video cable first.
By the way, this could be a LCD problem too.
June 17th, 2008 at 8:32 pm
if you want a test backlight bulb, you can just get those CCFL light kit for case modding on ebay. they are cheap, like 5 dollars i think. you might need to reharness your connections to make them compatible however.
June 17th, 2008 at 9:22 pm
Thank you Derek,
That’s a good point and the only reliable method to find out what is causing the problem, the backlight lamp or the inverter.
July 7th, 2008 at 3:37 pm
I have an interesting problem.
The backlight on my laptop LCD lights up..but there is no image
Even when its Posting (before booting in the OS)
there is no image.
HOWEVER if i put pressure on a corner of the lcd, the image shows up.
Is it a bad Inverter or video cable or other?
July 7th, 2008 at 8:01 pm
Christian,
I think you have a problem with the LCD screen. I published your question and some suggestions here: Laptop LCD lights up but there is no image
October 31st, 2008 at 2:25 pm
I’m having backlight issues with a 17″ PowerBook G4. The light went out right after I replaced a bad video cable. OH, cruel irony!
March 31st, 2009 at 9:09 am
Hi,
I trapped one of the 7 wires running from my laptop motherboard to the inverter and it shorted out, my screen is on but with a dim image using AC power. I checked the inverter was working with an old CCFL. I got a bright picture back by touching Pin1 to Pin4 but on battery is was back to a dim picture (Accidently touching Pin1 to Pin3 made a spark and turned the screen off completely) Turning the notebook on I am now back to a dim picture, I took readings before and after the event -
Before (Dim Picture) Pin1 7.12v; Pin2 7.12v; Pin3 0v; Pin4 0v; Pin5 2.49v; Pin6 2.5v; Pin7 2.53v
Now (Very Dim Picture) Pin1 1.94v; Pin2 1.94v; Pin3 0v; Pin4 0v; Pin5 2.49v; Pin6 2.5v; Pin7 2.27v
Given that my screen and inverter are OK how can I get my bright picture back, using the keyboard dim keys only make it darker. There is no graphics card it must be built in and I get a perfect picture on an external monitor. Have I upset a setting on the motherboard by trapping the Pin1 wire and if so how can I reset it? Could I shock it back again? If so what pins and voltage would you suggest and how now that the voltage in Pin1 is so low it does nothing when I touch it to Pin4?
June 3rd, 2009 at 1:08 pm
Hey Everybody,
I had the same issue about measuring the inverter output, but I found out that if you measure in paralell to the inverter exit you will get no reading, I’m guessing the inverter can’t take much Amps, I tried measuring on a working laptop and when I tried to measure the voltage the whole screen whent dim, I had to shut it down and then turn it back on to have the screen light up ok.
On the bad laptop I just bought the backlight that I’m guessing is what’s wrong with it.
hope this helps anyone!
November 13th, 2009 at 4:47 pm
For testing inverter, check out this link…. it could save you a lot of time and hassle!!http://www.fonerbooks.com/test.htm
March 20th, 2010 at 9:31 am
So, heres whats up. I work at a mom ‘n’ pop style computer repair center, and i made an interesting discovery too. We have had a few Dell Inspiron 1525 inverter replacement issues. The 1525 model is prone to inverter failure, but what sucks more, is that when you put the new inverter in, you loose much control over the dim level. its not a compatability issue, it’s a domestic issue. Almost as if the new inverter is a replacement organ, and the body is rejecting it.
Now, this comes right back to “What’s the pinout?” and the answer to that is, YOU STILL HAVE TO SEARCH FURTHER!!
honestly, it seems as if the consumer is NOT allowed to know the inner workings of their own laptop screen. BUT, i bought a bunch of cheapy inverters, that are only 4-pin, AND come with a 6″ harness. So, with a 110ohm resister on the dim level pin, and +5VDC on the power and control pin, with the ground connected to the chasis, I’v been snaking the wires down through the hindges, and soldering them to the USB jack for my +5VDC power. granted, there is now a breif moment when the system turns on, and off, where the LCD turns off, but the inverter is still on, resulting in a blank white screen for aprox. 1/2 second.
There, theres your dim screen solution.
HAVE FUN!
March 29th, 2010 at 2:10 am
my acer aspire 4720
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 don’t output 19 volt but the cable is ok.what testing in dhe board?
April 20th, 2010 at 12:27 am
I think all of them written the input voltages of inverter. i need to know about the output of the inverter which is going to the inverter on two wires ( Red and White).
what are voltages available on those pins.
Thank You
May 13th, 2010 at 8:35 am
Dead LCD Backlight on Mac Powerbook G4 Aluminum 17″…
OK, so I’m pretty handy with my Powerbook. In the past, I’ve replaced 2 different hard drives, a DVD-R drive and a few other things. In short, I’ve torn my Mac apart and put it back together successfully on numerous occasions. By this latest problem has really stumped me. I’ve read up on everything I can find on the Internet and changed out many parts, but still my LCD backlight is dead. Here is what I’ve done so far…
1) First, I assumed it was the Inverter board, so I ordered a replacement, opened up the screen (man, that was a bear) and installed it. Still, no backlight.
2) Next, assumed it was the inverter cable. Repeated above process with new cable. No light. But old cable was damaged (one wire broken), so it seemed like that was a clue. But still no light with new cable.
3) Next, assumed it might be the backlight itself, so I ordered one (complete with compatible 2-pin connector so no soldering needed). I didn’t actually install it (which is an even bigger bear than lid removal), but I did plug it into the inverter output to test it out and… you guessed it… no love.
4) I figured that somewhere along the way, I burned out the replacement inverter board that I bought (OK, I put a meter across the outputs). So I bought ANOTHER replacement inverter. Plugged it in, powered it up… still no backlight (I tried it first with the new replacement bulb just in case original bulb was shorted out).
I have since tested the outputs of the Inverter using the “new Morris Rosenthal technique” outlined in this article above (Harbor Freight meter on kHz setting and probes an inch or so away acting as antennas). When I do that, I get no frequency reading at all on the meter (0 kHz). But, as he said, maybe this is a high frequency inverter and the meter can’t sense frequencies that high.
At this point, I am completely stumped. I checked the input voltages to the inverter board and the seem OK, although I can’t find anything on the Internet that states exactly what they should be. But they aren’t zero (at least not all of them). Here’s what they are…
Silver wire (pin 1, perhaps): 0V
Blue wire (2): +5V
Gray wire (3): 0V
Black wire (4): +12V
Green wire (5): hardwired to ground
So, I’m in for about 90 bucks so far in parts and the thing is still dead. Oh yeah and, by the way, I know it’s the backlight because I can see faint images on the screen AND the laptop works fine when connected to an external monitor. I already have a newer MacBook Pro that I use for everyday stuff, but it would really be nice to get the old G4 working again. Anyone have any suggestions about where to go from here?
John
May 18th, 2010 at 3:25 pm
OK, I solved my own problem… sort of. The bottom line was that the logic board was NOT outputting any voltage for the “dim control” input to the Inverter board. According to some other info found on the Internet, the “dim control” pin should have a voltage ranging from 0 to +4 volts depending on the dimming desired (where 0V = no light, 4V = max light). Since the logic board wasn’t outputting any voltage on that pin, the backlight remained off. So, since I had no intention of buying a new logic board for such an old computer, I decided to just manually put +4V on the pin. Here’s how I did it…
First off, the CORRECT pin names and voltages to the input connector of the Inverter board are here (again, this is for Powerbook G4 17″ Aluminum). This is slightly different than what I wrote in my original message…
CHASSIS GROUND – Green wire (connector pin 1): Hardwired to chassis ground
+12V SUPPLY – Black wire (connector pin 2): +12V
CABLE GROUND – Gray wire (connector pin 3): 0V
+5V SUPPLY – Blue wire (connector pin 4): +5V
DIM CONTROL/ENABLE – Silver wire (connector pin 5): 0 to +4V depending on dimming
So, it was the DIM CONTROL that was dead from the logic board. I had both 12v and 5v available to me at the input connector to the Inverter board so, at first I figured I’d just connect the 5v to DIM CONTROL. At first it worked but, after about 1 minute, the backlight would shut off, presumably because the Inverter was being “overdriven” and it has some kind of overcurrent shutdown circuitry. So, I went to plan B and, though experimentation, found that a 3K ohm resistor placed between pin 4 and pin 5 brought the voltage on the DIM CONTROL to +3.8V which kept the backlight bright without it shutting down. See pictures below.
Now, for the bad news. Not only will the screen not dim (which I can live with), but it also won’t shutoff when going into sleep mode (the display goes away, but the backlight remains lit). For the record, it DOES shutoff when the computer is ShutDown. But, this poses yet another challenge. Since I generally only use my computer from home while it is plugged in, I may not worry about this one for now. But, for many people, this might be a showstopper. None the less, I did get the backlight working.
John
http://www.djjohnnymac.com/images/IMG_4329.jpg
http://www.djjohnnymac.com/images/IMG_4330.jpg
http://www.djjohnnymac.com/images/IMG_4331.jpg
June 16th, 2010 at 7:32 pm
i have a ze4610us i replaced the lcd inverter 4 times and not working, cn1 is pin1-0 pin2-5.11 pin3-3.31 pin4-3.73 pin5-0 ant one know were on the we i can find out what the pin input volts are?