Mid 2006 / model number A1181 / black or white case / 1.83 or 2.0 GHz Intel Core Duo processor.

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No backlight, tried inverter, what now?

hey guys,

I've tried to fix my problem on my own by following the guide instructions of ifixit. I am having exactly the problem which is described in the Macbook troubleshooting article (The screen is very dark, but everything else seems to be running. If you get in close with a flashlight, you can usually see the image faintly.)

So I bought a new inverter but this did not solve my problem. In my case the backlight is available for 10 - 30 seconds and after that the screen is black and I am only able to get the backlight back for 1 second.

I want to know if connecting my Macbook with an external display via vga and getting an image on the new display...

what would that mean? A working logic board and thus a faulty LCD?

My Macbook is just 3 years old and it would be a disaster for me, when having a faulty logic board. Unfortunately I have not bought an ACPP.

I hope you guys can give me some advice!

Update

Thank you for your help!

I have ordered a minidvi to vga connector and I will check if I am getting a good picture on the external monitor.

Changing the inverter cable was actually not an option for me because I first went to an Apple Service Provider and he told me that the cable couldn't be the problem. Due to the fact that the backlight is gone without moving the display.

But now I will try a new inverter cable!

Maybe it's worth to tell the whole story how the backlight problem started:

My Macbook had only 1 GB of memory and I bought new 2x2 GB of memory. But one of those new memory was faulty. I checked it with rember. Afterwards I upgraded to Snow Leopard and while installing the new OS the backlight was gone. But it was possible to get the backlight back by closing and folding up the display. I decided to switch back to the old memory and downgraded to Leopard but this did not solve my problem.

Yesterday I observed that when using the brightness keys( F1 & F2) I can create for one second backlight. I have to switch down the brightness to zero and then by pressing F2 I can get the backlight back. I repeated this key combination in order to maintain the backlight but then I get a flickering backlight, which only lasts for 3 - 4 seconds before getting a screen with no backlight.

I will post here again when I tried the external monitor/ inverter cable!

Update

So the VGA connector arrived and I am getting a good picture on the external monitor!

Today I observed that the backlight of my Macbook was able to last for more than 30 minutes! But afterwards same problem again.

LAST Update

NO LUCK with the new inverter cable :(

First it seemed to be fixed, since the backlight was available during moving the display which was not possible before. But the backlight was gone after a couple of minutes and did not come back. I also changed the inverter board again but no effect... the inverter board which I ordered for replacing my old inverter was even "worse". Because my old inverter was able to produce backlight for a couple of minutes and the new inverter only few seconds...

Answered! View the answer I have this problem too

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9 Answers

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Connecting to an external monitor isolates the problem to the screen area and verifies the logic board. Since you can see the desktop and replaced the inverter, I would replace the inverter cables.

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Cellers, the backlight is part of the screens area. I've never seen a bad logic board that produces a good picture on an external monitor. I suggested replacing the cables. You're getting real nasty downvoting this one. If you don't like the way I worded it, post your own answer. We try to reserve the down votes for really bad answers.

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Backlight issue has nothing to do with the graphic chip so connecting to an external monitor is not a trouble shooting step in this case.

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mayer, lemerise - I disagree. I have seen this issue. Took a suspected bad logic board and out it into a fully working A1181 (LCD, cables) and voila it doesn't work. Put back the original logic board and presto it works. I admit it's strange, but it's not the first time I've seen this.

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If you can get the screen lightning while opening and closing the display then the problem is a damaged inverter cable. If not then the issue is probably the logic board since the inverter board was replaced without solving the problem.

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after closing and opening the display the backlight will come back for less than a second. unfortunately i have to wait about 2 weeks for the new inverter cable... I will post here again when I replaced it.

thanks again for your help guys!

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Hi to everybody!

I had the same problem that you described: backlight on only for 1 sec when using the F1 and F2 keys. sometimes 30sec on, and then off.

I tried to:

-change the inverter- Nothing changed

-change the inverter cable- Nothing changed

I CHANGED THE LCD LAMP and now it's working fine!

So the problem was just the LAMP.

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What is an LCD lamp?

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Mayer, with all due respect, I beg to differ. I have one now in my shop with this problem. Logic board is working fine, external video is working fine, but backlight is NOT working. I swapped the logic board for a known good A1181 board (therefore re-using the old LCD, cables, etc.). In my case, the problem *IS* on the logic board. The logic board is to be repaired or replaced. Unfortunately, I don't see another way around it. I admit this is only the second time I've seen this, so it is rare, but I can confirm it *IS* a real problem.

So is there a trick to repair of the logic board in this case?

I'm putting this here in case someone, like me, already exhausted all other t-shooting. Fortunately, I have 2 A1181's and was able to install a working logic board to confirm that all cables and accessories are all working. The A1181 with suspected bad logic board seems to have a problem. Even wiggling the "backlight" cable going to the upper-left socket on the logic board also did nothing. Again, swapping in a confirmed good logic board into this machine solves the issue, but I'd like to find a cheaper solution if anyone knows of one.

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Ahem, I beg to differ with the need for logic board replacement. Please see some of my other post on the A1181 backlight issues - for troubleshooting and testing. You will find pinout voltages etc... I can confirm the problem can be on the motherboard. I can also confirm if the problem is there, it is most likely a CHEAP fix and not a logic board replacement.

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Hey guys, I have replaced the LCD and now the backlight is working again :) On the highest level of brightness the display is not flickering, but when lowering the brightness I can see it flickering on the display. Is it the inverter??

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MacUser, did you purchase your LCD new or used? In general, flickering is associated with the CCFL bulb (backlight bulb), but it could also be a function of the circuitry delivering the voltage to the inverter. The inverter itself should not be the cause of it.

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@ ABCellars - Good points about the pinouts, voltages, etc. I understand those are all secret! ;-) I should have been more clear that I was looking more to confirm the problem on the logic board DOES exist in case someone else was banging their head against the wall as I was the first time I saw that problem. :-) Also, please POST a link to the article you're referring to. I looked on A1181 and could not find the article you were referring to.

However, if anyone else is looking at this problem for the first time, I did find the iFixit troubleshooting guide to be pretty helpful in diagnosing, and in my case, confirming what I stated above:

MacBook Model A1181 Troubleshooting

So if you have another trick up your collective sleeves, please by all means post and help. :-)

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ABCellars, the LCD is new! So it should not be a CCFL bulb issue, how can I check the function of the circuitry?

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Buy an entire screen assembly sometimes you can get them for $20 ....but don't buy it if it's over 100. Or broken macbooks sometimes sell for very very cheap on ebay and you can take that screen or use new one.I'm just about to sell my screen assembly, last time I tried it I got vertical lines ( worked on external so not logic board issue) Possibly wrong fit with my computer. With the clutch cover housing the inverter and inverter cable the chances of breaking it are very high. As a last resort maybe make sure cables are plugged in properly on back of screen and that the inverter cable and display cable are not stressed by the hinges ( if you take it apart you can see that they basically rub along the hinges) also that the inverter cables are properly plugged into inverter.

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I have bought an entire screen assembly and everything has worked again. So I concluded that the old LCD screen was the cause. The old LCD was replaced by the new one and my assumption was right and the backlight issue has been solved! But be aware of the right model number ;-)

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The answer to this is it has a dry joint on the logic board due to the fan being dirty and the panel running a bit too warm. You can search for instructions as to pulling it apart and what you need to do is remove the top. Mark the screws as they come out otherwise you will be lost.

Next clean the unit remove the fan and clean that.

If you have top quality heat transfer paste its easier to clean if you remove the heatsink as well. DO NOT take the heatsik off unless you are able to clean off the old paste and replace it, or switch on without the heatsink.

Now with a clean unit, look for the plug on the left marked backlight, its near the top left corner. Down a bit, and in a bit, is a brass springy thing which I suspect is an earth for the touchpad. Now look across left, and near there is a tiny transistor. From the plug there is a small IC perhaps 4 pins one side and 2 the other, and below that is this transistor a 3 legged thing about 1mm square with the 1 leg side towards the screen.

That is dry jointed. With a fine pointed soldering iron press down on each leg and the job is done. Rob.

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Have the same problem, backlight comes on for a second when brightness (F1) is down and then press (F2). Earlier backlight would come on when moving screen up and down or closing it and oppening.

Have been told at Apple that LCD and inverter are OK. they did not mention any cables, but suggesten a new logic board £330.

Has anyone solved the problem cheaper? Should I get new Inverter cable (left side on logic board - very tiny) and "video" cable (right side on logic board - huge, complex cable).

Any advice appreciated.

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You need to ask your own question to get proper attention. Since the backlight would come on by moving the screen up & down, the inverter cable is bad, left side. Start by replacing it. The cable on the right has nothing to do with the backlight on this system. I don't buy that Apple could/would test the CCFL bulb in your your LCD (the backlight). If replacing the cable doesn't solve the problem, replace the LCD next. Please see my answer backlight goes out every time open the screen. for pin out voltages on the motherboard and testing the system. Also see the comments to Ty the Tech Guy in this thread.

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