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 Post subject: no backlight after LCD replacement!!
PostPosted: Tue Sep 08, 2009 7:06 am 
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Joined: Tue Sep 08, 2009 7:03 am
Posts: 5
Hello, I am replacing the LCD on a 15" 2.2ghz MacBook Pro Core 2 Duo (A1226) for a friend who broke it when it slid off the bed. I have done this repair on various models many times, including this one. I am having a problem with the backlight.

First when I put the new LCD in (from PBM), there was no backlight. Checked the inverter cables, reset the PMU, tried again. Nothing. Had to hold a light behind the screen to see the desktop. So to try and problem solve, I plugged the old LCD back in. It had a big crack in it but it worked otherwise, backlight and and all. Now nothing! :shock:

My first thought was that perhaps the inverter had been shorted somehow. Upon further testing, I did notice it got almost too hot to touch. So I ordered a new inverter which arrived yesterday. And just to be extra safe, I swapped the new LCD (with PBM)...just in case it was just defective or something.

Feeling optimistic last night, I tried again, new LCD, new inverter and still nothing! I ran an ASD, which just passed. I am considering ordering a data display cable but the picture is fine (just dark!) and the cable isn't physically damaged as far as I can tell. I've also made extra, extra sure that this is the correct LCD with the folks at PowerBook Medic.

I need to give this computer back soon! I have a new display cable on the way to be safe but this all seems absurd. Please help!! Thanks :P


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 Post subject: Re: no backlight after LCD replacement!!
PostPosted: Tue Sep 08, 2009 9:46 am 
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Joined: Thu Feb 27, 2003 6:35 am
Posts: 977
The magsafe board is really what powers the backlight on those LED models. You'll probably have to replace that.


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 Post subject: Re: no backlight after LCD replacement!!
PostPosted: Tue Sep 08, 2009 10:17 am 
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Joined: Tue Sep 08, 2009 7:03 am
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But why was it working before? I had to use a 60w adapter as I don't have an extra 85w around to charge but whenever I try to turn it on, I have put the battery back in as well. Thanks!


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 Post subject: Re: no backlight after LCD replacement!!
PostPosted: Tue Sep 08, 2009 12:32 pm 
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Joined: Tue Sep 08, 2009 7:03 am
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I don't mind buying one from you guys if you think that will fix it....I just need to understand how that happened to make sure it doesn't happen again. Thanks for your help.


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 Post subject: Re: no backlight after LCD replacement!!
PostPosted: Fri Sep 18, 2009 4:18 am 
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Joined: Tue Aug 25, 2009 4:21 am
Posts: 21
The magsafe board is really what powers the backlight on those LED models. You'll probably have to replace that.

I have the same problem , but the inverter in LED display what do ?
It' s not responsible for the backlight ?


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 Post subject: Re: no backlight after LCD replacement!!
PostPosted: Tue Sep 22, 2009 11:19 am 
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for LEDs, there is the backlight itself which rarely goes out itself, there is the LED driver board which controls the brightness, and then the magsafe board which distributes the power.


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 Post subject: Re: no backlight after LCD replacement!!
PostPosted: Fri Jan 22, 2010 11:25 am 
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Joined: Tue Dec 08, 2009 9:41 pm
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I am having a similar issue with a first-gen CoreDuo 2.16ghz MBP 17" -- I tried replacing the screen and had no backlight (although the video displayed) but crackling that sounded like a short coming from where the inverter board connector cables connect to the LCD ... put my old screen (scratched) back on and it worked fine.

Figuring it was a bad LCD, I RMA'd it and got no backlight with no display and basic things such as resetting the PRAM didn't seem to work. However, once I plugged in an external display and booted, the LCD came on (backlight and all) except the LCD display was completely distorted with purplish vertical lines throughout.

Interestingly enough, if I powered down and disconnected the external display, the gray screen and apple logo now appear on the replacement LCD every time. Once it fully boots however, it's back to the purple lines and I can't seem to fix that.

The frustrating thing about all of this is that my old screen works like a charm with no issues... any ideas?


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 Post subject: Re: no backlight after LCD replacement!!
PostPosted: Mon Jan 25, 2010 10:05 am 
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still sounds like a LCD problem. There may have been a bad batch of them as we and several other suppliers had an incompatibility with those screens for certain model MacBook Pros.


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