06-03-2010, 11:22 AM

Hi there

my slightly old (one before unibody) 17" Macbook pro is having issues with the screen.

The backlight is intermittently off (I can still see the screen image faintly, if a light is shone on the screen at the right angle.)

The screen started losing the backlight about a month ago, I thought it had completely died, but today started up again, only to die once more.

Closing the screen down and opening it back up used to occassionally bring the screen back to life, but not anymore.

Any ideas what could be wrong with this machine? (and how to fix it?)

Many thanks for your advice

ThreeIsles

06-03-2010, 02:51 PM

The backlight may have failed or it could be the inverter board. But it's likely either the backlight or cable to the backlight from the inverter. Changing a backlight is not an easy task on any computer display and usually it's better to just replace the entire display assembly which includes the backlight.

You can get an idea of cost and how to change out the display yourself by going to iFixit: The free repair manual. Look up your model MBP and find the step by step instructions for swapping the display.

If your MBP is still covered by warranty (Apple care) take it on in to your local Apple store and let them repair it.

Regards.

06-03-2010, 03:14 PM

My 17" MBP unibody does this once in a while coming out of sleep. I have to put it back to sleep and wake it again to get the screen to come on normally again. I am thinking it is a software problem.

06-04-2010, 04:27 AM

Thanks

chscag, any idea of predicting whether it is the cable or the backlight or the inverter board? (What does the inverter board do?)

Given then tempermental nature of the fault (mostly off, occasionally on, but then goes off after a minute or two) what would beyour guess?

Many thanks,

ThreeIsles

06-04-2010, 12:31 PM

The inverter provides the power for the backlight. From your description of the problem it sounds like it could be the cable connector which may be loose making intermittent contact. But then again, it could be a flaky backlight. The backlight on your machine might be the CCFL type which have a shorter life span than the more modern LED ones that are now used. You can learn a bit more about the backlight from this wiki article.

Regards.

06-06-2010, 01:20 PM

This could be 1 of 5 problems. I will list them in order of likelihood, from most likely to least likely.

a) Bad inverter board. The inverter board takes a low DC voltage and turns it into the high AC voltage necessary to power the backlight on CCFL backlit machines. This is most likely. A CCFL bulb does not go in and out. Typically it either fails completely, or the colors get ruined until it finally fails. It's not like the flickering street lamps you see. In my experience, when it works one second and doesn't the other, it's the inverter board at fault.

b) Bad screen backlight. This is what lights up your screen so you can see what is on it.

c) Bad I/O board. This is a component separate from the main logic board that supplies power to the inverter board. It is to the left of the main logic board and is where the airport card for wifi plugs into, as well as USB. Wifi and backlight occasionally go hand in hand in my experience. Is your wifi working flawlessly? If it is, lower the likelihood of this being the issue.

d) Bad cable from screen to backlight. THIS IS RARE AND ONLY OCCURS WHEN SELF REPAIR HAS GONE TERRIBLY WRONG. Very unlikely unless you have opened your machine before, but I must list it as a possibility.

e) Bad cable from inverter to logic board. This one is rare and only occurs in my experience on the older A1181 macbooks which used a very strange connector piece.

It is most likely B or A. Please attempt to avoid instructions that require you open more of the machine than is necessary to get to the inverter board or the LCD! It is unnecessary and only leads to potential for lost screws and damaged parts. You need only remove the two screws at the bottom corner of the display assembly to get to the inverter board & screen.

edit: On LED backlit LCDs prior to the unibody, there is a backlight connector that may require reseating that is not present on CFFL backlit LCDs from the same machine. I forgot that on the 17" non-unibody Macbook Pro, it is possible to have either a CCFL backlit or LED backlit LCD with the same A1229 model #. Please note the following picture,

http://rossmanngroup.com/img/LEDbacklight.jpg

06-07-2010, 10:46 AM

l.a.rossmann,

thanks for that really helpful post. And thank you chscg for your links and comments.

are the two screws you mention, those on the back of the body of the MBP, beside where the screen joins?

I believe my screen is an LED screen even though it is not a unibody MBP. It is one of the Matt ones.

I believe, from your comments that it is most likely to be the inverter board - hopefully this will be the case as it seems this is easier and cheaper to fix!

Many thanks,

ThreeIsles

05-20-2012, 12:35 AM

My Macbook Pro's backlight went dark. WiFi stopped working as well.
The LCD, Inverter and cable are good. I tested them with other laptops.

It leads to the bad I/O board.

How would I fix or replace the I/O board?

Thank you very much for in advance.

c) Bad I/O board. This is a component separate from the main logic board that supplies power to the inverter board. It is to the left of the main logic board and is where the airport card for wifi plugs into, as well as USB. Wifi and backlight occasionally go hand in hand in my experience. Is your wifi working flawlessly? If it is, lower the likelihood of this being the issue.

Originally Posted by l.a.rossmann

This could be 1 of 5 problems. I will list them in order of likelihood, from most likely to least likely.

a) Bad inverter board. The inverter board takes a low DC voltage and turns it into the high AC voltage necessary to power the backlight on CCFL backlit machines. This is most likely. A CCFL bulb does not go in and out. Typically it either fails completely, or the colors get ruined until it finally fails. It's not like the flickering street lamps you see. In my experience, when it works one second and doesn't the other, it's the inverter board at fault.

b) Bad screen backlight. This is what lights up your screen so you can see what is on it.

c) Bad I/O board. This is a component separate from the main logic board that supplies power to the inverter board. It is to the left of the main logic board and is where the airport card for wifi plugs into, as well as USB. Wifi and backlight occasionally go hand in hand in my experience. Is your wifi working flawlessly? If it is, lower the likelihood of this being the issue.

d) Bad cable from screen to backlight. THIS IS RARE AND ONLY OCCURS WHEN SELF REPAIR HAS GONE TERRIBLY WRONG. Very unlikely unless you have opened your machine before, but I must list it as a possibility.

e) Bad cable from inverter to logic board. This one is rare and only occurs in my experience on the older A1181 macbooks which used a very strange connector piece.

It is most likely B or A. Please attempt to avoid instructions that require you open more of the machine than is necessary to get to the inverter board or the LCD! It is unnecessary and only leads to potential for lost screws and damaged parts. You need only remove the two screws at the bottom corner of the display assembly to get to the inverter board & screen.

edit: On LED backlit LCDs prior to the unibody, there is a backlight connector that may require reseating that is not present on CFFL backlit LCDs from the same machine. I forgot that on the 17" non-unibody Macbook Pro, it is possible to have either a CCFL backlit or LED backlit LCD with the same A1229 model #. Please note the following picture,

http://rossmanngroup.com/img/LEDbacklight.jpg