MacBook Pro Unibody - No Backlight - Logic Board Question

[sbddude]

are you sure it's not stolen? with my undercover anti-theft i can make it fake a hardware failure with the screen not turning on.

so when it's taken to an authorized apple center, they can tell it's been stolen.

How do you do the antitheft thing?

 

[Dadioh]

@Dadioh,

I have been aiming my efforts at the QFN package also until I came upon this thread. I have a fuse (closed) on the MB but it's not as small as described above. Can you give me a description of where about on the MB you found the tiny fuse. I'm at my macbook for at least two weeks now with no luck. Tks.

See image below. This is a 2A fuse in an 0402 package. I think it is 16V but can't remember. It carries 12V normally. Look for the little white dot on the top. Use a multimeter and check if it is an open circuit (unplug the battery first).

 

[Dadioh]

@Dadioh,

I have been aiming my efforts at the QFN package also until I came upon this thread. I have a fuse (closed) on the MB but it's not as small as described above. Can you give me a description of where about on the MB you found the tiny fuse. I'm at my macbook for at least two weeks now with no luck. Tks.

I can probably give you a few pointers on determining if your WLED driver is blown. I have documented the impedance to ground for all the pins on a good part so you could use a multimeter to check if something is shorted internally. I have had 3 different MBP 13 with blown WLED drivers so far. The part has a boost circuit that puts out 27V (full brightness) so it is VERY susceptible to liquid spills.

The bad news is these are almost impossible to solder

PM me if you want some help.

 

[duxzero]

Would be great if you could point me in the right direction in how to go about checking the WLED driver with a multimeter. I have reballing equiptment (hot air gun, preheater etc) I've never done QFN before, but I guess QFN packages could be done about the same way as BGA's.. (it's not possible to pm you btw.. guess your profile setting does not allow it, but feel free to pm me back).

 

[Dadioh]

Would be great if you could point me in the right direction in how to go about checking the WLED driver with a multimeter. I have reballing equiptment (hot air gun, preheater etc) I've never done QFN before, but I guess QFN packages could be done about the same way as BGA's.. (it's not possible to pm you btw.. guess your profile setting does not allow it, but feel free to pm me back).

PM me and I will try and get you sorted out.

 

[duxzero]

PM me and I will try and get you sorted out.

For some reason I'm unable to PM, don't know if it's my newly registered account that has restrictions or what it can be. Anyway, could you just email me? My email is the nick I have here + @gmail.com... Would greatly appreciate it.

 

[RC357]

Tooling Up

Greetings to all the thread contributors and special thanks to Dadioh, not only for starting this thread, but also for being so kind and helpful in subsequent contributions.

I am having this problem with my Mac also. What tools are required to replace this fuse? I have some soldering experience but never anything this small. I have found some information about how to purchase them and it looks like there might be a kit that will help... Any advice on the tools / techniques for removing / replacing this item is greatly appreciated.

 

[micco]

Thanks for all the info!
My 13 mbp suffer from the same thing - coffee spill.
Back light is gone, but still usable from an external display.

Looking for more info on how to test the fuse. I have a multimeter, but not 100% sure on the setting to use and where exactly to test.

Info would be greatly appreciated!

cheers

 

[Dadioh]

Greetings to all the thread contributors and special thanks to Dadioh, not only for starting this thread, but also for being so kind and helpful in subsequent contributions.

I am having this problem with my Mac also. What tools are required to replace this fuse? I have some soldering experience but never anything this small. I have found some information about how to purchase them and it looks like there might be a kit that will help... Any advice on the tools / techniques for removing / replacing this item is greatly appreciated.

I use a stereo microscope and a very fine tip on my Haako soldering iron. Unless you want to get into regular fine soldering that would be overkill for you to purchase. Might be better to find someone local who can do it for you.

 

[micco]

I use a stereo microscope and a very fine tip on my Haako soldering iron. Unless you want to get into regular fine soldering that would be overkill for you to purchase. Might be better to find someone local who can do it for you.

Just wondering if you would be kind enough to provide some diagnostic info to help determine the issue on my mbp?

Did you sucessfully repair yours?

In you original picture circled the white box, mine has some discoloration in the center. I took my multimeter and checked if current can pass through and no luck.
I did the same to the tiny fuse you circled and i heard a beep - indicating there was no break. I'm not too sure on what you mean by "open circut", but i'm assuming it's an incomplete connection.

thanks

 

[Dadioh]

Just wondering if you would be kind enough to provide some diagnostic info to help determine the issue on my mbp?

Did you sucessfully repair yours?

In you original picture circled the white box, mine has some discoloration in the center. I took my multimeter and checked if current can pass through and no luck.
I did the same to the tiny fuse you circled and i heard a beep - indicating there was no break. I'm not too sure on what you mean by "open circut", but i'm assuming it's an incomplete connection.

thanks

The white device is a capacitor. It will not pass current so it will show as an "open circuit" (that is your multimeter will show a large value for resistance in the megaohms or more). Some multimeters (like my Fluke) can do basic capacitor measurements but most cheap ones will not. However, the capacitor is not likely to be the source of your problem.

If you measured across the fuse and the meter "beeped" then it means the fuse is good. However, that is not good news. The fuse is a relatively easy fix (with some decent soldering skills). I have had 3 cases of this circuit having a blown WLED driver. That is the square black package down and to the right of the white capacitor. That is a 24 pin QFN package and they are VERY DIFFICULT to replace. The part is relatively cheap however. If you buy the part you will need to find a professional to remove and reinstall the new one. This is not the sort of job someone new to soldering is going to learn very quickly. If you want a sense of it just search on "QFN Soldering techniques". Here is one example below.

http://www.youtube.com/watch?v=c_Qt5CtUlqY&feature=fvw

There is also the possibility that it is not the WLED driver and some other circuit inputing to the driver (like the enable pin) but the most likely cause is blown WLED driver.

Hope that helps.

 

[Dadioh]

Thanks for all the info!
My 13 mbp suffer from the same thing - coffee spill.
Back light is gone, but still usable from an external display.

Looking for more info on how to test the fuse. I have a multimeter, but not 100% sure on the setting to use and where exactly to test.

Info would be greatly appreciated!

cheers

Just on a side note you need to take the time to really clean off all of the coffee from the board. Even if it is "working" (minus the backlight that is) the coffee, if left to its own devices, will continue to corrode the board until it dies completely. You need to remove the logic board from the Macbook and use some 99% isopropyl alcohol to clean off the areas of the board that have coffee residue. A toothbrush works quite well (make sure it is a new one of course

 

[micco]

The white device is a capacitor. It will not pass current so it will show as an "open circuit" (that is your multimeter will show a large value for resistance in the megaohms or more). Some multimeters (like my Fluke) can do basic capacitor measurements but most cheap ones will not. However, the capacitor is not likely to be the source of your problem.

If you measured across the fuse and the meter "beeped" then it means the fuse is good. However, that is not good news. The fuse is a relatively easy fix (with some decent soldering skills). I have had 3 cases of this circuit having a blown WLED driver. That is the square black package down and to the right of the white capacitor. That is a 24 pin QFN package and they are VERY DIFFICULT to replace. The part is relatively cheap however. If you buy the part you will need to find a professional to remove and reinstall the new one. This is not the sort of job someone new to soldering is going to learn very quickly. If you want a sense of it just search on "QFN Soldering techniques". Here is one example below.

http://www.youtube.com/watch?v=c_Qt5CtUlqY&feature=fvw

There is also the possibility that it is not the WLED driver and some other circuit inputing to the driver (like the enable pin) but the most likely cause is blown WLED driver.

Hope that helps.

Thanks for the Info - much appreciated.
Although this really isn't the news i wanted to hear
The QFN replacement is well beyond my abilities...and probably not worth fixing.

Lower on the board theres another white capacitor similar to the one by the display harness. That one (assuming its the same) i was able to confirm it was not an open circuit. My cheap digi multimeter sounds a beep when testing for open circuits.

This mbp was previously taking into a repair shop for cleaning - i'm assuming they clean it out, but i'll def take your recommendation and brush it up with iso.

Do you mind confirming/commenting on my lower capacitor findings?

thanks again!

 

[Dadioh]

Thanks for the Info - much appreciated.
Although this really isn't the news i wanted to hear
The QFN replacement is well beyond my abilities...and probably not worth fixing.

Lower on the board theres another white capacitor similar to the one by the display harness. That one (assuming its the same) i was able to confirm it was not an open circuit. My cheap digi multimeter sounds a beep when testing for open circuits.

This mbp was previously taking into a repair shop for cleaning - i'm assuming they clean it out, but i'll def take your recommendation and brush it up with iso.

Do you mind confirming/commenting on my lower capacitor findings?

thanks again!

There are a couple of fuses on the logic board that are also white in color. That is why I originally thought that the white component near the LVDS connector was a fuse. Visually you can not tell the difference.

There will be one 6A fuse near where the magsafe and an 8A fuse after the charger circuit. If they were blown you would have no life on your board at all.

 

[micco]

There are a couple of fuses on the logic board that are also white in color. That is why I originally thought that the white component near the LVDS connector was a fuse. Visually you can not tell the difference.

There will be one 6A fuse near where the magsafe and an 8A fuse after the charger circuit. If they were blown you would have no life on your board at all.

Is there any way i can test the QFN to ensure it is the culprit?

edit: I just finished cleaning the mobo, it actually looked pretty good. The worst was the magSafe board, which i noticed something that may explain why when i plug it in the light on the charger is very faint and osx says "not charging".

would anyone have a working one kicking around

 

[prg]

OK for all the people with no backlight on a macbook pro 15" unibody.

first of all thanks to the man with the schematic....
I take it you have checked the flurecent and inverter allready and both are ok.
on the logic board there is a fuse that supply's the voltage/ currant to the backlight circuit...its F9800.Its located on the board near the botom of the left fan on the component side of the board.(same side that has the cpu and gpu on it).

the fuse is a smd and its white with just a dot on it.get your multimeter and if its open circuit thats you problem.
got mine fixed today...

If you need a hand then drop me a line and i will try to see what i can do...

Had to share this as it took me a good day to put right,,,

good luck.

componentfix

See image below. This is a 2A fuse in an 0402 package. I think it is 16V but can't remember. It carries 12V normally. Look for the little white dot on the top. Use a multimeter and check if it is an open circuit (unplug the battery first).

------------------

Hi I purchased a A1286 of a friend that spilled water, now there is no backlight, other then that the laptop works fine.

Both of you which I quoted about know what your talking about. So if F9800 is bad or Q9806 is bad do I look for those fuses online and purchase the exact one to fix it. How did you guys manage to fix yours. Pictures/videos or good explanation with step by step would be much appreciated!

Thank You.

 

[Dadioh]

------------------

Hi I purchased a A1286 of a friend that spilled water, now there is no backlight, other then that the laptop works fine.

Both of you which I quoted about know what your talking about. So if F9800 is bad or Q9806 is bad do I look for those fuses online and purchase the exact one to fix it. How did you guys manage to fix yours. Pictures/videos or good explanation with step by step would be much appreciated!

Thank You.

This is the fuse that I bought. I think that any fast acting 2A fuse in an 0402 size would be fine.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=478-2857-1-ND

 

[prg]

This is the fuse that I bought. I think that any fast acting 2A fuse in an 0402 size would be fine.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=478-2857-1-ND

Thank you for the link. Now, how did you go about removing the old fuse and installing the new one. I saw the Video that was posted on this forum, but is it possible for me to use a regular soldering iron to fix this problem?

 

[Dadioh]

Thank you for the link. Now, how did you go about removing the old fuse and installing the new one. I saw the Video that was posted on this forum, but is it possible for me to use a regular soldering iron to fix this problem?

I think the best answer is to google "soldering 0402 by hand". There are dozens of guides and videos available. However, soldering 0402 is not for novices. You need a very fine tip soldering iron and a stereo microscope to do a proper job. At least some sort of magnification anyways. If you have an old circuit board I would spend some time practicing on that. Or see if there is someone local to you that can solder it for you.

 

[prg]

I think the best answer is to google "soldering 0402 by hand". There are dozens of guides and videos available. However, soldering 0402 is not for novices. You need a very fine tip soldering iron and a stereo microscope to do a proper job. At least some sort of magnification anyways. If you have an old circuit board I would spend some time practicing on that. Or see if there is someone local to you that can solder it for you.

You are a great help thank you.

These sites I pasted below, do these fuses compare to the link you sent me from digi? Are they compatible with the bored?
---------------
http://www.mouser.com/ProductDetail...=sGAEpiMZZMseCiJT91fwIpRk8cYmTOZANzuslftHqVo=

---------------

http://www.newark.com/jsp/search/productdetail.jsp?SKU=30C5431&CMP=AFC-GB100000001

http://www.littelfuse.com/data/en/Data_Sheets/435.pdf

 

[Dadioh]

You are a great help thank you.

These sites I pasted below, do these fuses compare to the link you sent me from digi? Are they compatible with the bored?
---------------
http://www.mouser.com/ProductDetail...=sGAEpiMZZMseCiJT91fwIpRk8cYmTOZANzuslftHqVo=

---------------

http://www.newark.com/jsp/search/productdetail.jsp?SKU=30C5431&CMP=AFC-GB100000001

http://www.littelfuse.com/data/en/Data_Sheets/435.pdf

Yes. Those are all 2A fast acting fuses in 0402 package so get whichever is convenient.

 

[prg]

Yes. Those are all 2A fast acting fuses in 0402 package so get whichever is convenient.

Thank you for your help. Got the light working!

 

[Dadioh]

Thank you for your help. Got the light working!

Congrats!!!!

Another Macbook rescued....

 

[vw1610]

See image below. This is a 2A fuse in an 0402 package. I think it is 16V but can't remember. It carries 12V normally. Look for the little white dot on the top. Use a multimeter and check if it is an open circuit (unplug the battery first).

i just ordered a replacement fuse off digi key. i cant wait to swap it out and see it working again..

thanks all for making this forum and posting your knowledge.

 

[vw1610]

i just ordered a replacement fuse off digi key. i cant wait to swap it out and see it working again..

thanks all for making this forum and posting your knowledge.

My macbook is working again!!! thanks everyone