MacBook Pro Unibody - No Backlight - Logic Board Question

[mariusss777]

Need schmatic for MBP early 2011 A1278

Hi, i'm having a mbp early 2011 i5 A1278 with cofee spills that has no light and want to ressurect.
Everything seems to be ok after cleanup only no led light, tested on another working machine.
I',m having an burnt ?fet? on pcb in wich i was able to read on another mbp "KNP Y9" and i desperately need schematic to sort what part it is and didn't found anything until now.
I know here are some users that do have the schematic so i'll gratefully request to them a reply on PM to me if they have 2 spare mins to link me to that!
Cheers for this great thread!

 

[cmdrdata]

Hi, i'm having a mbp early 2011 i5 A1278 with cofee spills that has no light and want to ressurect.
Everything seems to be ok after cleanup only no led light, tested on another working machine.
I',m having an burnt ?fet? on pcb in wich i was able to read on another mbp "KNP Y9" and i desperately need schematic to sort what part it is and didn't found anything until now.
I know here are some users that do have the schematic so i'll gratefully request to them a reply on PM to me if they have 2 spare mins to link me to that!
Cheers for this great thread!

I don't have a late model A1278 schematic, but these folks may have it: http://notebookschematic.com/?cat=489 for a fee, of course.

 

[mariusss777]

Thanks cmdrdata for help but that one is from 2006 and i need for A1278 2011 i5/i7 model, so anybody willing to help me with service manual or schematic for this particular model is very welcomed!
Cheers!

 

[cmdrdata]

Thanks cmdrdata for help but that one is from 2006 and i need for A1278 2011 i5/i7 model, so anybody willing to help me with service manual or schematic for this particular model is very welcomed!
Cheers!

On their website just enter A1278 in the search box. I gave you the generic link. You gotta do a little work to get there.

 

[mariusss777]

yes I did that too but i'm not so sure that i'm gonna get what i need and loose some money, so still searching for a freebie , thanks tough

 

[l.a.rossmann]

I spent forty minutes working on a liquid damaged machine with no backlight only to find the f1/dim key was the only keyboard key stuck down. Wow. Feeling like a total moron right now.

Hopefully someone else is helped by me publicizing my idiocy.

----------

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.

That video makes QFN soldering seem much less frustrating than it actually is on an Apple motherboard. It's as if the pads are somewhat recessed on Unibody boards, solder does not get to or stick to them easily, especially on QFN packages. If you do decide to follow this video, friends, please do it on some dead computer lying around before you try it on your own. It's an incredible pain in the ass to get solder to stick to the pads, and an even bigger pain in the ass getting the chip to actually make contact on all 24 pads. The hell if it aligns itself by itself either, watch as you solder!!

 

[numnutz2005]

Hey guys...were my pics posted earlier good enough?? Ne ideas where its located?? Cause from what i can see the 17in a1297 2011 mbp doesnt have a white dot on the fuse like previous generations which makes it harder to figure out on my end so im hopin others have some advice for me cause i cant set this thing up until its figured out or replaced and at 800 for a new board i rather donate some to someone that isnt tryin to azz rape me callin themselves geniouses (sorry apple lol).

 

[cmdrdata]

Hey guys...were my pics posted earlier good enough?? Ne ideas where its located?? Cause from what i can see the 17in a1297 2011 mbp doesnt have a white dot on the fuse like previous generations which makes it harder to figure out on my end so im hopin others have some advice for me cause i cant set this thing up until its figured out or replaced and at 800 for a new board i rather donate some to someone that isnt tryin to azz rape me callin themselves geniouses (sorry apple lol).

Some fuses (depending on manufacturer) may not have a dot but a letter code that describe it's current limit rating. The one marked in the attachment maybe the fuse you're searching for. A "P" I believed maybe an indication that it is a 3A rated fuse.

 

[CoolDaddy]

Any thoughts on the pictures I posted before of the cable? Think it is damaged?
Thanks

 

[JS4000]

Hi guys, great thread on display/backlight troubleshooting!
My gf's macbook pro 13" early 2011 got a bad coffee spill and I cleaned down the logic board using alcohol and a toothbrush, thank god its now booting but no backlight!
i have uploaded a pic for reference, the chip in the top middle (3legs a side) must have been blown or I may have knocked it off during the cleaning!
Display is def working as with a torch I can see display alive,
Could someone please advise me as to what the part-number is or where one might get a replacement part to re-solder on?

The logic board part number is 661-6078
The part I am referring to is this one -----------↓
Any help appreciated!

 

[numnutz2005]

Some fuses (depending on manufacturer) may not have a dot but a letter code that describe it's current limit rating. The one marked in the attachment maybe the fuse you're searching for. A "P" I believed maybe an indication that it is a 3A rated fuse.

Unfortunately that isnt the fuse at least not in my case . My display works that i know since i tested with 2 other mbps pf the same model and year and the display shows a picture it just doesnt light up. Theres an efi password on the unit but i can remove that no prob but i wanna see what im doin on the screen just in case i need to red some message or whatever else lol. Its usually not so hard to figure this stuff out but apple seems to wanna make it difficult starting this model on....but nothin i can do i guess.

 

[megapt]

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.

can you post a picture with the common components signaled, I got confused with your different postings
thanks

 

[yair27]

Hello all,
i have macbook pro A1286 820 2565-A.
it was with water damage, i was clean all and everything and its work fine i heard the sound of the power up but no display.
i was connect the screen to diffrent working macbook and the screen is fine..its somthing with the ic's(i think)
i dont find any schemes for this board..someone can help?
Thnks!!

 

[McArthur79]

missing parts

Hi,

On a corrosive 13" mid 2009 MBP I've found two locations with missing components. The one marked on the lower right hand side must be the 2A fuse(correct me if it isn't so). I have no idea about the one on the top left hand one. I tried to compare that with pictures from other website but they are often too small and too low in resolution. Can some more advanced users here help me to identify this component,please? Thanks in advance.

 

[McArthur79]

missing parts

This picture gives a better idea about where the missing parts are located. I think a schematics might be needed for this for even if one open up the computer see the part but still not knowing what it is.Please help.

Peter

 

[McArthur79]

missing parts

Sorry, forgot to upload.Hope it works this time.

 

[G35C]

1) One of the things I love about Macbooks is the way they look. Nice clean lines. No ugly vents on the side or bottom. However, do you ever wonder where it gets its air for the fan? Through the keyboard. So if you spill on a working Macbook it sucks the liquid straight down onto the logic board. This may be less of a problem for a laptop that draws air from side vents.

Then a keyboard overlay would be a bad idea as it would block the fan airflow.

 

[ariethekid]

I don't know if that is accurate, because the backlight for the keyboard covers the openings on the keyboard. I think it pulls in air from the vents where the fan is. I think half is for exhaust air and the other half is for intake air.

 

[Dadioh]

I don't know if that is accurate, because the backlight for the keyboard covers the openings on the keyboard. I think it pulls in air from the vents where the fan is. I think half is for exhaust air and the other half is for intake air.

Yes. Thinking about it I think I was mistaken in my original view. That would explain why my brief experiment with a silicon keyboard cover did not significantly increase temps.

That being said, direct spills on the keyboard are the leading cause of death to Macbooks in my opinion (and experience).

 

[dcutty]

@ Dadioh

Dear Mr. GoTo-I have a late 08 macbook pro 15" that I got as a craigslist special (that also came w 2 logic boards) and I've read all the threads that have to do w my problem but I dont see any pics or schematics that look like my model..... So the backlight wont come on and I have taken out the logic board but I dont know which part to test; I dont see the small fuse w the dot or p on it. Also there is a portion on the pack of the board that has a glob of solder next to a component so I'm a bit freaked out!!!

 

[elitetek]

macbook pro WLED driver location?

Just wanted to thank everyone once again for all the great info. Well I have macbook pro logic boards that suffered liquid spills. All three had blow pins on the LVDS cable and connection. one had a blown led fuse which was replaced. I did perform a OHM check on the LED fuse on all the boards and no open connections were detected. However I am still getting no LED backlight. Now I suspect the WLED drivers need to be replaced. However if the WLED driver has failed wouldn't blow the backlight fuse? I have attached the pictures of the logic boards. Any help to where the WLED is that would be great.

2 x MacBook Pro (13-inch, Early 2011) -#820-2936-A
1 x MacBook Pro #820-2530-A

 

[elitetek]

UPDATE:

Maybe it's time to contribute a little on this large forum I found the WLED driver on MID 2009 Macbook pro 820-2530-A, I included the picture and location of it. I also include the link from Digikey with the part number. However I am still unable to locate the WLED drivers on the 2 x MacBook Pro (13-inch, Early 2011) -#820-2936-A. Any help would be great.

 

[elitetek]

national LP8550 location

Does anyone know the location of the WLED driver on logic board 820-2936-A. Can someone please confirm that it uses the national LP8550 IC? I have attached a link below.

http://www.digikey.ca/product-search/en?x=17&y=18&lang=en&site=ca&KeyWords=National+LP8550

 

[naKruul]

you can order the lp8550 directly from national as a sample free of charge.

btw it's the chip right next to the LVDS connector (left of it) - 25 Pin microBGA

 

[elitetek]

Thanks nukruul for the reply. Question is now is the LP8550 difficult to replace? I do have some experience soldering and reflowing. Any help would be great