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MacBook Pro Unibody - No Backlight - Logic Board Question

Hey, been reading your advice to everyone on here for months and you seem to be the master MAC man haha.. Well I have a question to rattle your brain with.. I'm new to the sight so let me no if we have to open up a new post.. I already posted it on the site but did not ask you personally.. Please let me no what you think I can do or point me in a direction thanks so much.. If you go to that number post on this thread the pics are there..

AplReprMan
#1385 Jul 27, 2013, 11:45 AM

I have a question about this same board from a late 2008 MBP 15" Board number is 820-2532-A

THIS I DON'T THINK IS PART OF THE DISPLAY BUT I COULD BE WRONG, , BUT ITS OBVY DAMAGED FROM LIQUID AND OTHER PARTS AROUND IT.. CAN ANYBODY HELP ME DETERMINE WHAT THIS IS AND WHAT IT CONTROLS??? I'LL MAKE A NEW THREAD TO NOT INTERRUPT THIS ONE AFTER I GET AN ANSWER TO SEE WHAT IT CONTROLS
 
Wled app001a

Hi,

After checking through the threads i see that WLED APP_01 appears to be a custom part and therefore not available and no datasheet. I have a few boards which use this chip where the backlight does not work. On a couple I have found that i do not get 4.9v on BKL_VREF_4V9. After checking out the circuit diagram i am having trouble tracing the source of this signal. I notice on the schematic (currently looking at M97 820-2327) pin#4 says VREF which in-turn links to BKL_VREF_4V9 but is this pin#4 the source of the 4.9v or is it an input and therefore looking for 4.9v to be present on the pin?

Any help would be greatly appreciated.
Rog
 
laptech said:
Hi,

After checking through the threads i see that WLED APP_01 appears to be a custom part and therefore not available and no datasheet. I have a few boards which use this chip where the backlight does not work. On a couple I have found that i do not get 4.9v on BKL_VREF_4V9. After checking out the circuit diagram i am having trouble tracing the source of this signal. I notice on the schematic (currently looking at M97 820-2327) pin#4 says VREF which in-turn links to BKL_VREF_4V9 but is this pin#4 the source of the 4.9v or is it an input and therefore looking for 4.9v to be present on the pin?

Any help would be greatly appreciated.
Rog
Click to expand...

The way I read the schematic it seems that pin 4 of APP001 must be sourcing this 4.9V. I don't see any other potential source. So my guess would be that if you do not have 4.9V then you need to replace the APP001 device. This would require scavenging one from a spare parts board.
 
Dadioh said:
The way I read the schematic it seems that pin 4 of APP001 must be sourcing this 4.9V. I don't see any other potential source. So my guess would be that if you do not have 4.9V then you need to replace the APP001 device. This would require scavenging one from a spare parts board.
Click to expand...

Thankyou for your reply, i had a suspicion it might have been the source. Will have to wait till i get some scrap boards because as i am aware, this is the only board with the APP001 WLED chip on it and i dont have any scrap of them. Oh well.

kind regards
Rog
 
(related to this post)

Hi there,

is my assumption likely to be correct that the WLED driver (LP8550) is dead?

No backlight, 11.42V on PPVOUT_SW_LCDBKLT:

BKL_EN: 2.8V (should 3V) -> OK
PP5V_S0: 4.96V (should 5V) -> OK
PP3V3_S0: 3.25V (should 3.3V) -> OK
FB: 11.42V (should 25V) -> wrong
SW: 11.42V -> possibly OK
PWM: 3.07V -> possibly OK

Resistances to ground (Range 1kOhm-200kOhm):

EN: Inf
SW: Inf
FB: Inf

ISEN1: 58 Ohm
ISEN2: Inf
ISEN3: Inf
ISEN4: Inf
ISEN5: Inf
ISEN6: Inf

The resistance of ISEN1 seems odd.

The board is a 820-2936-A.

Thanks!
 
MCP79 U1400 Northbridge possible cause?

Hi,

Need a second opinion on this issue i am having with no backlight on 820-2530-A K24 boards. I have a few where i do not get any output signal on LVDS_IG_BKL_ON. I have checked the signals on a working board and I should be getting around 3.1v. Having looked at the schematic for the board I found what I believe is the output for this signal coming from the Northbridge IC, U1400. Am i correct in believing that the Northbridge is the output source of signal LVDS_IG_BKL_ON and if i dont have the correct signal then the Northbridge is faulty and i would have to replace U1400?. Or is there another input into U1400 which basically instructs it to enable LVDS_IG_BKL_ON?

Any help would be greatly appreciated.

kind regards
Rog
 

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need help sorting out this display problem

hello everyone, ive read the first 15 pages and couldnt find anything that matched my machine exactly so i figured id make an account and ask you guys specifically for my mac. so i have a mid 2010 mac book pro 15 inch.. i am having the dim display problem as well, you can put a flashlight to it and guide yourself around and also you can hook up an external display and it functions properly as well.. so the computer was accidentally dropped and the screen went crazy there were a bunch of colors i believe and some white spots with black lines.. so i put a new lcd screen in and i got the problem im having now with the flashlight trick.. i returned that screen and got a new screen and still having no back light on the new one either. i changed the lcd cable as well with no luck. i plugged in the OLD DAMAGED screen and now even though that was broken the back light still lit up now that one is dark as well.. i called 4 different computer places around here and they all said i need a new motherboard.. $700 plus.. no way i can afford that now im seeking help from the expert on here (dadioh) but if anyone else wants to lend a hand anything would be appreciated. i can have pics put up of certain parts if need be but as far as i read it looks like i might be having the backlight fuse problem on the motherboard but i am not able to locate it to check can anyone help?? thanks a ton!
 
early 2009 MBP 15" 2.66 ghz no backlight

I am a newbie here and don't know how things are done so please bear with me if I am in the wrong place.

I have been reading these posts all day till my head hurt. Took a nap and came back.

I have a 15" early 2009 MBP (the last removable battery model) that I replaced the keyboard in after liquid damage. The unit still worked but the keyboard was malfunctioning and the display had coffee in it where it was turned upside down after the event. A friend brought this to me to fix and I am capable of that. They also brought a replacement display from a dead MBP.

After the KBD replacement I stupidly connected the (unknown condition) display and killed the backlight. The old display still works (you can see it with a flashlight against the Apple on the lid) but no backlight. I have looked at all the boards here and have yet to be able to locate the fuse.

Attached (i hope) is a pic of the underside of my board behind the display connector with annotations of what I found that might be relevant.

Please help!!

TIA
 

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Hey Dadioh- I have a question. I am getting a bit tired of my computer and want to give an ebay DIY computer another shot. However, most of the deals seem to be on water damaged laptops. I remember seeing a few things on this thread about getting water damaged boards to work. So what do I need to look for in a board if I am going to scrub with 90%+ alcohol (and how likely is it it will work again?).
I'm comfortable with replacing fuses, etc on the boards but probably cannot do an LDVS connector...
 
White dot always a fuse?

This thread has been going on for years now and I imagine Dadioh is getting tired of answering the same questions over and over. (I know I would be)

The location of the famous fuse for the backlight seems to be different for every model. It would be helpful to me and perhaps others to know if the white dot on an 0402 package always denotes a fuse.

Since the little buggar can be in so many locations.

Thanks to Dadioh and all other helpful folks here! :cool:
 
midijamm said:
This thread has been going on for years now and I imagine Dadioh is getting tired of answering the same questions over and over. (I know I would be)

The location of the famous fuse for the backlight seems to be different for every model. It would be helpful to me and perhaps others to know if the white dot on an 0402 package always denotes a fuse.

Since the little buggar can be in so many locations.

Thanks to Dadioh and all other helpful folks here! :cool:
Click to expand...

Lol I bet Dadioh could make a killing fixing just about anything with a logic board now!
 
Please help!

I have gotten myself up the creek with my friends computer.


Can anyone tell me if the fuse indicated in the post a few above this one is the backlight fuse.

I know the resolution is terrible. all I have is an iPhone for a camera but the location is decernable.

It is not very close to the display connector but is the only one I can find with a white dot!

Does a white dot always mean it's a fuse?

Sorry to keep asking but I am drifting here without a paddle!
 
midijamm said:
I am a newbie here and don't know how things are done so please bear with me if I am in the wrong place.

I have been reading these posts all day till my head hurt. Took a nap and came back.

I have a 15" early 2009 MBP (the last removable battery model) that I replaced the keyboard in after liquid damage. The unit still worked but the keyboard was malfunctioning and the display had coffee in it where it was turned upside down after the event. A friend brought this to me to fix and I am capable of that. They also brought a replacement display from a dead MBP.

After the KBD replacement I stupidly connected the (unknown condition) display and killed the backlight. The old display still works (you can see it with a flashlight against the Apple on the lid) but no backlight. I have looked at all the boards here and have yet to be able to locate the fuse.

Attached (i hope) is a pic of the underside of my board behind the display connector with annotations of what I found that might be relevant.

Please help!!

TIA
Click to expand...

That looks like I is probably the right component. I don't have a 2008 15" unibody board to check. A white dot or "F" or "P" on the top as far as I know is always a fuse. Do you have a multimeter to measure this? If it is blown then it will measure mega ohms but I it is good it is 0 or a couple of ohms.

----------

Just got back from a business trip out of country so I will try and catch up with some of these requests for info. I agree that we really need to do mark up photos of the boards with fuse locations and put it on the first post for people to refer to. It would save a lot of searching. This is just a hobby for me and it has ballooned into a demand for my time that is hard to keep up with. I try my best and I am grateful for some of the other people that help out with their advice.

----------
AGTSTi7 said:
hello everyone, ive read the first 15 pages and couldnt find anything that matched my machine exactly so i figured id make an account and ask you guys specifically for my mac. so i have a mid 2010 mac book pro 15 inch.. i am having the dim display problem as well, you can put a flashlight to it and guide yourself around and also you can hook up an external display and it functions properly as well.. so the computer was accidentally dropped and the screen went crazy there were a bunch of colors i believe and some white spots with black lines.. so i put a new lcd screen in and i got the problem im having now with the flashlight trick.. i returned that screen and got a new screen and still having no back light on the new one either. i changed the lcd cable as well with no luck. i plugged in the OLD DAMAGED screen and now even though that was broken the back light still lit up now that one is dark as well.. i called 4 different computer places around here and they all said i need a new motherboard.. $700 plus.. no way i can afford that now im seeking help from the expert on here (dadioh) but if anyone else wants to lend a hand anything would be appreciated. i can have pics put up of certain parts if need be but as far as i read it looks like i might be having the backlight fuse problem on the motherboard but i am not able to locate it to check can anyone help?? thanks a ton!
Click to expand...

If you can post clear photos of the logic board both top and bottom near the lvds cable then we should be able to help you spot it.
 
screen display

Dadioh said:
That looks like I is probably the right component. I don't have a 2008 15" unibody board to check. A white dot or "F" or "P" on the top as far as I know is always a fuse. Do you have a multimeter to measure this? If it is blown then it will measure mega ohms but I it is good it is 0 or a couple of ohms.

----------

Just got back from a business trip out of country so I will try and catch up with some of these requests for info. I agree that we really need to do mark up photos of the boards with fuse locations and put it on the first post for people to refer to. It would save a lot of searching. This is just a hobby for me and it has ballooned into a demand for my time that is hard to keep up with. I try my best and I am grateful for some of the other people that help out with their advice.

----------



If you can post clear photos of the logic board both top and bottom near the lvds cable then we should be able to help you spot it.
Click to expand...

alright here is a link of the back of a board which should be exactly similar to mine.. .http://173.192.77.187/attachment.php?attachmentid=394649&d=1360085025..... the one that is circled in this picture is the right one correct? and if i put a multi meter to each side and it doesnt beep i can be 100% sure that its the fuse thats causing the back light problem correct? thanks again for your help and i dont want to take my mother board off yet, i have a new lvds cable coming tomorrow i wanna try that first to see if itll fix the problem that is why i didnt take pics of my personal comp... but from the information i gave you previously can you somewhat tell if its going to be a fuse problem or do you think it could be sometthing else??
 
Dadioh said:
Just got back from a business trip out of country so I will try and catch up with some of these requests for info. I agree that we really need to do mark up photos of the boards with fuse locations and put it on the first post for people to refer to. It would save a lot of searching. This is just a hobby for me and it has ballooned into a demand for my time that is hard to keep up with. I try my best and I am grateful for some of the other people that help out with their advice.
Click to expand...
Took my late '08 15" logic board out tonight to do thermal paste and took some high def photos of the board (don't ask. My 2hr top case transplant ballooned into a 10 hr repair frenzy, ended up with me breaking my display glass and messing with a loose LDVS cable...). Didn't have anything but an old loupe to catch a photo of the fuse though. Message me if you need em and ill be happy to send them along. I can get pics of a mid 09 15 too in November (when it gets returned). Getting a mid 2010 a1278 from eBay and would be happy to get pics of that too. Shots are with a canon t2i so reasonable quality. My father has some high end optical stuff too, I'll see if I can get really good pics of the fuse and location. I'd be happy to help you get some of this information more organized. Maybe MR would let this have its own page, with better HTML design tools.
 
AGTSTi7 said:
alright here is a link of the back of a board which should be exactly similar to mine.. .http://173.192.77.187/attachment.php?attachmentid=394649&d=1360085025..... the one that is circled in this picture is the right one correct? and if i put a multi meter to each side and it doesnt beep i can be 100% sure that its the fuse thats causing the back light problem correct? thanks again for your help and i dont want to take my mother board off yet, i have a new lvds cable coming tomorrow i wanna try that first to see if itll fix the problem that is why i didnt take pics of my personal comp... but from the information i gave you previously can you somewhat tell if its going to be a fuse problem or do you think it could be sometthing else??
Click to expand...

That would be the fuse. The fuse blows when too much current flows due to a fault. If the fault was due to a liquid spill and cleaning the board removed the fault then you should be good. After removing the old fuse take a second to check the resistance measurement from the fuse output to a ground point. If it is a low number, say less than 100ohms, then you still have the problem and a new fuse would just blow again. In that case you would have some detective work to find the fault. But most of the time, if the spill is cleaned and if the lvds connector is not damaged, then replacing the fuse is all that is required.

----------
astroboy907 said:
Took my late '08 15" logic board out tonight to do thermal paste and took some high def photos of the board (don't ask. My 2hr top case transplant ballooned into a 10 hr repair frenzy, ended up with me breaking my display glass and messing with a loose LDVS cable...). Didn't have anything but an old loupe to catch a photo of the fuse though. Message me if you need em and ill be happy to send them along. I can get pics of a mid 09 15 too in November (when it gets returned). Getting a mid 2010 a1278 from eBay and would be happy to get pics of that too. Shots are with a canon t2i so reasonable quality. My father has some high end optical stuff too, I'll see if I can get really good pics of the fuse and location. I'd be happy to help you get some of this information more organized. Maybe MR would let this have its own page, with better HTML design tools.
Click to expand...

Thanks. That would be great. I was thinking that it would be cleaner to start a new thread with just the fuse locations. We could point to that thread from the first post in this one. Then I could add fuse locations as I get a chance to document them.
 
Dadioh said:
That would be the fuse. The fuse blows when too much current flows due to a fault. If the fault was due to a liquid spill and cleaning the board removed the fault then you should be good. After removing the old fuse take a second to check the resistance measurement from the fuse output to a ground point. If it is a low number, say less than 100ohms, then you still have the problem and a new fuse would just blow again. In that case you would have some detective work to find the fault. But most of the time, if the spill is cleaned and if the lvds connector is not damaged, then replacing the fuse is all that is required.

----------



Thanks. That would be great. I was thinking that it would be cleaner to start a new thread with just the fuse locations. We could point to that thread from the first post in this one. Then I could add fuse locations as I get a chance to document them.
Click to expand...

hello dadioh thanks again for your help.. umm there was never a spill on this computer i think i may have burned the fuse by changing screens without taking out the battery but im not sure.the backlight was working fine on the damaged lcd then when i put the new screen in the display was working but backlight wasnt working all of a sudden. and when you say to check resistance from the fuse can you please be more descriptive of what you want me to try to do? should i put the new fuse in and then measure from the output? which side is the output? im pretty sure the battery has to be out before i go poking around trying to check for anything right? thanks again. and as far as buying the correct fuse.. can you verify this? 0402 2a 32v
 
Dadioh said:
I was thinking that it would be cleaner to start a new thread with just the fuse locations. We could point to that thread from the first post in this one. Then I could add fuse locations as I get a chance to document them.
Click to expand...

I have started a thread urging the creation of a dedicated Mac Repair sub-forum here. Let me know if you think it would be a decent idea for a home for this thread/issue as well as any others that may arise. I urge other users to chime in as well!
 
Backlight fuse for 2009 MBP

I ordered some 0204 2a fuses and hope to be able to replace my fuse.

I am posting some better pics in the hope that someone can verify that this is the fuse. Dadioh signified that it looked like it so I am almost sure.

Hope to see the repair forum open soon and will work on my photo taking as I will have some boards to post an would love to help as I have and am being helped.

The first pic is a number by the memory slot that appears to be a serial and ghz designation...??

Second pic is a perspective pic so you can see where it is and

Third is a close up of the OPEN 0204 package w/white dot on it

Anyone know this board and that it is the backlight fuse??

Thanks
 

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Hmm.. got my A1278 from eBay, looks so far like the board is in decent condition (slight water damage), but the fuse is blown, pin 8 or so of the LVDS looks like it's burnt/mangled but probably still connected. However the chip I assume to be the WLED driver looks like it's in bad shape. Two of the pins on the side pointing to the DVD drive look like copper (burned off pins?), so I assume I will have to replace the WLED, LVDS, and the fuse. Exciting :eek:

So, it looks to me like I am either going to have to sell as is, hire someone to fix, or do it myself. I went looking for hot air rework stations and found a few from $50 onwards on eBay. So, I don't know if you do hot air rework or not, but I think it would be a good investment (I am likely to be an EE major so I will probably do this for the rest of my life :D). I was wondering if you had any tips for a rework station, what type to get, with what kind of tips, etc. Would like to see around the $100 range, but am willing to look into better options. Looking to get at least 2 years out of it. A soldering iron attachment is not needed. Tweezer tips would be awesome but overkill. :D

Another thing- do you think I can do this with my inexperience? I hear horror stories sometimes about reworking... But with some solder paste and flux, I think I could (probably) do it. Would like to hear how difficult it is, if I could do it myself easily or not.. I have a couple of older motherboards around here, I could work a bit on them first. Anyways, take your time with an answer, you are pretty busy and I hate to bother you...
Thomas
Edit: added pic
 

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Last edited:
Early 2009 MBP 15" backlight fuse location

Problem resolved.

Anyone interested in this location it is confirmed.

Early 2009 MC026LL/A

Model with removable battery 2.66 ghz

Backlight restored by replacing this fuse.
 

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fuse location pics?

Is it possible to get the fuse location pics available from this forum group together on a page on N image server?

I have another one to fix now (mid 09 266ghz MacBookPro5,3) and the frustrating search begins all over again. IT SEEMS NO ONE HAS A COLLECTION OF THESE LOCATIONS!

Please correct me if I am wrong and if I am right may I help to build this resource?
 
midijamm said:
Is it possible to get the fuse location pics available from this forum group together on a page on N image server?

I have another one to fix now (mid 09 266ghz MacBookPro5,3) and the frustrating search begins all over again. IT SEEMS NO ONE HAS A COLLECTION OF THESE LOCATIONS!

Please correct me if I am wrong and if I am right may I help to build this resource?
Click to expand...

As of right now the collection is this forum. Dadioh has stated some interest in gathering all fuse locations to put on the main post (or just another thread, simpler).

I can't speak for him for what he wants but I am willing to offer my help gathering resources. Again, can't speak for him but I assume he is looking for hi-res shots of fuse locations. I'll be starting through the thread sometime this week gathering shots and positions for my personal use as well as to share with Dadioh.
 
Great info Thanks

cetchmoh said:
To give at least a little something back to the community, I compiled some information for the Macbook Pro 13" early (and late) 2011.

First things first. ID your board.
Look on your board for the serial number. It should read 820-2936-B (or something very close to this).
Look here:
[url=http://s22.postimg.org/7bsb66wel/board_big.jpg]Image[/url]

[url=http://s12.postimg.org/u1psllubt/bagrat_boardserial.jpg]Image[/url]

Frequently asked questions:
Where is the fuse?
Near the LVDS connector. A bit to the left, it should have a P on it.
[url=http://s7.postimg.org/shhma3n47/connector.jpg]Image[/url]

What kind of fuse is it?
3A, 32V, fast acting, 0603 package.
This is actually what the "P" tells you. See here: http://www.matronic.com/pdf/herstellerkataloge/littelfuse_katalog/Chapter10SurfaceMountFuses.pdf
Any fuse with this specs will work. If you want the fancy "P" on it, get one from "littlefuse".
There is something wrong with my LVDS connector (burned down pins, etc.), what kind of connector is it?
It's an I-PEX 20474-030e-11 (30 pins. Note the "030e"). Either search for this and get them cheap from asia, or search on ebay for "Macbook 2011 lvds connector" and pay more.
Where is the WED driver?
Look left from the Fuse. A tiny BGA package surrounded by resistors. See picture.
[url=http://s7.postimg.org/793xso8nb/wed_bga.jpg]Image[/url]

Where can I get one of these?
It's a relabeled Texas Instruments LP8550. Either order at least 500 of them from TI or, register as a company on their site and order some free samples. A third option would be ebay again. There are some sellers who offer them.
What do I need to do this myself?
If you need to ask this question, you should really consider to hire a professional to do this.
Where can I find schematics of my board.
Just google your board number and don't be lazy. There are a lot of shady websites who want to sell them to you. I would not recommend to buy from any of those. You can find a lot of russian, chinese, polish, etc forums where people post pdf schematics.
Click to expand...



Thanks for the info mine turned out to be the fuse to have no continuity

Now I have an issue with the power button and no funtioning keyboard

The 2011 MBP has a liquid spill. looks like an energy drink. Cleaned board... magsafe was dim green though would start with a force start via the power button and reconnecting the magsafe

took logic board back out .. reclean board and magsafe dc in board ..... got magsafe functioning.... my hint for a magsafe dc in board suffering a liquid spill and corrosion is to sock it and preferably use a ultrasonic cleaner.... worked a treat to get into the connections from the magsafe

Now that I have it fired up the keyboard and power button are not funtioning, nor is the forced smc start.... the backlight is still out on the lcd but that is the fuse by the looks.

any help with the power button and the keyboard would be appreciated as the power button was working and is not.... yes have checked all connections

Cheers

----------
Dadioh said:
Has anyone here used the solder rework station T862 for replacing BGA packages? I have quite a few boards that I believe the SMC is bad and wanted to be able to replace BGA packages. Sample listing below... there are lot's of them for sale on eBay from various sources for a little over $200.

Wanted to get first hand experience from someone that may have used one on their MacBook logic boards. Thanks.


http://www.ebay.ca/itm/PRO-T862-BGA...RDA-WELDER-SOLDERING-MACHINE-g1-/130620054775
Click to expand...


Hey Dadioh first up thanks for all your efforts and tech input

did you end up getting this?
 
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