MacBook Pro Unibody - No Backlight - Logic Board Question

[greekhero]

Soldering LP8550

nah its tiny, plus most of the time these BGA's fail theres no going back, unlike a standard chip that would fail over time due to bad solder, these usually go bad due to liquid or other damage that would render the chip completely useless.

you can buy new chips and there DIRT cheap they come with solder balls attached, then its just a case of
removing the old chip
very carefully cleaning the pads
attempting to align the new cheap
and of course re soldering it. they tend to drop into place youl know when its reflown.

My only caution is if your not good at soldering maybe dont go over the pads with wick, pads under this bga aswell as under the smc chip are fairly delicate, more likely than pulling one you'll scratch mask away from a trace and its usually no problem.

----------

Hi ZZZAC,

I checked with TI and you are right, they say the LP8550 comes pre-balled. My question is: do I need to apply and solder on the pads before trying to solder the new chip? or I simply need to:

1. Remove the chip.
2. Clean the pads
3. Apply flux on the pads
4. Align the chip on the pads
5. Reflow the chip?

Here is the picture of the pins on the board that I have after removing the chip. The original chip was actually ok and the short was actually on the LVDS connector I also read that the chips you buy from the market are not programmed for dithering so they are not as good as the original chip. Do you know a way to program the chip? I see the SDA, SLC and GND lines, so one wire is possible but I am not sure how I can facilitate that.

Thanks!

 

[phong88]

The purpose of the two resistors on the enable pin of the WLED chip is to divide the voltage from 12v to 3v so to enable the output of the WLED
If either of these resistors have failed it wont enable the wled thus not enabling the backlight.

Check the resistance of the two resistors on the WLED enable line, one of them may be open. its best to remove them to test them, i have had some confusion with false readings on the resistors (mainly the 330k resistor)

Basically if you have no 3v to the wled one of those resistors has probabley failed. if you replace them and see no change id suspect the wled itself. (recently had a MBA where the wled being bad would cause the enable resistors to nly read about 20k, replacing the horrid bga wled resolved it)

Thanks ZZZAC. Do you have a picture of the location of the 2 voltage divider resistors on the mid 2010 15" MBP? I think the 330k is one of them, I'm not sure where the other one is.

 

[allisonfranz]

depends on your equipment. i used a 60€ hot air station. there's a guide by dadioh somewhere in this thread, since i also had no clue of hot air soldering back then.
but the process itself is kinda easy, since the driver is very small. just thorougly put kapton tape around the chip, so you are not going to blow away any other pieces.
heat it up, take it off, clean the pads on the board, apply some flux and reapply the new driver. takes about 20 minutes.

for desoldering you could possibly just put a big blob of solder on top of the old chip and heat it with a soldering iron. since the chip is so small that could work. but you'll need a hot air station for resoldering anyway.

 

[lopez224]

Macbook Pro 13" A1278 no backlight issue

Hi, Im new to this furum and I need help to identified the components on my logic board that I need to replace.

 

[lopez224]

Macbook pro 13"A1278 no backlight issue

Please help me to identified the 5 compoentns on my logic board and if you can guide me were to buy them would be great.
Thanks.

 

[shane.e.evans]

what chip is this?

Hi everyone,

I've been searching and cannot find out what this chip is on my 2009 macbook pro 13" logic board. it is located just next to the power supply input.

The chip says "7149 $AT^ W06C" (^ is a delta triangle and the $ is some messed up S with a diagonal slash through it.)

Does anyone know what it is and where I can get a new one? I received the machine with water damage and some of the pins are completely missing and have no metal exposed. Ha

Thank you so much!
Shane

 

[macrepair]

I'm fairly certain this is the WLED driver - have found that pin 24 on the QFN package is connected to LVDS backlight pins and is outputting only just over 8V but should I believe should be around 40V .

I have no idea who manufactures this chip or where I can source a replacement.

Also not sure why this has failed as don't believe this has had any liquid spillage in the past.

Hope someone can help!

I have replaced the WLED driver twice now and the LVDS connector and fuse but there is still a problem.

When I turn the laptop on the backlight comes on for a split second then goes off again.

I have also tested with another screen but same fault. Hopefully it's something simple but not sure what to test next.

Does anyone have any ides what could be causing this or had a similar fault? Any help or suggestions will be really appreciated!

 

[macrepair]

The purpose of the two resistors on the enable pin of the WLED chip is to divide the voltage from 12v to 3v so to enable the output of the WLED
If either of these resistors have failed it wont enable the wled thus not enabling the backlight.

Check the resistance of the two resistors on the WLED enable line, one of them may be open. its best to remove them to test them, i have had some confusion with false readings on the resistors (mainly the 330k resistor)

Basically if you have no 3v to the wled one of those resistors has probabley failed. if you replace them and see no change id suspect the wled itself. (recently had a MBA where the wled being bad would cause the enable resistors to nly read about 20k, replacing the horrid bga wled resolved it)

----------



nah its tiny, plus most of the time these BGA's fail theres no going back, unlike a standard chip that would fail over time due to bad solder, these usually go bad due to liquid or other damage that would render the chip completely useless.

you can buy new chips and there DIRT cheap they come with solder balls attached, then its just a case of
removing the old chip
very carefully cleaning the pads
attempting to align the new cheap
and of course re soldering it. they tend to drop into place youl know when its reflown.

My only caution is if your not good at soldering maybe dont go over the pads with wick, pads under this bga aswell as under the smc chip are fairly delicate, more likely than pulling one you'll scratch mask away from a trace and its usually no problem.

----------



Few things to check.
Do you get voltage across the diode? (this rules out the power enable fets that come just after the fuse)

Have you checked two resistors, they go to the enable pin of the wled, if either resistor is open the wled chip wont be enabled.

Sorry seem to have missed your post.. thanks for your reply!

Can you please let me know what diode and resistors I should check?

This is from the LED driver data sheet (http://www.freescale.com/files/analog/doc/data_sheet/MC34845.pdf?&Parent_nodeId=&Parent_pageType=)

 

[macrepair]

I have replaced the WLED driver twice now and the LVDS connector and fuse but there is still a problem.

When I turn the laptop on the backlight comes on for a split second then goes off again.

I have also tested with another screen but same fault. Hopefully it's something simple but not sure what to test next.

Does anyone have any ides what could be causing this or had a similar fault? Any help or suggestions will be really appreciated!

Forgot to mention after replacing the WLED driver the backlight came on for about 30 seconds before turning off.

Now there is no voltage on Vin or Enable pin on WLED driver but there is 8.4V on the fuse.

Also what is this part .638Z? There is 8.4V on the one side which is connected to fuse and other side shows 0V.

 

[aerique]

Hi,

I have got an A1466 Macbook Air that has had a liquid spill. It does not have any no visibly blown components. Also no spilling close to LVDS connector. After cleaning it with pure isopropyl alcohol it does not want to start, the magsafe led does turn on orange. No fan or screen action.

The keyboard is not clean, so likely that will cause it to not be able to turn on. Is there a trick to turn it on without the keyboard plugged in ?

 

[Ilwakeboarder87]

No backlight :-(

Hey Y'all,

First off thanks for the great forum and knowledge you guys have here. I've been learning and gaining answers from you guys for awhile now. Now I have a problem that I cannot seem to find the answer to within this thread. (Though having to admit, I did not read every page as I found something different within my system)

That being said, here is the issue.

Early 2011 A1286 15" 2.0ghz i7
Motherboard: 820-2915-A

The backlight on it is not currently working. I was able to see the image by putting a flashlight to the apple logo on the monitor. It showed through and the desktop could be seen.

Came to this thread to find out how and what component to repair but found what looks like a scratch from a screwdriver and two components completely missing off the board.

Can someone please help me to identify what these two components are and if you believe that it's part of the reason for no backlight.

I've attached an image. Red is what's in question, Yellow is where the components are missing (just below the color) and the blue it looks a little weird to me there, like something was spilled.

If you guys could please provide some guidance it would be much appreciated.

 

[lapcservices]

no power

hi
anyone know where i can get part number for this power chip 148av a2014 fsa.
or where i can buy it.
Thank you

 

[TiberioG]

I have a lcd assembly of a early 2011 17" mbp with a lp171wu6-tlb2 panel and I would like to trasform it in a external display. I have bought a lvds controller suitable for the led display but it has a male interface that should be connected into the rear connector of the panel: this means that i should remove the glass and disassemble the lcd assembly.

I would like to manually connect the wires showed in photo to the lvds controller but i don't know the exact pinout, better, i know the 40pin ipex pinout but why there are connected only 24 wires?

 

[toketo]

mbp 13" core i7 early 2011.

hi, I'm fighting with a 13 mbp early 2011, the backlight does not turn as you change the driver wled and fuse but still not turn, anyone who can help? Thank you.

 

[mvmanolov]

Does anyone have the board view file for 820-3115-A
Its a mid 2012 MBP 2.5 i5.


Thank you and much appreciated!

 

[bigfoot53]

A1342 Help

For all Polycarbonate Macbook A1342 owners: I have marked the Fuse and the LED Driver on the following images.
http://imageshack.us/photo/my-images/839/fuses.jpg/
http://imageshack.us/photo/my-images/189/leddriver.jpg/
The LED Driver has the following printed on it:
MC34834
4GROAJ
Its Datasheet can be obtained here:
http://www.freescale.com/files/analog/doc/data_sheet/MC34845.pdf
my only problem is that there are 10 variants on digikey:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=2556628&k=mc34845
They differ in their Frequency. Does anybody here know how I can determine the desired frequency for my a1342 Macbook?

Hello Everyone,
I have a question about my A1342 I believe that I have a fuse issue but can someone guide me in the right direction to fix it?
the original issue was the display would get line through it and then black out if I moved the display slightly it would come back on and work for a while. so I thought that the cable might be loose so I checked the cable on the motherboard and it was fine then opened the display and checked the cable and it was fine but while I had the bevel off the display and was checking the operation I saw a brief flash / spark form the cable / connecter and then the backlight went out. I have replaced the display and all cables with one form a working machine but the backlight still doesn't work. I have checked the voltage on the fuse form the pics and I have 11.71 volts on one side and 4.50 on the other side. Is the fuse bad? or could something else be bad from the spark. "I really believe that the original cable was bad and caused the spark/short"
Any and all help is greatly appreciated.


Thanks
Bruce

 

[emin94h]

Hey guys.

I accidentally spilled some water on my Macbook Pro, when I turned on the Mac a few days later the backlight suddenly stopped working.

I have a early 2011 Macbook Pro 15,4" with a 820-2915-B logic board, I red that the backlight fuse is the main cause of the problem so I bought a multimeter to check the fuse for continuity. Since I'm new to using a multimeter device I don't know what readings I should get if the fuse is blown, therefore tested them all so maybe you could see if the fuse is OK/blown, this is what I got:
At 20Ω = 1
At 2000Ω = 1297 before it instantly dropped to 1
At 20kΩ = 10,99 for a couple of sec then back to 1
At 200kΩ = 155,0 and increasing
At 20MΩ = 3,45 and from here it decreases really slow...
I'm pretty sure it's already blown but doesn't hurt asking some professionals.

Now to the other problem, I don't which size of the SMD fuse I should buy, at macrumors a lot of people says 0402 and some says 0603, pretty confusing.
I uploaded a picture for you to see, it's the fuse with a "P" on it.
Hope this information was to any good.

 

[Dadioh]

Hey guys.

I accidentally spilled some water on my Macbook Pro, when I turned on the Mac a few days later the backlight suddenly stopped working.

I have a early 2011 Macbook Pro 15,4" with a 820-2915-B logic board, I red that the backlight fuse is the main cause of the problem so I bought a multimeter to check the fuse for continuity. Since I'm new to using a multimeter device I don't know what readings I should get if the fuse is blown, therefore tested them all so maybe you could see if the fuse is OK/blown, this is what I got:
At 20Ω = 1
At 2000Ω = 1297 before it instantly dropped to 1
At 20kΩ = 10,99 for a couple of sec then back to 1
At 200kΩ = 155,0 and increasing
At 20MΩ = 3,45 and from here it decreases really slow...
I'm pretty sure it's already blown but doesn't hurt asking some professionals.

Now to the other problem, I don't which size of the SMD fuse I should buy, at macrumors a lot of people says 0402 and some says 0603, pretty confusing.
I uploaded a picture for you to see, it's the fuse with a "P" on it.
Hope this information was to any good.

Fuse is blown. If it was good then on the 20 ohm scale you would read 1 or 2 ohms depending on the quality of your test leads. Ideally it is 0 ohms but touch your two test leads together on 20 ohm scale and that is the minimum you can read. I assume on your meter that the "1" is left justified so it indicates over range.

The fuse is an 0603 size and should be rated at 3 Amps.

 

[emin94h]

Fuse is blown. If it was good then on the 20 ohm scale you would read 1 or 2 ohms depending on the quality of your test leads. Ideally it is 0 ohms but touch your two test leads together on 20 ohm scale and that is the minimum you can read. I assume on your meter that the "1" is left justified so it indicates over range.

The fuse is an 0603 size and should be rated at 3 Amps.

Thanks for the quick reply Dadioh, was actually about to send you a PM but wanted to try post it here first. Yeah assumed it was blown, since Mega Ohm readings indicates that the fuse is blown.
I order as late as yesterday that fuse, think this one will work even though they're not the same color?

http://www.ebay.com/itm/10-Pcs-Litt...217?pt=LH_DefaultDomain_0&hash=item2a2544c4a9

 

[Dadioh]

Thanks for the quick reply Dadioh, was actually about to send you a PM but wanted to try post it here first. Yeah assumed it was blown, since Mega Ohm readings indicates that the fuse is blown.
I order as late as yesterday that fuse, think this one will work even though they're not the same color?

http://www.ebay.com/itm/10-Pcs-Litt...217?pt=LH_DefaultDomain_0&hash=item2a2544c4a9

Those are exactly the right fuse characteristics. Different manufacturers use different colors. The "P" indicates 3A I believe. These will work.

----------

Hello Everyone,
I have a question about my A1342 I believe that I have a fuse issue but can someone guide me in the right direction to fix it?
the original issue was the display would get line through it and then black out if I moved the display slightly it would come back on and work for a while. so I thought that the cable might be loose so I checked the cable on the motherboard and it was fine then opened the display and checked the cable and it was fine but while I had the bevel off the display and was checking the operation I saw a brief flash / spark form the cable / connecter and then the backlight went out. I have replaced the display and all cables with one form a working machine but the backlight still doesn't work. I have checked the voltage on the fuse form the pics and I have 11.71 volts on one side and 4.50 on the other side. Is the fuse bad? or could something else be bad from the spark. "I really believe that the original cable was bad and caused the spark/short"
Any and all help is greatly appreciated.


Thanks
Bruce

A fuse is basically Zero ohms so you should see the same voltage on both sides. The 11.7V seems kind of low. Is this running off battery and that is almost dead? The 4.5V doesn't make much sense unless it is back feeding from the backlight driver. When a fuse blows it goes to Megaohms which means it should be 0 Volts on the other side.

----------

hi, I'm fighting with a 13 mbp early 2011, the backlight does not turn as you change the driver wled and fuse but still not turn, anyone who can help? Thank you.

The backlight driver on that is an LP8550 which is a 25 pin BGA package. Are you certain it is soldered correctly? What method did you use?

----------

I have a lcd assembly of a early 2011 17" mbp with a lp171wu6-tlb2 panel and I would like to trasform it in a external display. I have bought a lvds controller suitable for the led display but it has a male interface that should be connected into the rear connector of the panel: this means that i should remove the glass and disassemble the lcd assembly.

I would like to manually connect the wires showed in photo to the lvds controller but i don't know the exact pinout, better, i know the 40pin ipex pinout but why there are connected only 24 wires?

There are a lot of grounds in the pinout. Some of your wires are likely coax which means an outer ground and internal signal.

I applaud the enthusiasm but seems like a lot of work to get an external 17" display.

 

[Broken.Mac]

Another Water Damaged MacBook Pro

Hi All

Thought I might try my luck and see if anybody could give me a hand..

I was lucky enough to be given an a1278 which had had coffee spilt on it. I thought I would see if I could get it working again. Was told that the repair cost would be in excess of $500 including new top/keyboard and battery.

After lots of reading, I disassembled the unit and cleaned up as much as I could with 99.7% alcohol - there was a few areas of the logic board which had some dried coffee on it! I also got a new battery and checked the magsafe connector.

After the cleanup, and a second hand battery test connector which I didn't see when disassembling the logic board, I plugged in the power and crossed my fingers... to my surprise, the power adapter was glowing green, it then booted up and got to the desktop , was I happy person!! I tested all the keys on the keyboard and mouse and those too were working...

I then noticed a few things.
1. The battery was not being detected by the operating system. The system said that there was no battery installed.
2. The power button doesn't work - the only way the system will shut down is to use the software option. I can hold the button down for 30 seconds with no effect. Once the system is shutdown, there is no way to restart the machine short of taking the cover off and disconnecting the battery.

One thing I have found is that this site is a goldmine of info - I think I might have solved the power switch solution (and cheap as well). I have found a cheap keyboard on Aliexpress (http://www.aliexpress.com/item/For-13-Unibody-Macbook-Pro-A1278-Keyboard-US-Layout/723150764.html) but wasn't sure if it was the correct one so if someone could take a look and let me know.

As for the battery charging problem, I have no idea - would that be a logic board problem or is it is a magsafe connector problem. I have attached both back and front pictures of the logic board so any pointers on where to start would be fanstastic.

FRONT

BACK

I also realised that the secondhand battery tester (long ribbon connnect to the side of the machine) was second hand for a reason - it was half cut near the logic board connector - would this cause the unit not to detect the battery?

So, sorry for the long winded post but thought that I had better post more information than less I know that I would need to get the new keyboard and install it but not sure what to do about the battery?

Thanks again in advance..

 

[dieett]

A1226 Board view 820-2101, & viewer

Hello everybody!!

I have a 820-2101A board, used to work fine, but now I have no image on lcd (INVERTER VERSION), I do have video on external when ldvs is disconnected. I've measured 12v on the backlight connector and inverter is good, tested with 2 other working lcd screens so the issue is not the inverter nor the cable or lcd screen. I do have the schematics but i dont have the board view so its getting hard to find the components. Do you guys think it has to do with the u9560?? any suggestions please??? thanks in advance!!!

see here:
http://www.4shared.com/postDownload/Mb3Q0zAb/M57 DVT MLB.html#

greetings

 

[phong88]

No enable voltage

Hi, I have a 15" 2010 mbp that doesn't have backlight. It seems there is no enable voltage on the L8545SQ chip. From this forum it seems there should be a voltage divider that feeds the enable pin. Does anyone know where are those resistors are? I can't seem to locate them.

Thanks.

 

[pedroxoliveira]

Componente 74 with 0 Volts

Hi, I have a 15" 2010 mbp that doesn't have backlight. It seems there is no enable voltage on the L8545SQ chip. From this forum it seems there should be a voltage divider that feeds the enable pin. Does anyone know where are those resistors are? I can't seem to locate them.

Thanks.

Hi, there before anything macrumors is just great ...

I have a mac A1278 - 820-2565A, no backlight issue, the fuse is ok, IC LP8545 impedance for all pins is similar about 0,5K for each pin, and the volt in pin 21 and 22 is about 5V, however volts in component 74 is 0V, how this is possible if I have volts in pin 21 and 22.

maybe some one could help me with this

Best regards

PO

 

[A Hobo]

BAcklight fuse locations

Hi guys, I'm not sure if these have posted before but i have the whole collection of fuse locations incase they help anyone out.

wish there wasn't a 5 file limit..