MacBook Pro Unibody - No Backlight - Logic Board Question

[strikerba]

@Musicsoul78

yes, my MBP is connected to external monitor and this is what i get when i go to system preferences.

[cmdrdata]

Originally Posted by Musicsoul78

mr data is this the same 3a rated fuse??

http://uk.farnell.com/multicomp/mcse...-3a/dp/1841088

saves me using donor boards

many thanks

Looking at the spec sheet the fuse you shownis huge, L=6.1mm! I think the one in your logicboard is at most about 2 mm, but even then I am not so sure. I believe Dadioh mentioned most MBP fuses are package type 0402 or 0603.

[Musicsoul78]

Originally Posted by strikerba

@Musicsoul78

yes, my MBP is connected to external monitor and this is what i get when i go to system preferences.

Color LCD:
Resolution: 1280 x 800
Pixel Depth: 32-Bit Color (ARGB8888)
Mirror: On
Mirror Status: Hardware Mirror
Online: Yes
Built-In: Yes

its telling me that your video is being mirrored out to an external display.. thats why i asked,

what exactly are you trying to find out buddy?

----------

Originally Posted by cmdrdata

Looking at the spec sheet the fuse you shownis huge, L=6.1mm! I think the one in your logicboard is at most about 2 mm, but even then I am not so sure. I believe Dadioh mentioned most MBP fuses are package type 0402 or 0603.

think mine will be an 0603 fuse the one with a p on it...

thanks Data

[Musicsoul78]

mpb 13" 30 lvds pin out

notice the BKLT PWR/EN pins are always the ones that short or corrode as a result of water damage

always check these

[Dadioh]

Originally Posted by Musicsoul78

mpb 13" 30 lvds pin out

notice the BKLT PWR/EN pins are always the ones that short or corrode as a result of water damage

always check these

Good observation. The reason for this is that the backlight power pins are carrying 27V (full brightness). The process of electromigration is proportional to voltage so if you continue to run the logic board after the spill you will get accelerated corrosion on those pins with higher voltages.

Bottom line. If you have a spill always take the time to clean the logic board of all contaminants before attempting to power the Macbook. Some people think they got lucky because it is still working but the joy is short lived as the corrosion advances and destroys the board.

[Musicsoul78]

Originally Posted by Dadioh

Good observation. The reason for this is that the backlight power pins are carrying 27V (full brightness). The process of electromigration is proportional to voltage so if you continue to run the logic board after the spill you will get accelerated corrosion on those pins with higher voltages.

Bottom line. If you have a spill always take the time to clean the logic board of all contaminants before attempting to power the Macbook. Some people think they got lucky because it is still working but the joy is short lived as the corrosion advances and destroys the board.

how come the spill does not blow the fuse or the wled driver first???

and when it corrodes the pins it also corrodes the pads and traces it sits on, leaving it impossible for us to replace.

[Dadioh]

Originally Posted by Musicsoul78

how come the spill does not blow the fuse or the wled driver first???

and when it corrodes the pins it also corrodes the pads and traces it sits on, leaving it impossible for us to replace.

Depends on the spill. Some liquids conduct better than others. Pure water is actually a poor conductor. Add a few ions like salts however... And it is a great conductor. If the liquid can effectively conduct enough current to blow the fuse then it will.

The connector pins, solder pads, and traces are all carrying that voltage and so they will all corrode to a certain extent spending on their finishes.

[NicoNL]

No question about a backlight, but since it seems that most technical problems are solved in this thread I post this question here...

After I posted my first questions here a few months ago I repaired some 13 and 15 inch macbooks (mostly battery charge and backlight issues) but now I have this white 13 inch from 2007. A duo core. It looks like new, but unfortunately it keeps giving kernel panic, ie the grey screen of death "You need to restart your computer"

It is definitely a hardware problem.

What I did:
- using different and good memory modules
- trying both SIMM-slots apart
- booting from HD and from DVD
- try another DVD-player and another HD
- try with a harddisk from another Mac if I could log the kernel panic and show it on that other mac. No logs were made?
- check if OS 10.6 was compatible with a core duo. It is, but it says it need at least 1 GB. Since I tested with 512-modules, I retested with 1 GB modules. Still that message...

One strange thing: when powering up the screen flashes once (for 1/10 second) then, after a second or so it works normally.

Maybe (I hope) there are some people who have suggestions, about what can cause this error or how to find out so?

[Musicsoul78]

Originally Posted by NicoNL

No question about a backlight, but since it seems that most technical problems are solved in this thread I post this question here...

After I posted my first questions here a few months ago I repaired some 13 and 15 inch macbooks (mostly battery charge and backlight issues) but now I have this white 13 inch from 2007. A duo core. It looks like new, but unfortunately it keeps giving kernel panic, ie the grey screen of death "You need to restart your computer"

It is definitely a hardware problem.

What I did:
- using different and good memory modules
- trying both SIMM-slots apart
- booting from HD and from DVD
- try another DVD-player and another HD
- try with a harddisk from another Mac if I could log the kernel panic and show it on that other mac. No logs were made?
- check if OS 10.6 was compatible with a core duo. It is, but it says it need at least 1 GB. Since I tested with 512-modules, I retested with 1 GB modules. Still that message...

One strange thing: when powering up the screen flashes once (for 1/10 second) then, after a second or so it works normally.

Maybe (I hope) there are some people who have suggestions, about what can cause this error or how to find out so?

GPU are the main cause of kernel panics in most macs...
Remove the heat sink
Apply flux to the GPU and reflow that area
Search video on reflow
Then check if it still panics

----------

Originally Posted by Dadioh

Depends on the spill. Some liquids conduct better than others. Pure water is actually a poor conductor. Add a few ions like salts however... And it is a great conductor. If the liquid can effectively conduct enough current to blow the fuse then it will.

The connector pins, solder pads, and traces are all carrying that voltage and so they will all corrode to a certain extent spending on their finishes.

Ty dadioh

On the wled driver how can I test if its blown?

[abacomputers]

hello
i am new to this forum i am trying to fix a mac for a customer with no backlight coffee was spilled in but worked for about 12 hr after the spill

then backlight went out
every thing else seem to work just fine

taken logic board out and cleaned with 90% alcahol

but not sure how to test (or find) fuse or wLED cables seam to all be in good condition

now i am not the he greatest with electrionics but i do no how to use a mulit meter

so please any help would be great i would like to test wLED chip and fuse but if there is something else i should check let me know let me know if you need pic of other side

[healeydave]

There's a lot of discussion and previous examples like yours earlier in this thread!

I'd start by checking the component with the "p" on it (near the LVDS connector) for continuity.

[EricJ320]

Thanks to all those posting very useful information in this thread!

I have an A1286 Mid-2010 that took a spill of soda into the side. While it was sitting on it's end next to my bed, the baby kicked over a drink and it went into all the ports on the side of the computer. It was on at the time, and by the time I had gotten to it I feared the damage was done. I immediately turned it off, removed the power cord and turned it upside down and let it dry for a few days. When I powered it back on, holding my breath, it all worked but the backlight. Like so many others, it worked if you shined a flashlight from behind, and if you connected an external monitor.

After finding this thread I ordered a couple of tools I didn't have (Y driver and such), and dismantled the computer and gave the logic board a bath and scrubbing with a tooth brush in 99% IPA, as directed in this thread. My multimeter skills drop off dramatically after being able to test 12V DC, but I gave it a shot testing the suspect fuse in this thread. As best I could tell it was testing fine. So either I wasn't doing it right, or it was fine, and that probably meant the WLED driver was blown. I REALLY don't have the soldering skills to replace it. So I started looking for repair centers that could fix it, at a price I could afford. I figured I'd give it one last shot after having cleaned the board, and VIOLA!, it worked!

I am completely confused why just cleaning the board seemed to fix the problem. My question, now that the board is clean, am I in the clear, or am I just living on borrowed time? Is it likely the problem will resurface later, and/or go out completely?

The first picture below was before I cleaned the board, the second was after the cleaning and I circled what I believed to be the 0402 fuse.

Again, thanks to all in this thread, especially Dadioh, for helping me out in what seemed an impossible task for someone like me!

[abacomputers]

Originally Posted by healeydave

There's a lot of discussion and previous examples like yours earlier in this thread!

I'd start by checking the component with the "p" on it (near the LVDS connector) for continuity.

i do not have continuity . that what i thought the fuse was . i checked both side to make sure i do not have a short to ground and i do not the voltage on 1 side is 12.5 and 0 the other
but if i turn off mac and bridge the fuse ,when i turn back on the mac starts then shuts down agian with no image on lcd
with out it bridge it turns on with image on screen but no back light

do i have to reset the smc after bridgeing or something else
where is the wLed chip and how do i test it

thank you

[gene510ss]

My issue is that my backlight works only when I boot from a cold start up. When when it is warm and I close the lid, open it back later no backlight. I cant adjust it meaning the brightness through the F1 or F2 or in preferences nothing happens stays the same. When its working the brightness thing comes up on the screen like im adjusting it but no dimming or brighting. So when my macbook has been on awhile if closed the back light goes out completely What could this be? any help please, Thank you!

[fixitya]

Hi Dadioh,

I have read several of your suggestions here and very impressed that you are providing a helping hand to resolve our macbook problems. I would like to thank from the bottom of my heart to you and others providing help for all your contributions here. I couldnt believe earlier there can be such a thread for these component level discussions but only found this just a few days back.

I have got the same known backlight issue with 13" Macbook Pro 2.26. I received a machine with no capacitor (white one high frequency) as someone already tried on this logic board. Just to be on the safer side I have already replaced the WLED driver yesterday but after powering up there is still no backlight.. Most probably this is because this capacitor is missing? I dont know the value of this capacitor which if you could please suggest and where can I buy one? Any link for the part no. would be highly appreciated..

Thanks.

[abacomputers]

hello i have a mac book pro A1278 that has not backlight after water spill .the rest of the computer seem to work fine .

can some one help me find and test the wled driver .

i beleave i have found the fuse ( bad) and have tested both side to make sure i do not have a short to ground . but when i bridge the fuse the mbp no longer boots ( it starts run for about 2 sec. then turns off . with the fuse unbridged it boots and works but no backlight .

i am including pic of the board the circle is what i belive the fuse is
but i need help finding and testing wled and booster diode any help

[Dadioh]

Originally Posted by EricJ320

The first picture below was before I cleaned the board, the second was after the cleaning and I circled what I believed to be the 0402 fuse.

Again, thanks to all in this thread, especially Dadioh, for helping me out in what seemed an impossible task for someone like me!

Good job. The liquid must not have blown the fuse since a fuse would not recover after cleaning. There must have been residue from the liquid that was providing a path for leakage current which was preventing the backlight from working. Cleaning the residue seems to have solved this.

As long as the cleaning was thorough it has stopped any corrosion from further damage. The fact that you cleaned it quickly is a good thing. You are probably ok now but you can never completely rule out future related issues.

----------

Originally Posted by abacomputers

i do not have continuity . that what i thought the fuse was . i checked both side to make sure i do not have a short to ground and i do not the voltage on 1 side is 12.5 and 0 the other
but if i turn off mac and bridge the fuse ,when i turn back on the mac starts then shuts down agian with no image on lcd
with out it bridge it turns on with image on screen but no back light

do i have to reset the smc after bridgeing or something else
where is the wLed chip and how do i test it

thank you

Your fuse is blown. With power ON you should measure 12.5V on both sides. Bridging the fuse is a very dangerous thing to do. The fault that caused the fuse to blow is still there as evidenced by your MacBook shutting itself down to save itself. You need to determine what fault exists on the downstream side of the fuse causing the issue. Power off the machine and disconnect battery. Start by measuring resistance from the backlight pins on the lvds connector to ground. I suspect you might have a short there.

In your first picture the WLED driver is the square package just up and to the right of the fuse. It is a BGA package so you can only measure by the components next to the device.



----------

Originally Posted by gene510ss

My issue is that my backlight works only when I boot from a cold start up. When when it is warm and I close the lid, open it back later no backlight. I cant adjust it meaning the brightness through the F1 or F2 or in preferences nothing happens stays the same. When its working the brightness thing comes up on the screen like im adjusting it but no dimming or brighting. So when my macbook has been on awhile if closed the back light goes out completely What could this be? any help please, Thank you!

Very odd behaviour. Sounds like the backlight circuit has a bad solder joint somewhere. When the MacBook heats up there is some relative movement of components due to different expansion rates under heating and cooling. Does the backlight adjustment work when it is cold?

My best guess is that the WLED driver needs to be replaced. Tricky job on the 2011 model since it is a ball grid array (BGA) package.

[abacomputers]

"Start by measuring resistance from the backlight pins on the lvds connector to ground. I suspect you might have a short there" thank for the reply


dose any one know what pins on the lvd is backlight and what they should be getting for resitenes reading to ground

thank you for everyone that has responded to help me with this no backlight issue

[Musicsoul78]

Originally Posted by Musicsoul78

mpb 13" 30 lvds pin out

notice the BKLT PWR/EN pins are always the ones that short or corrode as a result of water damage

always check these

Originally Posted by abacomputers

"Start by measuring resistance from the backlight pins on the lvds connector to ground. I suspect you might have a short there" thank for the reply


dose any one know what pins on the lvd is backlight and what they should be getting for resitenes reading to ground



thank you for everyone that has responded to help me with this no backlight issue

check my previous post for the pin out!!!

[Musicsoul78]

MacBook Pro 13.3 Core i5 Laptop MC700 (Feb 2011) No Backlight

fuse good
lvds good
wled Replaced

now what ?????

here are some pics

Thanks to you all who contribute.

[Musicsoul78]

Originally Posted by fixitya

Hi Dadioh,

I have read several of your suggestions here and very impressed that you are providing a helping hand to resolve our macbook problems. I would like to thank from the bottom of my heart to you and others providing help for all your contributions here. I couldnt believe earlier there can be such a thread for these component level discussions but only found this just a few days back.

I have got the same known backlight issue with 13" Macbook Pro 2.26. I received a machine with no capacitor (white one high frequency) as someone already tried on this logic board. Just to be on the safer side I have already replaced the WLED driver yesterday but after powering up there is still no backlight.. Most probably this is because this capacitor is missing? I dont know the value of this capacitor which if you could please suggest and where can I buy one? Any link for the part no. would be highly appreciated..

Thanks.

think the part your looking for is this!!
http://uk.farnell.com/jsp/search/pro...sp?SKU=1843812

big white A6 fuse

[fixitya]

Originally Posted by Musicsoul78

think the part your looking for is this!!
http://uk.farnell.com/jsp/search/pro...sp?SKU=1843812

big white A6 fuse

Thanks for that. But I dont think this is a fuse, its for sure a capacitor. One end is ground I have traced it all along. If you have a similar board then please can you check and double confirm this for me? Thanks for your help.

[Musicsoul78]

Originally Posted by fixitya

Thanks for that. But I dont think this is a fuse, its for sure a capacitor. One end is ground I have traced it all along. If you have a similar board then please can you check and double confirm this for me? Thanks for your help.

your description is too vague ,,,,
i need visual guidance as to which component your searching for...


pics please

[fixitya]

Originally Posted by Musicsoul78

your description is too vague ,,,,
i need visual guidance as to which component your searching for...


pics please

Please check the image attached. This is the part I am talking about.

Thanks

[Musicsoul78]

Yeah it's the same as the one I sent you kn the link...
I've replaced about 45 now on different boards.

You can double check with dadioh and Cmrdata
But it's defo that fuse for sure.

Same on all boards there are 3 on there
2009 -2010

However different on 2008 and 2011 - 2012
No upper white fuse near lvds

Only near dc- in And battery dock connector