MacBook Pro Unibody - No Backlight - Logic Board Question

[dfh88]

I haven't seen the pin out posted for the 15". I had another go yesterday, replaced the 2A fuse but no joy still no backlight. I was thinking of connecting an external supple of 18-27V to pins 38-40 to see if the led's war at least working. this way i could figure out if it is logic board side or screen side.

any thoughts?

i think someone posted earlier in the thread they managed to power up the leds this way. do you have the 27v on the motherboard? here is the pinout:

https://forums.macrumors.com/attachment.php?attachmentid=316064&d=1323870576

it may be possible to build a add on wled driver if all else fails?
this could possibly do the job if you could find out how to connect it

http://www.ebay.co.uk/itm/NATIONAL-...-2-IC-WLED-DRIVER-POWERWISE-LLP-/260877659350

 

[PJonHar]

Thanks for the info

 

[Dadioh]

success! the green things are additional fuses.
for now i replaced it with a 1a glass fuse with leads soldered on, taped next to the fan.


so mine blew due to the clip that holds the screen cable shorting on the back of the connector, the new one came better insulated:


Dadioh thanks for your help, another macbook saved

Congratulations

Just a quick note though. The green devices are not fuses. They are precision resistors that the WLED driver uses to figure out how much current it is pumping into the LED's. I guess if it is working with the 1A fuse then the resistance of the glass fuse is "close enough". But if it is working then... hey... who am I to argue

Merry Christmas. Enjoy your backlight....

----------

Hey Dadioh, here is a better pic of the burn in fuse area

Image

I took it to a technician with replacement fuse, but I am having a feeling the motherboard is beyond repair. They are supposed to be multi-layered, so it is very possible that it burned internal items.

What do you think? Tech said he will try to "fill" the hole and place the new fuse.

Yikes. Looks like the fuse really didn't do its job They are supposed to gracefully go open circuit.

You are right. these boards are multiple layers like a lasagne so if it managed to burn through to the lower layer there could be issues. But what have you got to lose? Give it a try.

----------

I have the schematics for the logic board side. Is it possible to get the Screen side schematics?

Also,

@ dfh88 how easy was it to remove your screen? did the glass come off okay?

As far as removing glass goes... I learned by the school of cracked glass... do not follow the video guides that show you starting in the top corner and tugging with a suction cup. Rather, start in the bottom right corner. Heat the glass around the corner and then use a plastic pry tool (I use one from iFixit that is used for iPhone repairs). Lift very very very carefully and if you have a suction cup (also at iFixit) then use that to pull gently. Once you have a bit of clearance work a plastic card into the gap (old credit card is OK but a little thick). Then work your way around the screen heating as you go. Careful around the camera. Suction cups are then really useful to lift it away.

Takes practice and lot's of patience but I am finally at the stage where I can do it 99% of the time.

 

[Dadioh]

I haven't seen the pin out posted for the 15". I had another go yesterday, replaced the 2A fuse but no joy still no backlight. I was thinking of connecting an external supple of 18-27V to pins 38-40 to see if the led's war at least working. this way i could figure out if it is logic board side or screen side.

any thoughts?

Here is the 15" pinout.

 

[PJonHar]

Thanks. Hopefully it won't come to removing the glass. I'm going to try another fuse now.

Just wondering how is everyone measuring the voltage of the wled pins when the logic board is installed, it's not the side you can get too?

 

[Dadioh]

Thanks. Hopefully it won't come to removing the glass. I'm going to try another fuse now.

Just wondering how is everyone measuring the voltage of the wled pins when the logic board is installed, it's not the side you can get too?

On the MBP 13" they are on the top side. On the MB Aluminum Unibody they are on the bottom.

When they are on the bottom I measure right at the pins of the LVDS connector. But I have very fine tip probes. I would not try that with large clunky probes.

 

[PJonHar]

AArghh. Still nothing, replaced the fuse with a piece of F rated 2A fuse wire but nothing. the fuse wire is still okay but i was only getting around 1V on pins 38,39 & 40. Suspecting the WLED driver is at fault or the booster circuit?

 

[dfh88]

AArghh. Still nothing, replaced the fuse with a piece of F rated 2A fuse wire but nothing. the fuse wire is still okay but i was only getting around 1V on pins 38,39 & 40. Suspecting the WLED driver is at fault or the booster circuit?

i got about 1v when the resistor was blown, changing the brightness level made a slight difference to the voltage also. did you check the cable and connector for shorts? with my old cable plugged in 39 & 40 were shorted to earth inside the connector.

you could try an external supply voltage to 39 and 40, remove the two caps maybe and connect it there. it risks doing more damage though. i don't know if the led return 1-6 would still carry the return current. psu voltage, 18.5v, should enough to get it to light up, with a small fuse eg 1a glass fuse in circuit for protection. it may be nescesarry to route the led return to earth also, maybe unsolder the resistors near the weld driver. of course its much better to get it working properly if you can, but if all else fails.

there are small voltage step up converters with adjustable output voltage, too big to go in the case but it could stick it on the lid in a box to get it usable again, or maybe take the optical drive out.


http://www.ebay.co.uk/itm/LM2577-DC-DC-Adjustable-Step-up-Power-Converter-Module-/280734840807

it could take power via the usb 5v or off the battery/12v supply inside.

 

[dfh88]

Congratulations

Just a quick note though. The green devices are not fuses. They are precision resistors that the WLED driver uses to figure out how much current it is pumping into the LED's. I guess if it is working with the 1A fuse then the resistance of the glass fuse is "close enough". But if it is working then... hey... who am I to argue

i thought they might be for this, 'shunt resistor'?

i want to change it for a resistor. do you think this is close enough:

http://www.ebay.co.uk/itm/Metal-Film-Resistor-1-8W-1-6W-0-1-Ohm-1-100-pcs-/220698331832

i know its not surface mount but much easier to solder in.

 

[Dadioh]

i thought they might be for this, 'shunt resistor'?

i want to change it for a resistor. do you think this is close enough:

http://www.ebay.co.uk/itm/Metal-Film-Resistor-1-8W-1-6W-0-1-Ohm-1-100-pcs-/220698331832

i know its not surface mount but much easier to solder in.

The schematic shows 2 X 0.4ohm 1% resistors. So that would make them 0.2ohms in parallel. If you can get a 0.2ohm 1% that would be about right. Never really considered putting through hole components on surface mount pads. There will be quite a strain on the solder pad so you need some good strain relief if you go this route. Obviously it would be better if you used SMT resistors but work with what you've got.

Good Luck

 

[dfh88]

The schematic shows 2 X 0.4ohm 1% resistors. So that would make them 0.2ohms in parallel. If you can get a 0.2ohm 1% that would be about right. Never really considered putting through hole components on surface mount pads. There will be quite a strain on the solder pad so you need some good strain relief if you go this route. Obviously it would be better if you used SMT resistors but work with what you've got.

Good Luck

in the area where i soldered there is plenty of space, one side is on the edge of the square transformer thing, the other one has a dot next to where the resitor goes, but is on a big track. i could get a surface mount one though.

is is not R9730 shown here?

the two in parallel must be the pair next to each other in my pic ??

 

[naKruul]

MB Pro Early 2011

Hi Guys,

I'm having some issues with the backlight of my early2011 13" MB Pro i5 after a Coke shower...
Thing is following:
Everything cleaned thoroughly and got a new keyboard. The Macbook powers on just fine and works flawless. But after some time the backlight starts to flicker. When you try to dim the backlight in this state it will switch off completely. Setting a higher brightness works but the display will eventually start to flicker again. You can continue like this to the highest brightness but the backlight will eventually shutdown completely. No getting it back to work in this state. If you switch the computer off and let it sit for like 3-4 hours it will power on just fine with backlight working again(even dimming to lowest level). But after some time it's going to fail again.

Any suggestions?
Thanks in advance

 

[AmTx]

Hello guys,
My friends has Macbook A1278. He had spoiled coke on it. I cleaned it carefully,image is visible,but backlight isn`t working.I`m new to electronics,but I figured out that A2 0402 fuse isn`t open (I don`t know how to say it right in english,but multimeter in beep mode doesn`t beep ). When I connected a with wire it both sides backlight appeared for a moment,then protection worked. And I detected that lcd connector has a burned pin,it was damaged before. So what I need to do?
Buy new cable and fuse? How to check l8545? Maybe some advices?
P.S. Which pin on video cable is for backlight? Because on my cable burned pin 10 or pin 20.

I appreciate any help.
Some photo:

 

[Dadioh]

in the area where i soldered there is plenty of space, one side is on the edge of the square transformer thing, the other one has a dot next to where the resitor goes, but is on a big track. i could get a surface mount one though.

is is not R9730 shown here?

Image

the two in parallel must be the pair next to each other in my pic ??

If you have the mbp13 then they don't use the pair of current sensing resistors. I am on the road right now so can't look in more detail. If you are talking about a single standalone resistor then you a probably looking at the one before the inductor as you indicated. The parallel pair are right beside each other on the board but they are only used with the APP001 circuit I think.

----------

Hi Guys,

I'm having some issues with the backlight of my early2011 13" MB Pro i5 after a Coke shower...
Thing is following:
Everything cleaned thoroughly and got a new keyboard. The Macbook powers on just fine and works flawless. But after some time the backlight starts to flicker. When you try to dim the backlight in this state it will switch off completely. Setting a higher brightness works but the display will eventually start to flicker again. You can continue like this to the highest brightness but the backlight will eventually shutdown completely. No getting it back to work in this state. If you switch the computer off and let it sit for like 3-4 hours it will power on just fine with backlight working again(even dimming to lowest level). But after some time it's going to fail again.

Any suggestions?
Thanks in advance

That kind of slow degradation almost sounds thermally related. Maybe the WLED driver is overheating? Or you may have a cold solder joint that starts to open up as things heat up and the PCB flexs. First thing I would try is examining it under a microsce if you can get access to one. Look for bad solder joints on the WLED or surrounding components. A solder reflow in that area might solve it if you can't find the specific solder joint in question.

----------

Hello guys,
My friends has Macbook A1278. He had spoiled coke on it. I cleaned it carefully,image is visible,but backlight isn`t working.I`m new to electronics,but I figured out that A2 0402 fuse isn`t open (I don`t know how to say it right in english,but multimeter in beep mode doesn`t beep ). When I connected a with wire it both sides backlight appeared for a moment,then protection worked. And I detected that lcd connector has a burned pin,it was damaged before. So what I need to do?
Buy new cable and fuse? How to check l8545? Maybe some advices?
P.S. Which pin on video cable is for backlight? Because on my cable burned pin 10 or pin 20.

I appreciate any help.
Some photo:
]

You definitely need to replace the lvds cable and the connector itself. Once you have replaced the connector check to make sure there are no shorts to ground on the backlight voltage before connecting everything back up.

I am not at home now to check but those look like about the right spot for the backlight voltage pins. There may be a connector Pinout earlier in the thread.

 

[naKruul]

so which one is the WLED driver?

maybe have a look at this picture

 

[Adam88]

I reaaaaly need help

Hello everybody
I have backlight problem, in my Apple MBP 15" core 2 Duo 2.4 GHz (A1226)
i tried to replaced my old LCD screen with a new one but i still have the same Problem
i think the problem is in an electronic part in the area inticated in the images which is damaged (burned) so please i need help to identify the part because there is no name,

like that one in the yollow square but it's not the same one ( Image from A1297 Motherboard )
i think it's a NAND gates but Am not sure...Thank you

 

[naKruul]

That kind of slow degradation almost sounds thermally related. Maybe the WLED driver is overheating? Or you may have a cold solder joint that starts to open up as things heat up and the PCB flexs. First thing I would try is examining it under a microsce if you can get access to one. Look for bad solder joints on the WLED or surrounding components. A solder reflow in that area might solve it if you can't find the specific solder joint in question.

awesome dude, you were totally right. The Chip i suppose which is the WLED Driver reads "AK15 D68B"
Unfortunately it is a BGA so no hot ironing. Need to find someone who is able to reflow the chip. thanks you so much.

 

[Dadioh]

so which one is the WLED driver?

maybe have a look at this picture
Image

Possibly the small black square package just down and to the left of the top mounting screw. Can you read the part number on top of that?

 

[Dadioh]

Hello everybody
I have backlight problem, in my Apple MBP 15" core 2 Duo 2.4 GHz (A1226)
i tried to replaced my old LCD screen with a new one but i still have the same Problem
i think the problem is in an electronic part in the area inticated in the images which is damaged (burned) so please i need help to identify the part because there is no name,
like that one in the yollow square but it's not the same one ( Image from A1297 Motherboard )
i think it's a NAND gates but Am not sure...Thank you

I don't really have much experience working with the non-unibody models so I won't be much help I'm afraid. But in the last picture that particular package is used for a lot of different devices. It is possible it is a NAND gate but can't really say. The device with the white dot is likely a fuse but you say this isn't an image of your particular board so that probably doesn't help.

 

[Adam88]

Plz help

Hi, Dadioh
First of all thanks for your help
yes it's not from the same Logicalboard but the problem is in a A1226 logicalboard (the first image ), the problem is that i can't recognise it because it's damaged so the point is ,i need the name of the part to replace it with a new one, Like i said it could be a NAND gates but there is no name on it...

 

[naKruul]

Possibly the small black square package just down and to the left of the top mounting screw. Can you read the part number on top of that?

It says 15AK D68B

edit:

It is a 25 Pin Micro SMD (BGA) Package.

I suppose it's from National Semiconductors, maybe LP8551, i just sent an inquiry to them and hope they help with providing which specific driver it is.

Problem is: Pressing on it solves the issue, but after a longer period of time the backlight will fail anyways. I think i have to get a new driver on that logicboard

 

[Dadioh]

It says 15AK D68B

edit:

It is a 25 Pin Micro SMD (BGA) Package.

I suppose it's from National Semiconductors, maybe LP8551, i just sent an inquiry to them and hope they help with providing which specific driver it is.

Problem is: Pressing on it solves the issue, but after a longer period of time the backlight will fail anyways. I think i have to get a new driver on that logicboard

That really sounds like a bad solder joint on the part then. I would try a local reflow of the solder. There are heat guns made for the purpose with a small nozzle to hit just the part itself. Get some Kapton tape and create a protection barrier around the part to protect the other devices from blowing off. Apply some liquid flux and then heat enough to reflow the solder. Do some reading online to determine the method.

Something like this:

http://www.ebay.ca/itm/New-ATTEN-85...602?pt=LH_DefaultDomain_0&hash=item3cbea5287a

Not endorsing it. Just did a quick search on eBay and sorted by price.

 

[torontomac]

Macbook White Unibody 2.26

Hey guys
Just a quick question
I have a macbook white unibody 2.26
machine was working perfect
I needed to test an lcd assembly so I hooked it up to the perfectly working machine and the lcd came on but just stayed white so i checked the lvds cable from the assembly and it had some broken/burnt pins so I hooked up the original assembly and I get the same thing, upon further inspection near the lvds connector on the logicboard I see that a component has blown
So can a bad lcd assembly with a blown lvds cable blow out a good logicboard?
I have included a picture from google and highlighted the component in yellow
Any ideas on what can be done,
I have a few dead boards but not the same model
Could I just bridge it?
Any help would be great
Thanks

 

[Dadioh]

Hey guys
Just a quick question
I have a macbook white unibody 2.26
machine was working perfect
I needed to test an lcd assembly so I hooked it up to the perfectly working machine and the lcd came on but just stayed white so i checked the lvds cable from the assembly and it had some broken/burnt pins so I hooked up the original assembly and I get the same thing, upon further inspection near the lvds connector on the logicboard I see that a component has blown
So can a bad lcd assembly with a blown lvds cable blow out a good logicboard?
I have included a picture from google and highlighted the component in yellow
Any ideas on what can be done,
I have a few dead boards but not the same model
Could I just bridge it?
Any help would be great
Thanks

The picture is not high enough res to zoom in and really see the part or which pins it connects to. However, looking at the general layout of the LVDS connector I am not sure if it has the same pinout as the MBP13 2009 or MB Aluminum Unibody 2008 which are interchangeable. Looks like it is possible that the white unibody has a different LVDS pinout despite using the same connector.

To answer your question it is entirely possible to blow components on the logic board by plugging in a bad LVDS cable or bad LED display. The LVDS connector carries backlight voltage (up to 28VDC) as well as 3.3V power to power the panel.

If you can get a high res closeup of the parts right at the LVDS connector I may be able to figure out the pinout.

 

[naKruul]

first of all i wish everybody in this thread a happy new year.

but now back to my problem:

i got a hot-air station from a local dealer and some flux and kapton tape. but no matter how hard i tried, i did not get the solder to melt for a proper reflow. i tried tipping the side of the bga gently but it won't move.

@dadioh: what temperatures do you set on your station. and can you write down your procedure for a local reflow?

thanks in advance.