MacBook Pro Unibody - No Backlight - Logic Board Question

[Dadioh]

On the cable connection, starting on the same mating side:
Pin 1,2 and 3 short to each other, AND GROUND.

This is the problem. Pins 1, 2, 3 are the backlight and should NOT be shorted to ground. You have an issue in the LVDS cable or in the LCD backlight itself. You have to remove the glass to get at the other end of the cable. Not a fun job but if you are careful and patient you can do it without cracking the glass.

 

[ERRDivideByZero]

UPDATE: MacBook Pro Unibody - No Backlight - LVDS related

Thank you gratabb and Dadioh!

I have ordered a replacement LVDS Cable, should be here by the end of next week (hopefully earlier than that, but that's what amazon says). I am going to take apart the screen within the next couple of days, I got a couple of dents I am going to try to hammer out... and I'm going to be "plasti-dipping" it, as its all scratched up from the previous owner.

I will post an update once I get the cable.

When I get the screen apart, is there anything I should check for?

I found the LVDS connector pinout on the logicboard (in the schematic... should have looked harder), so I figure once I get both ends of the cable, I'll ohm it out and see if its just within the cable that the 3 pins are shorted.

Thoughts?

Thanks again everyone!

 

[tommyjames337]

Mid 2010 13-inch MacBook Pro No Backlight - Suspect R9701

hello Dadioh,

after an extensive search and with the graet help of this forum, i ended up finding the following parts blown.

the 2A fuse (F9800 in schematic)
the 100K resistance (R9701)
and as a it seems the APP_1A wlde driver.
Is there any chance i can find that component? It seems that this is my only problem now...

Hey, rogas! I know you were working on your MacBook Pro years ago, but I was wondering if you (or anyone else who might happen to know) could tell me where R9701 is on Mid 2010 13-inch MacBook Pro logic board? I suspect it is blown for my board too, but since the part names aren't printed on the board, I don't know where it is.

I know for certain that the 5V power supply to the LCD backlight driver (U9701) is not working. I get 0V there. If I power it with 5V myself, it turns on the backlight. So, I know there's something wrong with the 5V that should be powering the driver chip. But the trace from pin 22 of the driver disappears into a via, and I have no clue where I might find R9701.

Thanks!

 

[tommyjames337]

Never mind!!!

Hey, rogas! I know you were working on your MacBook Pro years ago, but I was wondering if you (or anyone else who might happen to know) could tell me where R9701 is on Mid 2010 13-inch MacBook Pro logic board? I suspect it is blown for my board too, but since the part names aren't printed on the board, I don't know where it is.

I know for certain that the 5V power supply to the LCD backlight driver (U9701) is not working. I get 0V there. If I power it with 5V myself, it turns on the backlight. So, I know there's something wrong with the 5V that should be powering the driver chip. But the trace from pin 22 of the driver disappears into a via, and I have no clue where I might find R9701.
Image
Thanks!

Never mind everyone! I found the board file and located the resistor with that. Thanks!

 

[gaven55]

No backlight on water spilled A1297 mid 2009.

Hello guys, I am new here and complete new with macbooks.
So I would appriciate any help.

I got A1297 17" MacBook pro few days ago as dead. So I was thinking if there is possibility to get it back to work.
As nice surprise was finding that laptop is working properly except backlight.
So I opened case and found LVDS connector damaged like its showed on pictures.
https://onedrive.live.com/redir?resid=D571436F44786453!23596&authkey=!AMy3-ldlHQcUvi8&v=3&ithint=photo%2cjpg
https://onedrive.live.com/redir?resid=D571436F44786453!23597&authkey=!ANjRnbgo38oH9zE&v=3&ithint=photo%2cjpg

I dont know where the fuse is situated already but I am expecting it will be on the other side of MB. So I can post pic later, If somebody can find it for me...

The other side of problem is, that I dont have any experiences with soldering SMD...

 

[tiagoncalves]

Hey,hello... I use my MBP 13 (A1278) with an external display since 2009, when I had a liquid accident. I don't have the backlight working, but all the rest is ok, I even see a faint image in the display. I don't know how to test the logic board components, and I don't have anywhere so send it (just apple). So, today I tried to connect the LVDS directly to a power source of 24V. Well... I was great, I could see the display working, with backlight. Now, just a few questions, please...
I connected the 21+22 pins of the LVDS cable to the positive terminal (I had attention to the coax shield), and the 24 pin to the negative. It worked, but then I saw some dark vertical bands on the bottom of the display.
More or less like this (it's not my MBP):

Image

What can be causing this? Are the LED's connected with several rows, and maybe one row isn't working? I know that the pins 24 to 29 are the return lines. I must connect all of them to the negative terminal of my power source? Can it be the problem, because I just have one pin connected?
Thanks.

This week I opened the MBP and have made some solderingns in the LVDS cable. The LVDS conector is broken in the LED backlight pins, and the WLED driver doens't work. So I had cut and connect them to an external power supply, drilling the MBP chassis to pass the cable to the outside. Connecting the pins 21+22 to the positive (+) and the pins 24+25+26+27+28+29 to the negative (-) of a 24,8V power supply I get the LED backlight and I'm able to use the MBP again. I need to have it connected to the power supply, but I'm building a battery circuit to power it. I'll use three 8,5V NiMH PP3 batteries in series to do that.

I'll like to know the carachteristics of the LED circuit inside the MBP 13 mid-2009. I read that the voltage is 27V, and I measure an 60mA current using the power supply. But it was powered by just 24,5V. Now, the fresh charged batteries have 30,5V. Can it damage the LED circuit?

Best regards to all

 

[Goowid]

PBP a1286 no backlight

Hello !
Sorry for my english i'm french
English : I got a MacBook Pro A1286. But the backlight not works on the screen on the keyboard or on the apple logo back. What is broken? thank you !
French : j'ai récupéré un MacBook Pro A1286. Mais le rétro éclairage ne fonctionne plus ni sur l'écran ni sur le clavier et ni sur la pomme au dos. Qu'est ce qui est défaillant ? merci

You can contact me at : ugo.cottin@gmail.com

Bye !

 

[Rolanddes]

Hi guys.

I have a similar problem. I guess that is the place to look for help:

I wanted to replace the thermal paste in my Macbook Pro A1286 Core-i7 15" Early 2011.

I opened up the case as I did so many times before just to vacuum the fans.

But this time I removed the board and cleaned the CPU & GPU with Arctic Silver cleaner. Applied thermal paste neatly as described in so many YT videos.

I traced my steps back and closed the case. Now the computer runs but there's backlight in the screen.

I know that it runs because I hear the boot sound, I see the fans running, I hear the click sounds when I hit volume up/down buttons and brightness up/down bottons. I also connected it to a Samsung TV via HDMI and I can see that it works other than the backlight issue.

I checked the LVDS connector and saw that some of its pins are bent. So I thought that was the "only" problem. I found a spare LCD and connected my MBP to it. But there's no backlight in that as well. So I kept searching about the issue I see that it may be more than the LVDS connecter, it may be some fuse or what not.

So do you guys have a suggestion wheter I can run a diagnostic that will tell me which fuses or capacitors are malfunctioning?

Thanks.

 

[tiagobaracho]

Hi guys.

I have a similar problem. I guess that is the place to look for help:

I wanted to replace the thermal paste in my Macbook Pro A1286 Core-i7 15" Early 2011.

I opened up the case as I did so many times before just to vacuum the fans.

But this time I removed the board and cleaned the CPU & GPU with Arctic Silver cleaner. Applied thermal paste neatly as described in so many YT videos.

I traced my steps back and closed the case. Now the computer runs but there's backlight in the screen.

I know that it runs because I hear the boot sound, I see the fans running, I hear the click sounds when I hit volume up/down buttons and brightness up/down bottons. I also connected it to a Samsung TV via HDMI and I can see that it works other than the backlight issue.

I checked the LVDS connector and saw that some of its pins are bent. So I thought that was the "only" problem. I found a spare LCD and connected my MBP to it. But there's no backlight in that as well. So I kept searching about the issue I see that it may be more than the LVDS connecter, it may be some fuse or what not.

So do you guys have a suggestion wheter I can run a diagnostic that will tell me which fuses or capacitors are malfunctioning?

Thanks.

You have to get the board number, get the schematics and check the fuse... Usually the fuse is a green or brown smd part...no diagnostic will tell you that... The board number is something like 820-2376-A.... Usually it's written on the opposite side of the CPU, so you do not need to remove the board...

 

[Rolanddes]

You have to get the board number, get the schematics and check the fuse... Usually the fuse is a green or brown smd part...no diagnostic will tell you that... The board number is something like 820-2376-A.... Usually it's written on the opposite side of the CPU, so you do not need to remove the board...

Yeah, but how am I gonna be able to know which fuse is broken? I mean even if I get the schematics and know which fuse on the board is called what, how will I know which one is broken?

Thanks.

 

[ERRDivideByZero]

UPDATE: MacBook Pro Unibody - No Backlight

So, here's the update:

I got the LVDS Cable in a couple of days ago, and successfully removed the screen and glass panel without breaking them (what a pain!). Once I got everything off, I double checked to verify that the short across the 3 pins was indeed within the cable, and not on the screen as well. It was just the cable that was shorted to ground.

I replaced the cable successfully, and to my dismay, I still had no backlight. So I figured the worst of the worst case, in that the backlight to the screen was fried despite just having an apparent short in the cable, and bought a new screen.

So I got the screen in today, double checked all the connections, and gave it a go... Nothing... no joy... still no backlight.

Double checked the fuse and the MOSFET, both are still good. Checked the voltage across the 3 pins and I am getting between 3V and 5V (hard to say because its difficult to get a solid connection with the leads). Nothing appears to be shorted to anything it shouldn't be.

So... here I sit, brand new screen and cable, still no backlight, though, as before I still have a picture on the LCD. My only thought is to re-flow the WLED Driver... and hope that its just a loose solder connection or something.

Thoughts anyone?

Thanks again. :-(

 

[l.a.rossmann]

So, here's the update:

I got the LVDS Cable in a couple of days ago, and successfully removed the screen and glass panel without breaking them (what a pain!). Once I got everything off, I double checked to verify that the short across the 3 pins was indeed within the cable, and not on the screen as well. It was just the cable that was shorted to ground.

I replaced the cable successfully, and to my dismay, I still had no backlight. So I figured the worst of the worst case, in that the backlight to the screen was fried despite just having an apparent short in the cable, and bought a new screen.

So I got the screen in today, double checked all the connections, and gave it a go... Nothing... no joy... still no backlight.

Double checked the fuse and the MOSFET, both are still good. Checked the voltage across the 3 pins and I am getting between 3V and 5V (hard to say because its difficult to get a solid connection with the leads). Nothing appears to be shorted to anything it shouldn't be.

So... here I sit, brand new screen and cable, still no backlight, though, as before I still have a picture on the LCD. My only thought is to re-flow the WLED Driver... and hope that its just a loose solder connection or something.

Thoughts anyone?

Thanks again. :-(

Reflowing won't fix ****. Don't bother with that nonsense. You can just solder all around with flux and hit each pin, but **** reflowing nasty liquid damaged lead free five year old solder.

What do you get measuring on backlight side of C9799(black probe) and ground(red probe) on diode mode with your multimeter? 0.531? 0.499? 0.519? OL? Do this measurement with no power applied.

What voltage is there at backlight output when you turn this on?

You will almost never have a ****ed up LVDS cable without also having a ****ed up LVDS connector.

 

[ERRDivideByZero]

Backlight issue - C9799

Reflowing won't fix ****. Don't bother with that nonsense. You can just solder all around with flux and hit each pin, but **** reflowing nasty liquid damaged lead free five year old solder.

What do you get measuring on backlight side of C9799(black probe) and ground(red probe) on diode mode with your multimeter? 0.531? 0.499? 0.519? OL? Do this measurement with no power applied.

What voltage is there at backlight output when you turn this on?

You will almost never have a ****ed up LVDS cable without also having a ****ed up LVDS connector.

Thank you for the quick reply!
I would love to test that and post results, however I don't have the correct boardview file, so I am not sure of the location of said cap.

In the following image, would you be able to identify it for me? (Don't mind the MOSFET, I've already replaced it)

https://www.dropbox.com/s/ot5oor7lrqh8m3a/_MG_0013.JPG?dl=0

Let me know if you need a different area, but based on the schematic, I found L9701, and I can see the trace connecting it to Pin 24 off the WLED driver. so I think I'm close.

Thanks again!

 

[l.a.rossmann]

If you don't have a boardview you're ****ed and working blind, find one online for ten or twenty bucks.

 

[ERRDivideByZero]

Okay, so, I managed to dig around a bit, and I found the boardview files that are correct and I believe I found the cap. I'll do some measurements and report back.

 

[ERRDivideByZero]

Okay, so here are the findings:

With the DMM set to Diode mode, and the Positive (Red) Lead on a ground:

C9797: .0F (out of range)
C9799: .0F (out of range)
C9796: .0F (out of range)

I swapped leads, and still come up with the same results. There was no "movement" before getting to these values. And this ".0F" is where the multimeter is normally with open connections.

I double checked to verify that the meter was working correctly, by putting both leads together (shorting), I get 0.000 V.

I swapped the points to verify that all of the capacitors were indeed shorting to ground, which they were, all of the opposite side readings (GND) were 0.000 V when in diode mode.

I then moved down the line to D9701.
In circuit, I get .204V with the Negative (Black) Lead on the striped side of the diode, and the Positive lead on the opposite side. By swapping the leads, I get ".0F"


At this point the above measurements are with the board not powered up. I'm not sure if I will be able to get to those if I put power to the board. If I figure out a nice way to do so without shorting anything or breaking any cables what should the measurements be?


Thanks for the help!
Where to next?

 

[tommyjames337]

A1297 17-inch MacBook Pro (820-2390)

Howdy everyone!

I'm trying to fix my cousin's MacBook Pro.
Does anyone have the boardview file for the early 2009 17-inch MacBook Pro (820-2390)? I have the schematic, but I'm finding it very difficult to get ahold of the brd file. Any help would be much appreciated!

Thank you so much!

 

[ERRDivideByZero]

Howdy everyone!

I'm trying to fix my cousin's MacBook Pro.
Does anyone have the boardview file for the early 2009 17-inch MacBook Pro (820-2390)? I have the schematic, but I'm finding it very difficult to get ahold of the brd file. Any help would be much appreciated!

Thank you so much!

Some googling with key terms may help, but I had to buy my schematic (to know which one it was for sure) and as far as the boardview, I managed to dig one up on a Russian/Polish forum. My suggestion, use google chrome and make sure to translate... it may get you just far enough. I bought my schematic from laptop-schematics.com... it took a couple hours, but I got it in an email, they may have the board view for yours as well. Something to check on.

 

[tommyjames337]

Some googling with key terms may help, but I had to buy my schematic (to know which one it was for sure) and as far as the boardview, I managed to dig one up on a Russian/Polish forum. My suggestion, use google chrome and make sure to translate... it may get you just far enough. I bought my schematic from laptop-schematics.com... it took a couple hours, but I got it in an email, they may have the board view for yours as well. Something to check on.

Thank you! Yes, I've seen that the places where you can purchase the schematics also seem to have the boardview. I'd just rather not pay for it since I already have the schematic and just need the other. I've tried searching google for several hours across all forums and countries. I did manage to find it on a Russian forum, but I don't have enough credits to download it. Seems like more work than it's worth. At that point, I'd rather buy the dang thing.

Just thought I'd check to see if anyone had it on here before I go and spend the money as a last resort.

Thanks so much for the advice, though!

 

[udawat]

Good work. I will have a look when I get a chance and see if there are some obvious troubleshooting tips. External display works so I suspect it is not the 9400m. The fact that it was oscillating back and forth in your description may suggest some sort of intermittent connection. Check the liquid spill areas. Sometimes the liquid causes corrosion on the ends of the resistors and caps so they look like they are connected but not actually since the end solder connection rots away. Good starting point anyways. If you can get access to a microscope it would really really help. it is a whole different world when looking at these things under a microscope.

Given the history you may very well spot the problem visually.

Good luck.

Hi,

Following up on the above Post #247 and #195 (case history), i got inspired by @l.a.rossmann 's Youtube repair videos. I now have the correct Board file and access to an oscilloscope.
Hardware: MacBook Pro 13" Mid-2009 A1278 820-2530 A

As suggested by @Dadioh, i traced back the LVDS Data connections to the GPU. R9008 and R9009 shown in the attachment are 4.5K each rather than 100K (as shown in the schematic).

• LVDS_IG_DDC_CLK and LVDS_IG_DDC_DATA are always at 3.3V (bad pull-up resistors?)
• LVDS_IG_PANEL_PWR also has some voltage (i don't remember, maybe 1.6V or 3.3V)
• PPVOUT_S0_LCDBKLT is at 3.3V
• All the 6 Data signals show around 1.6V in the oscilloscope.
• Oscilloscope screen capture of LVDS_IG_A_CLK_N signal is also attached.

What could be the problem? If you people could guide me in the right direction, i would really appreciate it.

 

[ERRDivideByZero]

Follow up - Readings and Voltages with power on

Okay, so here's the follow up, finally had a chance to figure out a way to get power to the board, and the board safely flipped over so I could get readings and make sure everything still appeared to be functioning (LCD, fans and keyboard attached). I used the battery as the power source so I could keep everything "floating"/isolated.

With the DMM set to Diode mode, and the Positive (Red) Lead on a ground:
C9797: .0F (out of range)
C9799: .0F (out of range)
C9796: .0F (out of range)
D9701: .194V (Black lead on stripe and red lead on opposite side)

I then decided to see what I was getting for voltages. I grounded the black lead on a board standoff (double checked to make sure it was a good ground), and took readings from the non-ground side of the following components:

L9701: 11.38V
D9701: 11.38V
C9797: 11.38V
C9799: 11.38V
C9796: 11.38V
C9712: 11.42V

Q9806-
Pin 3: 3.64V
Pin 1,2,5,6: 11.38V

Any suggestions? At this point I'm pretty confused on where to go.
Thanks!

 

[ERRDivideByZero]

Quick side note

Also, on the top side of the board, U9000 (LVDS Interface connection), VIN and VOUT are both reading 3.2 Volts.

 

[ERRDivideByZero]

Another update

Okay, so, after some serious probing and digging around the schematic I checked some resistors. All appeared to be well, until I got to the output side of the WLED Driver... pins 12,13,14,16,17 and 18... all are supposed to have a 10.2ohm resistor on them.

When I checked the resistors, all 6 of them are .1 ohm (might as well be a short).

Any thoughts on this one?

Thanks

 

[daverice]

Major Props

To: @Dadioh, @l.a.rossmann, @cmdrdata, @cpufixer and all the others doing great things pushing back the darkness with the (back)light and knowledge you bring to this forum. Many thanks to you all as you saved yet another MacBook Pro from a premature death...

My adventure: Once upon a time...No, it is more mundane than that. A friend came to me with an A1278 MD313LL/A 2.4GHZ i5 late 2011 MacBook Pro that her cat had knocked a glass of water over on the open and powered on Mac (how many times have we read about that here). Unfortunately she did not discover it until a couple hours later, so it was good and fried inside. She knew I am a computer tech and came to me hoping against hope...

I work on Windows computers and Android tablets, this being only the 2nd Mac I worked inside of (I successfully swapped out a logic board from a now very old iBook as #1). After I opened it I knew it was bad, alot of corrosion and 4 chips actually fried, one partially melted. I quickly confirmed with one of the eBay "We fix liquid damaged LBs" that it was time for a replacement MB. After research and confirming they were compatible, I found an A1278 MC724LL/A 2.7GHZ i7 early 2011 MBP I managed to get for $200 with what the listing lead me to believe was an LVDS cable issue. The good news...The LB was good, as were almost all of the other parts inside...The bad news...The MC724 was dropped and the case was badly dented with, unfortunately the right hinge mount point broken on the LCD assembly. From what I Googled before I bought it, the MD313 and the MC724 had pretty much interchangeable parts and this was confirmed by installing the MD313s hard drive (undamaged from the water spill) into the MC724 and it booted to login with no issues! All I needed to do is to do an Option boot as the MC724 was confused about the new boot drive until I manually selected it to boot from. Ok, this is easy...swap the insides from the MC724 with damaged case into the almost pristine, but water damaged MD313...IFixit Guides are great!!! Got it all together and press the Power Button and...wait for it...NO video or Backlight!

Well that is when I met you all and gained alot of knowledge about the intricacies of the MBP's backlight. I started out looking for no video as I had nothing even after I found this and I used my flashlight to find a blank screen. I learned that water spills can also damage the LCD. As it turns out the spill did damage the original LCD. I purchased a replacement LCD assembly for the 2011 A1278 series and installed it I again powered on and still no video, but this time I could see everything I was supposed to see with my flashlight. The water damaged LCD blew the 0603 (0402 for older MBPs) fuse almost everyone else here has found to be blown. I then took it to a local LB repair place and replaced the fuse. I do not have the equipment nor the skill to solder tiny parts on to a component dense LB! I know when I am over matched and turn to the experts..and now I have a totally working MC724LL/A in an MD313LL/A case!!! I am typing this post on the newly resurrected MBP now...

Also, I did have a PRAM/SMC reset issue in the middle of all this, but that mysteriously fixed itself after a couple of days. I still don't know what caused that...I could not have gotten to this happy place without you guys. I really appreciate all the hard work, willingness to share knowledge/experience and your patience working with we, the less knowledgeable...Thank you!

I wish I counted all the MBPs you saved here while I read through every post in this thread...Anyone need a cat?

 

[Dadioh]

Okay, so, after some serious probing and digging around the schematic I checked some resistors. All appeared to be well, until I got to the output side of the WLED Driver... pins 12,13,14,16,17 and 18... all are supposed to have a 10.2ohm resistor on them.

When I checked the resistors, all 6 of them are .1 ohm (might as well be a short).

Any thoughts on this one?

Thanks

They are probably meant to be 0ohm resistors then. Schematics don't always match what they implement. These resistors control the current to the LED strings so Apple can adjust them slightly to get the default brightness that they want. This won't be your issue.

----------

Hi,

Following up on the above Post #247 and #195 (case history), i got inspired by @l.a.rossmann 's Youtube repair videos. I now have the correct Board file and access to an oscilloscope.
Hardware: MacBook Pro 13" Mid-2009 A1278 820-2530 A

As suggested by @Dadioh, i traced back the LVDS Data connections to the GPU. R9008 and R9009 shown in the attachment are 4.5K each rather than 100K (as shown in the schematic).

• LVDS_IG_DDC_CLK and LVDS_IG_DDC_DATA are always at 3.3V (bad pull-up resistors?)
• LVDS_IG_PANEL_PWR also has some voltage (i don't remember, maybe 1.6V or 3.3V)
• PPVOUT_S0_LCDBKLT is at 3.3V
• All the 6 Data signals show around 1.6V in the oscilloscope.
• Oscilloscope screen capture of LVDS_IG_A_CLK_N signal is also attached.

What could be the problem? If you people could guide me in the right direction, i would really appreciate it.

It is odd that PPVOUT_S0_LCDBKLT is 3.3V. In non-boosted state it should be 12V. The WLED driver then boosts it up to 30ish Volts. Sounds like the WLED driver is bad. Do you get 12V leading into WLED circuit from the fuse through the FET?

----------

To: @Dadioh, @l.a.rossmann, @cmdrdata, @cpufixer and all the others doing great things pushing back the darkness with the (back)light and knowledge you bring to this forum. Many thanks to you all as you saved yet another MacBook Pro from a premature death...

.
.
.

I wish I counted all the MBPs you saved here while I read through every post in this thread...Anyone need a cat?

Great to hear stories like this. I haven't spent much time here because I have so much on my plate now but check in once in a while. The other guys you mention are great and I appreciate their great input as much as you do. I wish I could help everyone but there only so many hours in a day.

P.S. I already have a bout 20 barn cats but they can't reach my Macs....