MacBook Pro Unibody - No Backlight - Logic Board Question

[MacModMachine]

Here is a photo of the Macbook air boards which i took from one to the other.

I took the wled driver from 820-3209-A to 820-3023-A.

Sorry the photo is not good

for anyone looking for the WLED driver chip shown in these pictures i have 3 left , there free for the taking.


MMM

 

[Dadioh]

@ Dadioh

So, we've arrived at an issue. Since you seem to work on these a lot I'd figure I'd ask what you think (to confirm my suspicion). So, this macbook pro is working perfectly (since replacing the fuse), like it's brand new, when it's plugged in. When it's unplugged it becomes laggy and slow to respond. Video gets choppy as does scrolling web pages.

I've tried all the normal stuff:
Reset Nvram
Reset SMC
Repair permissions
Repair HD

Battery "appears" ok, as do all of the repair tests. Still, this is most likely a bad battery, right? What other options can I try at this point?

I have heard of this sort of issue but never experienced it before. You may want to try running Apple Hardware Test (AHT). If you have a 2010 or earlier it is on the second install DVD. On 2011 and newer I think it gets AHT from the internet connection. Google it to be sure.

You might have a bad sensor would be my guess. AHT should find it.

 

[Dadioh]

First off, I wanted to thank you, Dadioh, for all the great help that you have offered everyone. It's awesome that you're doing that.

Like everyone else, I'm having back light issues. Simply put, you turn the computer, the lights come on for a split second, then turn off. from reading this through this post, I understand it is most likely a capacitor that is causing the issues. However, out of the two that I see on my board, they both give a positive signal for continuity. I didn't want to waste your time by asking the same question everyone else is asking, but I can't find anyone who has asked about my logic board, being a 820-2279-A. It was bought in July of 2008. I also remember reading about the QFN package. I also cannot find that. I truly hope I don't have to replace that, but if need be, I can. I have the tools at college, luckily. I have uploaded some photos of my Logic board for you.

Any help would be great. Thanks again

The reason you can not find relevant information is that you have a white polycarbonate Macbook. All of this discussion is on the unibody Macbooks.

It has been a while since I worked on the old polycarbonate Macbooks. These are not LED backlit. They use a CCFL fluorescent tube which requires an inverter to generate a high voltage for the tube. The area circled below are the ferrites and caps that filter the signals from the logic board to the inverter. The inverter is in the hinge. You could have a bad cable from the logic board to the inverter which is a common problem do to the constant twisting of the cable in the hinge. Also, the inverter itself can fail. They are very cheap on eBay.

First try wiggling the cable from the logic board to the inverter to see if you get intermittent backlight. If not, try replacing the inverter.

Good luck.

 

[Mori3000]

Just if someone is not sure!!!!!!!

I recived my LP8550 LED driver for Macbook Pro A1278 2011.

And i tried this driver on macbook air A1369 2012. and it seems that it works and it is the same components

 

[peislander]

Flux

Hi guys

I got tired of my Flux that i,m using, when i apply heat it become dark and like glue, and very difficult clean, is there any better than this?which kind of flux are you useing for soldering?

Thanks

I tried a few but I like Amtech NC-559-ASM the best.Not the stuff from china but made in the USA.
Cheers

 

[Mori3000]

I tried a few but I like Amtech NC-559-ASM the best.Not the stuff from china but made in the USA.
Cheers

Thanks but does it needs cleaning or not?

 

[Mori3000]

Pin 1 is ground so you could live without it. But pin 8 goes straight to the Cougar so you are going to have to find what via it connects to and try to link to that.

See attachments.

Hello Dadioh

I tested that with a working board, it seems that the pin one which is mentioned as ground is on the other side of the connector, i think we need to count from the other side and that will be pin number 23 and 30.

Which writen NC from them.

can you confirm this please?

thanks

 

[peislander]

Thanks but does it needs cleaning or not?

It says no clean but I always clean board after soldering.Here's a link from a good seller.
Cheers
http://www.ebay.com/itm/1pc-10cc-AM...327?pt=LH_DefaultDomain_0&hash=item2c66cd43ef

 

[cetchmoh]

Hello everybody!

I've been lurking in this thread for quite some time and I thank you all for this wonderful collection of information.

I myself got a damaged Macbook Pro 13" early 2011. The backlight is not working, and I'm running out of ideas at the moment.

Perhaps you guys can help.

Macbook A1278 early 2011.

What's wrong:
Liquid entered from the bottom of the Macbook. No backlight.

What I did:
Cleaned board with isopropyl. Some damage noticed to LVDS cable and LVDS socket connector. 3A fuse was blown.
Stupidly tried to bridge the fuse with a piece of wire. Turned on macbook, notices sparkles and smoke from LVDS connector. Did only more damage to cable and socket connector.

So now I replaces the LVDS cable, the LVDS socket connector (30 pins) and the blown fuse. Turned the macbook on, and still no backlight

I tested the display on a friends machine, and it works. I assumed that if the WED driver is broken, the fuse would blow, but the fuse is still intact.

I'm running out of ideas and I really need some pointers where to look at. I cannot afford replacement of the logic board

I have a usb microscope and can supply pictures if needed. Has anyone an idea what could be wrong? Or which components I should measure to start debugging the problem?

Thank you guys.

 

[enxm2004]

I replaced the lcd of my Macbook air, 11 inches model A1370, 2011 and now the backlight does not work. I soldered some wires to test some signals, As I understood the backlight driver (LP8550) does not boost the voltage to light up the LEDs.

What is weird for me is that the enabling signal coming from the microcontroller is zero and the resistance is 30ohm which should be 100K according to the schematics....

any ideas?

I am going to replace the driver to see if it helps.

Here i got some explanations of what I did so far:

http://www.ifixit.com/Answers/View/119669/Why+is+the+backlight+not+working

The highlighted signal is LCD_BKLT_EN which should enable the Mosfet and accordingly the driver, but it is actually grounded (30 ohm instead of 100 K)


thanks
Navid

 

[cetchmoh]

Hello everybody!

I've been lurking in this thread for quite some time and I thank you all for this wonderful collection of information.

I myself got a damaged Macbook Pro 13" early 2011. The backlight is not working, and I'm running out of ideas at the moment.

Perhaps you guys can help.

Macbook A1278 early 2011.

What's wrong:
Liquid entered from the bottom of the Macbook. No backlight.

What I did:
Cleaned board with isopropyl. Some damage noticed to LVDS cable and LVDS socket connector. 3A fuse was blown.
Stupidly tried to bridge the fuse with a piece of wire. Turned on macbook, notices sparkles and smoke from LVDS connector. Did only more damage to cable and socket connector.

So now I replaces the LVDS cable, the LVDS socket connector (30 pins) and the blown fuse. Turned the macbook on, and still no backlight

I tested the display on a friends machine, and it works. I assumed that if the WED driver is broken, the fuse would blow, but the fuse is still intact.

I'm running out of ideas and I really need some pointers where to look at. I cannot afford replacement of the logic board

I have a usb microscope and can supply pictures if needed. Has anyone an idea what could be wrong? Or which components I should measure to start debugging the problem?

Thank you guys.

I attached some pictures:





Is there any hint how I could measure the resistance of the connections from the WED driver... from what I learned from this thread it's a BGA package, so I don't have any "legs" where I could attach my multimeter.
Would it help to measure the voltage for every pin on the lvds cable to ground? Does someone have some values I could compare mine to?

Thank you guys in advance!

 

[PokerMunkee]

Need some advice.

Have a 15" Macbook Pro A1286 with no backlight. Bought a replacement LCD screen on eBay and have the same results. We have another A1286 as a spare that works fine, so we decided to put the original LCD screen on it to see if it was indeed good. Now the spare laptop is doing the exact same thing, no backlight.

Any ideas what we should be looking at? I'm guessing I have 3 good LCD screens, and perhaps two bad logic boards now. Or a fuse is blown on both. We are having problems finding the fuse.

Getting really frustrated with this. Any help on what to test next would be appreciated!

 

[fmoras]

Dadioh Thank you very much! I found a specialist who can change the lvds connector and i ordered it from ebay. When i finish the project i will inform you for the results. This Thread Really Rocks! thanks again.

I m ready to jump from window.... lvds connector came from ebay. but the specialists here in greece probably sucks. The first specialist who told me that he can handle the problem suddenly told me that his desoldering tool can't do that. I was searching about 2 weeks to find someone who got the skills .. i found one who told me that somebody engraves the pins of lvds connector and the changing lvds method it can't be successful..... (i don't know why but...) also he told me that DADIOH told me... to bridge the pins ... so i didn't had any other way so i told him to do this.... today he called me and said to me that he can't do it. he try to bridge and it cant be fixed...... I AM TIRED..... i have spent so much time and money and my macbook still is not fixed. If somebody knows what exactly to tell to next genius guy i will find please inform me... the photos of my logic board and my problem are in previous pages in this thread. I'm sorry for writing so much but i am disappointment and i must speak to somebody who understand me...

Sorry for my english too...

 

[Dadioh]

I m ready to jump from window.... lvds connector came from ebay. but the specialists here in greece probably sucks. The first specialist who told me that he can handle the problem suddenly told me that his desoldering tool can't do that. I was searching about 2 weeks to find someone who got the skills .. i found one who told me that somebody engraves the pins of lvds connector and the changing lvds method it can't be successful..... (i don't know why but...) also he told me that DADIOH told me... to bridge the pins ... so i didn't had any other way so i told him to do this.... today he called me and said to me that he can't do it. he try to bridge and it cant be fixed...... I AM TIRED..... i have spent so much time and money and my macbook still is not fixed. If somebody knows what exactly to tell to next genius guy i will find please inform me... the photos of my logic board and my problem are in previous pages in this thread. I'm sorry for writing so much but i am disappointment and i must speak to somebody who understand me...

Sorry for my english too...

That is what I expected. What I said in the earlier post was

If the pins are corroded off then you are really just left with replacing the connector. You "could" try bridging solder from the logic board to the stubs on the connector but being corroded the solder probably won't stick and you would likely melt the plastic of the connector.

Replacing the connector is really not that hard. I have done many of them.

The steps I take are:

1) Remove the old connector with a hot air tool. This destroys the connector but you are throwing it out anyway.
2) Clean the solder completely off the ground pad and off all 30 (or 40 for 15") pins. You want the new connector to sit absolutely flat on the pads without solder bumps holding it up off the board.
3) Apply liquid flux to the area including the ground pad and pins.
4) Place the new connector being careful to align all of the pins on their respective pads.
5) Using fine tipped soldering iron apply a small bit of solder to both ends of the connector shield to tack it in place so that it does not move. It takes a bit of time to heat the ground pad enough that the solder will stick to it. Patience is key.
6) Once the connector is tacked and securely held in place, then start at one end and solder each pin to its corresponding pad. Apply only enough heat to get the solder to flow onto the connector legs. Too much heat endangers the plastic of the connector.
7) Once all of the connector pins are soldered to the pads I move along all connections with a fine dental pick pressing very gently and observing under microscope for any movement. This ensures solid connections and detects incorrect solder connections.
8) Now run a bead of solder along the front edge of the ground strip of the connector. It takes a fair bit of heat to get the ground pad hot enough to wick to the solder so, again, patience.

Done! I think that the trick is that you have to use manual soldering iron technique. Hot air tools are usually too hot and will melt the connector plastic. Maybe it can be done with precise temperature control but the manual soldering iron works every time.

Good luck.

 

[fmoras]

That is what I expected. What I said in the earlier post was

If the pins are corroded off then you are really just left with replacing the connector. You "could" try bridging solder from the logic board to the stubs on the connector but being corroded the solder probably won't stick and you would likely melt the plastic of the connector.

Replacing the connector is really not that hard. I have done many of them.

The steps I take are:

1) Remove the old connector with a hot air tool. This destroys the connector but you are throwing it out anyway.
2) Clean the solder completely off the ground pad and off all 30 (or 40 for 15") pins. You want the new connector to sit absolutely flat on the pads without solder bumps holding it up off the board.
3) Apply liquid flux to the area including the ground pad and pins.
4) Place the new connector being careful to align all of the pins on their respective pads.
5) Using fine tipped soldering iron apply a small bit of solder to both ends of the connector shield to tack it in place so that it does not move. It takes a bit of time to heat the ground pad enough that the solder will stick to it. Patience is key.
6) Once the connector is tacked and securely held in place, then start at one end and solder each pin to its corresponding pad. Apply only enough heat to get the solder to flow onto the connector legs. Too much heat endangers the plastic of the connector.
7) Once all of the connector pins are soldered to the pads I move along all connections with a fine dental pick pressing very gently and observing under microscope for any movement. This ensures solid connections and detects incorrect solder connections.
8) Now run a bead of solder along the front edge of the ground strip of the connector. It takes a fair bit of heat to get the ground pad hot enough to wick to the solder so, again, patience.

Done! I think that the trick is that you have to use manual soldering iron technique. Hot air tools are usually too hot and will melt the connector plastic. Maybe it can be done with precise temperature control but the manual soldering iron works every time.

Good luck.

Thank you DADIOH.... I wish you were from greece to solve all my problems.. I haven't see my macbook yet . at morning i will go to take it and see what the genius guy do... The worst situation i think is that he maybe destroy the default lvds connector and not the second that i gave him to hands , so i can replace it. What about the "i found one who told me that somebody engraves the pins of lvds connector and the changing lvds method it can't be successful..... " is this diagnose right or he can't change the lvds and told me that?

Thank you again.

 

[PokerMunkee]

Can't find the fuse on this two year old MBP 15" A1286.

Here is a picture. I know it's dirty, will clean it up once I buy some alcohol.

 

[Dadioh]

Thank you DADIOH.... I wish you were from greece to solve all my problems.. I haven't see my macbook yet . at morning i will go to take it and see what the genius guy do... The worst situation i think is that he maybe destroy the default lvds connector and not the second that i gave him to hands , so i can replace it. What about the "i found one who told me that somebody engraves the pins of lvds connector and the changing lvds method it can't be successful..... " is this diagnose right or he can't change the lvds and told me that?

Thank you again.

You are welcome. Greetings from Canada. His statement about engraved pins makes absolutely no sense. I have soldered many of these connectors. They are meant to be soldered by definition. I can't see how engraving, even it was the case, gets in the way of soldering. Bizarre statement.

 

[Dadioh]

Can't find the fuse on this two year old MBP 15" A1286.

Here is a picture. I know it's dirty, will clean it up once I buy some alcohol.

See attachment. Good luck.

 

[cetchmoh]

I attached some pictures:

[url=http://s7.postimg.org/shhma3n47/connector.jpg]Image[/url]
[url=http://s7.postimg.org/793xso8nb/wed_bga.jpg]Image[/url]
[url=http://s7.postimg.org/q3zoj38p3/wed_bga_closeup.jpg]Image[/url]

Is there any hint how I could measure the resistance of the connections from the WED driver... from what I learned from this thread it's a BGA package, so I don't have any "legs" where I could attach my multimeter.
Would it help to measure the voltage for every pin on the lvds cable to ground? Does someone have some values I could compare mine to?

Thank you guys in advance!

Hey Dadioh, perhaps you can help me out?

I read on my mainboard 820-2936 B, and I found some schematics for this board on the net. Now I'm trying to work out where the fault is.



I started by trying to identify the resistors.



In the middle is the LP8550. I have no idea how I could verify if it's working correctly. The fuse is replaced and I measure 0 ohms. Display connector is replaced.

I read about a boost diode and voltage at the enable pin. Could you give me a pointer where to look for them? What should I measure there?
Due to the fact that the fuse does not blow, I assume I get less or no voltage where I should get the voltage for the backlight. (between ~20 and 32V?). I would like to backtrace my way from there to find the faulty component.

Please help

 

[PokerMunkee]

Wow, would have never found that. Thanks.

Any issues with using 70% isopropyl alcohol to clean?

 

[fixitya]

That cap probably just provides high frequency smoothing of the voltage so it "might" work without it albeit with some high frequency noise. The pair of 2.2uF caps provide the "grunt" in the circuit to smooth the output of the WLED driver into the LC network. See attachment.

I tried Digikey and Newark and they don't seem to stock any. But here is the search detail so you can see if you can find something in stock.

http://www.digikey.com/scripts/dkse...newproducts=0&ptm=0&fid=0&quantity=0&PV13=119

Thanks Dadioh, your suggestion resolved my problem ..Macbook is back working and has backlight after installing that capacitor. Very much appreciated. Thanks again!

 

[SpeedManiac]

my macbook pro 17 inch, start up ok,screen is black, after some water fall on keyboard, but it works perfect on external monitor, any help to find which fuse should I check...here are photos.
edit: and i try LCD on another macbook pro, and it works too

 

[l.a.rossmann]

I have heard of this sort of issue but never experienced it before. You may want to try running Apple Hardware Test (AHT). If you have a 2010 or earlier it is on the second install DVD. On 2011 and newer I think it gets AHT from the internet connection. Google it to be sure.

You might have a bad sensor would be my guess. AHT should find it.

Is this board an 820-2879? This running slow on the battery is a rampant issue on 820-2879

 

[Dadioh]

my macbook pro 17 inch, start up ok,screen is black, after some water fall on keyboard, but it works perfect on external monitor, any help to find which fuse should I check...here are photos.
edit: and i try LCD on another macbook pro, and it works too

I believe it is the component highlighted below. Looks like it has a P or an F silkscreened on top. Picture is too blurry to be certain.

 

[Dadioh]

Is this board an 820-2879? This running slow on the battery is a rampant issue on 820-2879

Interesting. Only thing I can think of is that the battery is sending multiple messages over its I2C link to the SMC and causing constant interrupts to the processor. But why would that only be the case when running on battery? If someone knows the solution please share.