MacBook Pro Unibody - No Backlight - Logic Board Question

[mazzano4]

Thanks so much those who replyed, so its not this fuse problem then

 

[mazzano4]

If it is this model then it is a CCFL backlight and not an LED backlight. The CCFL is a fluorescent tube and requires an inverter to generate a high voltage for the tube so it is possible that you have a bad inverter or the cable could be bad. But I have never worked on that model so I can't help with locating the inverter.

Hi, i think mine is the upgraded display, this is what i got from your link...17.0" color "antiglare widescreen TFT display" with a 1680 by 1050 native resolution. Apple reports that the default display also supports "1280 by 800, 1152 by 720, 1024 by 640, and 800 by 500 at 16:10 aspect ratio; 1280 by 1024 at 5:4 aspect ratio; 1280 by 1024 at 5:4 aspect ratio stretched; 1024 by 768, 800 by 600, and 640 by 480 at 4:3 aspect ratio; 1024 by 768, 800 by 600, and 640 by 480 at 4:3 aspect ratio stretched; 720 by 480 at 3:2 aspect ratio; 720 by 480 at 3:2 aspect ratio stretched".

*A higher-resolution 1920x1200 LED-backlit "antiglare" or "glossy" display is available by custom order. Apple reports that this display additionally supports "1680 by 1050, 1280 by 800, 1152 by 720, 1024 by 640, and 800 by 500 at 16:10 aspect ratio; 1280 by 1024 at 5:4 aspect ratio; 1280 by 1024 at 5:4 aspect ratio stretched; 1600 by 1200, 1024 by 768, 800 by 600, and 640 by 480 at 4:3 aspect ratio; 1600 by 1200, 1024 by 768, 800 by 600, and 640 by 480 at 4:3 aspect ratio stretched; 720 by 480 at 3:2 aspect ratio; 720 by 480 at 3:2 aspect ratio stretched".


But in " About ThisMac " Mine is saying it is a " built in colour lcd display" but with a resolution of 1920 x 1200.
Does tis make it the LED or LCD display. Im a bit confused now.

 

[mazzano4]

Hi guys,

I dont know if this is bad news for me or not, my screen is the LED version, i put my serial number into a serial number checking site, and it gave me this information....

Hard Drive: - 320 GB, 5400rpm.
Hard Drive Brand: - Unknown.
Drive Bus: - Serial-ATA
Optical Drive: - This unit has an 8x SuperDrive built in.
Optical Bus: - Ultra ATA/100
Other Media: - -

Display Size: - 17-inch.
Graphics Card: - NVIDIA GeForce 8600M GT
Card Memory: - 512 MB
Max. Resolution: - 1920x1200
BLU / Coating: - LED, Hi-Res, Glossy.


So does this mean its something on the board, i dont really want to pull the screen apart if theres no inverter in there.

Any help please anyone,thanks.

 

[midijamm]

hi-res backlight

It seems so that there is no inverter in that display. I have had so many of those old displays apart I assumed... but now I realize that I never had the Hi-res apart.

Seems very unlikely that a fuse is at fault as the function of the fuse is to self destruct to protect other parts. In the 1260 (the 15" of the same type) the left in/out board contained a fuse for the display and perhaps the chip that sends the proper voltage tho the display????

Wish I could help. Please post what you find out.

 

[Astroboy907]

I used the diode measurement setting on my meter and it was always high, so no diode in reach. Measured from every return to every backlight pin.
I also swapped the probes but no difference.

Just by chance if you know, but how could I test this without a diode setting? I just have a cheap multimeter but need to test a couple LCDs. I can get access directly to the LCD connector.

Edit: I think I founds it's diode setting, stupid me. Helps to have a small assortment of multimeters though!

 

[nisifornizzle]

A1286 820-2850 a

First of all, thanks a lot to Dadioh with your awesome konwledge!

I have a Macbook Pro A1286 Mid 2010 820-2850A. My Backlight is not working, even after changing the display and the LVDS Cable.
I haven't got a water damage but I think there is a different kinda problem.

I located the fuse and I measured about 1Ohm, thats ok right? On the 638Z Chip I measured on the top acrossed pins, and I'm getting 300kOhm, thats ok too right? So I think the fuse isn't the problem.
Where can I measure the Output Voltage for the backlight?

If you see the socket of the LVDS Cable you can see that the Pins 38,39,40 are damaged, and I think according to the schematics they are responsible for the backlight. How can I measure the broken points from the socket?
Are there any resistors I can measure, because someone located the problem on a resistor?

So Dadioh, i know you have to answer a lot of requests, but I would really appreciate it if you could help me. Thanks in advance!!!

 

[Astroboy907]

If you see the socket of the LVDS Cable you can see that the Pins 38,39,40 are damaged, and I think according to the schematics they are responsible for the backlight. How can I measure the broken points from the socket?
Are there any resistors I can measure, because someone located the problem on a resistor?

Just a thought, have you tried cleaning those pins with high percentage isopropyl alcohol? I've seen some that have damages that clean up fairly well with alcohol. Might help if it is just a corrosion short.

 

[Reballer]

A1278 No Backlight

Hello Everyone,

I have an A1278 with board number 820-2879. I am not getting any backlight. I have tried the board with a known working display with the same results.

I have checked to make sure PPVOUT_SW_LCDBKLT is good with 19V. I also checked for PP3V3_LCDVDD_SW_F and PP3V3_S0_LCD_F and both have 3.3V.

Does anyone have any suggestions?

Thanks

 

[nisifornizzle]

Just a thought, have you tried cleaning those pins with high percentage isopropyl alcohol? I've seen some that have damages that clean up fairly well with alcohol. Might help if it is just a corrosion short.

Yeah, but if you zoom in the picture, you'll see, that there are these pins missing, and I think that's the problem, right?

Can I measure the output voltage on these pins or on the logic board, if yes where I'm supposed to measure and what voltage I should be measuring? Thanks

 

[dieett]

App001

Bad lvds cable
Bad lvds connector
Bad LEDs in display

Can you try a known good display?

----------



As far as I know the APP001 is not publicly available. You would need to salvage one off a spare parts board.

I have 20 pieces from China can come! (now available in Germany)

 

[Astroboy907]

In response to my previous post

Recently I won a lot of macbook screens off of eBay. I got them today and put one on my Mac, and it works awesome. I did notice the LVDS got a bit hot though, but thought nothing to it. Put another screen on to test, and my backlight dies. Of course, it's the fuse so I replace that and put the first screen on. Backlight comes on, but within a few seconds the LVDS is burning and I see smoke. Pulled the battery. And of course, I put the second screen back on and it blows my fuse again- kind of. It's now reading approx 1.35k. No backlight on the original screen... Don't know if its the WLED or not...

I have another couple fuses but I don't want to solder another if its going to break again... Plus the fuse doesn't seem to be burnt.

Ok, so I got a new LVDS cable for it, tried and no luck. Replaced the fuse, still nothing. So I checked around the APP_1A chip as much as I could (which I assume is the LED driver circuit). From what I can tell, the resistors for the LED returns are all reading shorted (Approx 0.6 ohms, which on my cheap mulitmeter I assume shorted). They should all be reading 10.2 ohms. Could this be the reason my backlight isn't working? I unplugged the cable with the battery connected (D'oh!), could it have shorted those resistors?

The only thing I could do now is check voltages and the FET. How does one check a FET??? As always, any help you give is immensely appreciated.
-Thomas

 

[vasago]

Early 2011 MBP15

So the last 3 pins are the backlight pins on the MBP15". You have soldered them together and taken that connection to where? If the traces were corroded away then you can find the Diode or one of the caps and take it to there. Are you getting the 27V out of the backlight driver circuit?

Hello again Dadioh. Sorry for my long pause, but I had some things to work out !So the last time you said to post photos where you can see where I get those 3 backlight pins...

 

[Dadioh]

In response to my previous post
Ok, so I got a new LVDS cable for it, tried and no luck. Replaced the fuse, still nothing. So I checked around the APP_1A chip as much as I could (which I assume is the LED driver circuit). From what I can tell, the resistors for the LED returns are all reading shorted (Approx 0.6 ohms, which on my cheap mulitmeter I assume shorted). They should all be reading 10.2 ohms. Could this be the reason my backlight isn't working? I unplugged the cable with the battery connected (D'oh!), could it have shorted those resistors?

The only thing I could do now is check voltages and the FET. How does one check a FET??? As always, any help you give is immensely appreciated.
-Thomas
View attachment 438234

Some of the Macbooks were 10ohm but some were 0ohm on the returns. I assume that was a way to set the full screen brightness level. I would not necessarily trust the schematic since some of the schematics in the wild appear to be pre-production and could easily have been updated/tweaked for final production. I believe that your resistors are correct at 0ohms.

----------

Hello again Dadioh. Sorry for my long pause, but I had some things to work out !So the last time you said to post photos where you can see where I get those 3 backlight pins...

Props for some innovative soldering

So are you getting backlight voltage being delivered to those pins now? Maybe give us a quick summary so we know current status.

 

[MBP15owner]

Hi,

a Great Thread, with many Informations and wonderfull Users here

I'm searching so long via Google to find an Fix for my Backlight Problem
and now I find this Great Thread.... Yeah

I have read all the Sites of this Thread and I'm very flashed from this
Great User helpings. Is absolutely Unique and fantastic.

So, my Macbook have no Backlight now.... yes it was an Waterdemage.

I have allready clean up my complete MBP and Logicboard with Isopropanol Alcohol. The Display was defect and I purchase a new one.

I think the Fuse for the Backlight is Broken too, but i cannot find the Fuse on
My Logicboard....

I Hope anyone can helb me to Locate the Fuse....

Details from my Macbook:
MBP15 9.1 Mid 2012 (no Retina) i7 2,3Ghz A1286

Here two Logicboard Pictures from iFixit :

I have find a Fuse under the Right Fan ... But i don't now is this the right one.

By the Way, sorry for My English it was more than twenty years ago, that I
wrote in English. I hope you all understands what i mean and where my Problem is. Many Thanks for all People in this fantastic and very helpful Thread.

Nice Greetings from good old Germany

 

[vasago]

Some of the Macbooks were 10ohm but some were 0ohm on the returns. I assume that was a way to set the full screen brightness level. I would not necessarily trust the schematic since some of the schematics in the wild appear to be pre-production and could easily have been updated/tweaked for final production. I believe that your resistors are correct at 0ohms.

----------



Props for some innovative soldering

So are you getting backlight voltage being delivered to those pins now? Maybe give us a quick summary so we know current status.

Where I soldered those 3 pins, I am not getting any voltage.
So this is the MBP 15 early 2011 that came with no video. The LVDS connector was fried and the LVDS cable too. Changed the cable and the connector. Those 3 pins were fried in the board, so i tooked those from the other side of the motherboard. No shorts on LVDS conn. pins so I am not sure where those 3 pins are going. What i made is that I unsoldered the cable with those 3 pins from the other side and I powered the mac to see if I have video, without backlight, only video ... and NO, there is no video, so ...

 

[Dadioh]

Hi,

a Great Thread, with many Informations and wonderfull Users here

I'm searching so long via Google to find an Fix for my Backlight Problem
and now I find this Great Thread.... Yeah

I have read all the Sites of this Thread and I'm very flashed from this
Great User helpings. Is absolutely Unique and fantastic.

So, my Macbook have no Backlight now.... yes it was an Waterdemage.

I have allready clean up my complete MBP and Logicboard with Isopropanol Alcohol. The Display was defect and I purchase a new one.

I think the Fuse for the Backlight is Broken too, but i cannot find the Fuse on
My Logicboard....

I Hope anyone can helb me to Locate the Fuse....

Details from my Macbook:
MBP15 9.1 Mid 2012 (no Retina) i7 2,3Ghz A1286

Here two Logicboard Pictures from iFixit :

Image

Image

I have find a Fuse under the Right Fan ... But i don't now is this the right one.

By the Way, sorry for My English it was more than twenty years ago, that I
wrote in English. I hope you all understands what i mean and where my Problem is. Many Thanks for all People in this fantastic and very helpful Thread.

Nice Greetings from good old Germany

Welcome to the thread. The ifixit photos do not have enough resolution for me to see the individual parts. The fuse will usually be somewhere near the lvds connector either on the front or the back. Can you take a high resolution photo of your board just in the area around the connector both front and back and post here. Then is should be able to identify the fuse.

----------

Where I soldered those 3 pins, I am not getting any voltage.
So this is the MBP 15 early 2011 that came with no video. The LVDS connector was fried and the LVDS cable too. Changed the cable and the connector. Those 3 pins were fried in the board, so i tooked those from the other side of the motherboard. No shorts on LVDS conn. pins so I am not sure where those 3 pins are going. What i made is that I unsoldered the cable with those 3 pins from the other side and I powered the mac to see if I have video, without backlight, only video ... and NO, there is no video, so ...

Ok. So you are at the stage of trouble shooting the WLED driver then. Check that it is getting 12V input and enable signal 3V.

 

[MBP15owner]

Hi Dadioh,

many Thanks for your Help

Now i took some new Pictures that i shoot with my DSC-F828 and i hope there are much better for locate the Fuse

Sorry for Image Size, but I think it`s possible to do not resize it.

The Last Picture ist the Fuse that I found it in the near of the Fan Connector, it is a SMD with an "P" on it. I`m not sure is it the right one ???

And now Here we go with my new Pictures :



Uploaded with ImageShack.us



Uploaded with ImageShack.us



Uploaded with ImageShack.us



Uploaded with ImageShack.us



Uploaded with ImageShack.us



Uploaded with ImageShack.us



Uploaded with ImageShack.us

So I have much more Pictures taken, but I hope these Pictures, that I upload
is enough to find the Fuse

Nice Greetings from Germany and Thanks for your fantastic help

 

[Dadioh]

Hi Dadioh,

many Thanks for your Help

Now i took some new Pictures that i shoot with my DSC-F828 and i hope there are much better for locate the Fuse

Sorry for Image Size, but I think it`s possible to do not resize it.

The Last Picture ist the Fuse that I found it in the near of the Fan Connector, it is a SMD with an "P" on it. I`m not sure is it the right one ???

And now Here we go with my new Pictures :

So I have much more Pictures taken, but I hope these Pictures, that I upload
is enough to find the Fuse

Nice Greetings from Germany and Thanks for your fantastic help

You got the fuse location right. It looks like an 0603 package. I don't have a schematic for that model so I am not sure if it is a 2A fuse or a 3A fuse. Maybe someone with the schematic can chime in. I suspect the 15" models use 3A however.

 

[MBP15owner]

You got the fuse location right. It looks like an 0603 package. I don't have a schematic for that model so I am not sure if it is a 2A fuse or a 3A fuse. Maybe someone with the schematic can chime in. I suspect the 15" models use 3A however.

Hi Dadioh,

cool, you are absolutely sure it is the Backlight Fuse ?

 

[Dadioh]

Hi Dadioh,

cool, you are absolutely sure it is the Backlight Fuse ?

Yes. That is the backlight fuse. Measure it with your meter. If it shows Megaohms then it is blown. It should measure close to zero ohms.

 

[MBP15owner]

Yes. That is the backlight fuse. Measure it with your meter. If it shows Megaohms then it is blown. It should measure close to zero ohms.

Great, so many Thanks for your Help

Than I Measure the Fuse now .... please one more Question.... Where is the
WLED-Driver on my Logicboard, you have see it too. ?

 

[Dadioh]

Great, so many Thanks for your Help

Than I Measure the Fuse now .... please one more Question.... Where is the
WLED-Driver on my Logicboard, you have see it too. ?

I believe it is the small square package just to the left of the fuse. Surrounded by all the resistors. 6 or 7 of those resistors will be the return lines from the LEDs in the display.

The WLED driver is a BGA package so it is unlikely that you will be replacing that if it is bad.

 

[MBP15owner]

An Amazing Thread !!!

I believe it is the small square package just to the left of the fuse. Surrounded by all the resistors. 6 or 7 of those resistors will be the return lines from the LEDs in the display.

The WLED driver is a BGA package so it is unlikely that you will be replacing that if it is bad.

OK, thanks for your evaluation concerning the WLED-Driver.

I´m very optimistic that replace the Fuse bring me my Backlight back, I
have purchase a new Panel and clean careful the Logicboard and all
Connections, that will work... certainly

Now ist the next Step for me to find sombody in Germany that have enough soldering Skills and Equipment to solve my Backlight Problem and put a new
Fuse on my Logicboard.

For me this is too difficult, the Fuse to replace.... there is so mini and all around so little place. Thats unfortunately nothing for me and my old Eyes & shaky Hands

So Dadiho many many Thanks for you again, it`s an fantastic and amazing Thread which you started here.

Respect for you and all other helpful Users

i hope your Tread can much more People help to bring their Backlight back without replace the Logicboard through Apple

Nice Greetings from good old Germany
One World - One Future, That`s the Way

Love Greetings to all Users

 

[Astroboy907]

Some of the Macbooks were 10ohm but some were 0ohm on the returns. I assume that was a way to set the full screen brightness level. I would not necessarily trust the schematic since some of the schematics in the wild appear to be pre-production and could easily have been updated/tweaked for final production. I believe that your resistors are correct at 0ohms.

Ok, good to know. I tested the some of the WLED voltages today, looks better than I expected, heres what I got.


Here are a few pics and schematics posted a while back...
View attachment 302119
View attachment 302120
View attachment 302121

Which would lead me to think a faulty 638z chip? Currently it is not shorted in any places it should not be, as far as I can tell. The 300k resistor is also giving me fits as well, R9808. Most of the time I can't get a reading on it. I did think I got it to say 300k at one test, but any other tests it would not read that (bad solder contacts?). If that was blown/incorrectly soldered could it cause the 638z to fail?

Edit: tried adding some solder to the contacts in case the thermal shock from me replacing the fuse broke a contact. Got it to register 301k, but nothing changed in the circuit. Looks like the 638z or the odd little Q9807 thingy from the schematic. And all this because I had a hot ldvs cable and unplugged the screen with the battery in... My voltage dropped a bit too, to 10.6 volts. This could be because I'm solely on the battery though, right?

Apart from that I am having problems booting from AC power. Currently the board only likes to boot from the battery. The battery is recognized (orange/amber light), and I assume charged (battery indicator lights blink), but the board just doesn't boot with AC. I do have a 3rd party charger (old one frayed out), could that cause it? Either way I'm hoping it's a SMC issue and can be fixed. Thanks for your help!

 

[Reballer]

A1278 No Backlight

Hello Everyone,

I have an A1278 with board number 820-2879. I am not getting any backlight. I have tried the board with a known working display with the same results.

PPVOUT_SW_LCDBKLT has 19V. I also checked for PP3V3_LCDVDD_SW_F and PP3V3_S0_LCD_F and both have 3.3V. I have changed the WLED driver. Fuse and connector are good.

Any suggestions?

Thanks