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MacBook Pro Unibody - No Backlight - Logic Board Question

This thread is a sight for sore eyes (literally).

MBP i5 13, late 2011, water damaged, off eBay.

At this point I seem to have everything except trackpad (another thread, another day) and backlight working.

My motherboard is the version with the LVDC connector at a 45 degree angle. There are burned pins on the cable (on order), the connector side looks OK.

Nearby there is a chip with a "P" on it, that's the fuse? It reads open, infinite ohms, with the power connector removed.

So at this point...

1) need to replace the cable
2) need to replace the fuse

Correct?

Is it true that I need to open the display to replace the cable?
Any suggestions for a source for fuses? Part # , amp value, etc?

Thank you so much. This thread should be enshrined.

Kevin
 
Last edited:
Kevin117 said:
This thread is a sight for sore eyes (literally).

MBP i5 13, late 2011, water damaged, off eBay.

At this point I seem to have everything except trackpad (another thread, another day) and backlight working.

My motherboard is the version with the LVDC connector at a 45 degree angle. There are burned pins on the cable (on order), the connector side looks OK.

Nearby there is a chip with a "P" on it, that's the fuse? It reads open, infinite ohms, with the power connector removed.

So at this point...

1) need to replace the cable
2) need to replace the fuse

Correct?

Is it true that I need to open the display to replace the cable?
Any suggestions for a source for fuses? Part # , amp value, etc?

Thank you so much. This thread should be enshrined.

Kevin
Click to expand...

Zero ohms means the fuse is OK. It will measure infinity or Megaohms when it is blown.

You have to remove the glass from the display to replace the LVDS cable. That is a very delicate job and there are some video guides around. I personally do not use the suction cup method described in most videos because I find that when pulling the suction cup it is easy to break the glass. Rather, I use two sharp edged plastic pry tools (the kind you get with iPhone repair kits). I remove the display from the Macbook. I use a hot air solder rework tool with heat dialed down to 175C and air flow on max. Heat the border area near the starting point being careful not to damage the rubber gasket around the outside of the display. I start in the lower right edge since there is easier access to get the pry tool past the rubber and under the glass. I then work counter clockwise around the glass with cycles of heating, sliding the tools along under the glass, leapfrogging them over each other to maintain glass separation. Keep reheating ahead of the work site, slide a bit further. It takes lot's of patience. If you feel like you have to push too hard then stop and reheat some more. Take your time and move slowly. Eventually you will have all of the adhesive released and glass removed. You will need to replace the adhesive strips unless you want the glass falling out later. You can buy the strips from powerbookmedic for about 8 bucks.

It took me a while to do this consistently without breaking the glass. If you break it then there are replacement glass kits for about $25 on eBay.
 
Yes of course I meant infinity ohms. I posted before my morning coffee! (Zero vs infinity, none vs all, can't be more wrong than that!) I was correcting while you were composing your very informative reply. Thanks!

The fuse is the chip label with a "P" ?

It would be great if someone organized all the various model's photos from this thread with the fuses and backlight chips marked. As a reference catalog. I'd do it if I had the know-how.

Thanks again!
 
Kevin117 said:
Yes of course I meant infinity ohms. I posted before my morning coffee! (Zero vs infinity, none vs all, can't be more wrong than that!) I was correcting while you were composing your very informative reply. Thanks!

The fuse is the chip label with a "P" ?

It would be great if someone organized all the various model's photos from this thread with the fuses and backlight chips marked. As a reference catalog. I'd do it if I had the know-how.

Thanks again!
Click to expand...

No worries. So you will also be replacing the fuse then and, Yes, it is the one labeled with a P. I have often thought about creating a set of photos with common features identified but haven't made the time yet. Someday.... I will put them on the first post.
 
Dadioh said:
No worries. So you will also be replacing the fuse then and, Yes, it is the one labeled with a P. I have often thought about creating a set of photos with common features identified but haven't made the time yet. Someday.... I will put them on the first post.
Click to expand...

An atlas!

Any suggestions on where to buy fuses? Value? I thought I read 7 amps somewhere back there around page 17.
 
I mean a component level electronics supplier like Digikey.
What value and form factor are these fuses?

Thanks again.
 
Dadioh said:
I indicated fuse on attachment. The LVDS pins that carry backlight voltage are pins 21 and 22. Pin 30 is the far left pin in the photo. Count backwards from there.

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.

There is no way to bridge from the logic board to the LVDS cable connector since the pins are hidden once inserted into the connector.

My advice is to focus on obtaining one of the LVDS connectors from eBay and find someone who can replace it.
Click to expand...


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.

One last question . Which soldering tool is best value for money to do similar works ?
 
fmoras said:
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.

One last question . Which soldering tool is best value for money to do similar works ?
Click to expand...

If you are just starting out then a combination soldering iron and hot air rework would probably be the most economical choice. Also, I don't know if I could solder without a microscope.

I would suggest something along these lines. These are just examples I found with a quick search. Not endorsing either specific vendor or product.

http://www.ebay.ca/itm/Mt-220V-2in1...LH_DefaultDomain_0&hash=item19d7d907ce&_uhb=1


http://www.ebay.ca/itm/Stereo-Binoc...n_2&hash=item27cad1bd77&_uhb=1#ht_4136wt_1413
 
Dadioh said:
If you are just starting out then a combination soldering iron and hot air rework would probably be the most economical choice. Also, I don't know if I could solder without a microscope.

I would suggest something along these lines. These are just examples I found with a quick search. Not endorsing either specific vendor or product.

http://www.ebay.ca/itm/Mt-220V-2in1...LH_DefaultDomain_0&hash=item19d7d907ce&_uhb=1


http://www.ebay.ca/itm/Stereo-Binoc...n_2&hash=item27cad1bd77&_uhb=1#ht_4136wt_1413
Click to expand...

Thanks again for your infos. I already have a lab for pc repairs but know i want to extend it and buy some tools that can help me for this kind of soldering. The repair station that you send me looks to me very professional and very cheap. Sure microscope is a basic tool and i will order one. I can afford about 500-800 euros for tools. Maybe a basic bga station can help me ?:confused:

Also i have one more same logicboard for A1278 with another problem. It starts normally , when the circle down of apple logo turns , after 15 seconds fan is going to full speed and when osx starts and cursor appears for the first time after 1 sec BOOM... goes to sleep mode and backlight NEVER COME BACK.. logic board wake up , with torch again i can see everything but after 20 secs goes to sleep again. I already reset pram/nvram smc and all apple official combinations without results. i have changed the sleep/battery sensor without results i have checked the keyboard ribbon with other logic board and it's working. I also test macbook with another battery. Generally this logic board works normally until the full speed fan problem appears. I put out the logicboard to change thermal paste and when i opened again this problem appears. So I think that it's similar problem with the lvds connector or blown fuse of something or something like that.

I would appreciate if you can help me in this thread or link me to thread with this problem.:rolleyes:

Thank you again and again. :)
 
fmoras said:
Also i have one more same logicboard for A1278 with another problem. It starts normally , when the circle down of apple logo turns , after 15 seconds fan is going to full speed and when osx starts and cursor appears for the first time after 1 sec BOOM... goes to sleep mode and backlight NEVER COME BACK.. logic board wake up , with torch again i can see everything but after 20 secs goes to sleep again. I already reset pram/nvram smc and all apple official combinations without results. i have changed the sleep/battery sensor without results i have checked the keyboard ribbon with other logic board and it's working. I also test macbook with another battery. Generally this logic board works normally until the full speed fan problem appears. I put out the logicboard to change thermal paste and when i opened again this problem appears. So I think that it's similar problem with the lvds connector or blown fuse of something or something like that.

I would appreciate if you can help me in this thread or link me to thread with this problem.:rolleyes:

Thank you again and again. :)
Click to expand...

I would suggest running Apple Hardware Test (AHT). It is included on the application install DVD that came with the Macbook. Hold down the D key while booting and it will run the AHT. It may give you a failure code that identifies where to focus your efforts.
 
Dadioh said:
I would suggest running Apple Hardware Test (AHT). It is included on the application install DVD that came with the Macbook. Hold down the D key while booting and it will run the AHT. It may give you a failure code that identifies where to focus your efforts.
Click to expand...

sorry i forgot to mention it. i try to run AHT, but holding the d key while dvd is into drive , backlight is of again an go to sleep again , so i can't run AHT. The only way that backlight remains on is when i put install dvd an run a clean install until the last restart to boot into osx where again the sleep symptom appears again. I tested to a new hard drive cause i thought that maybe the problem was the hdd.
 
A1286 wont boot after changing

Hello All,

i need your help. I have a 1286 late 2011 Modell, without internal Backlight. I checked the Fuse with the P on it and it seems like that is blown.
After changing the Fuse, the book wont start. The Fuse is Blown again. It only charge the battery, no SMC Reset boot with Power botton on Board other Magsafe or anything will help.

Where can i do measurements ?
Hope you can help me to check which part could be dead and block starting the Machine.

Best regards Martin
 
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_9170_superimage.jpg


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.
 
Last edited:
Dadioh said:
I don't think so. I believe that was has happened is that the pad itself has completely corroded off the board. Circuit boards are made with layers of copper separated by an insulated material (FR4 is popular). If you dig through the FR4 you will expose the copper below the pad which is not the same signal.
Click to expand...


Took it to a guy near me that said he might be able to do some micro soldering. He agreed with me that it looked like that pad came off the hole through, and soldering a jumper from the one end to that hole through and voila! We now have a working macbook pro. Total cost of repairs $85. $50 for the soldering, $10 for the fuses, $20 for a magnifying glass(which I used), and $5 for the screwdriver. Done and done. Thanks for this thread and for the help it has provided my friend. I'm sure my friend will be extremely giddy when he finds out we rescued his mbp for such a reasonable price.
 
Lvds Connector Fries

Hi to all Guys,
My macbook pro took some milk last year...and the backlight goes wrong.
Yesterday i decided to go ahead lokking for some solutions.
I point a flash light directly to lcd and i could see the apple while os booting up and then the desktop.
So it means the lcd is working and the problem is around LVDS and other chip...right?

So i zoomed on my LVDS connector and i found...loosing some pins as in the picture.

IMG_3438.JPG

Is possible to do something without mb replacement, any suggestion?
 
Back again with meow questions

Not meow (cat related) "more". iPad has a mind of its own.

Here's the skinny....

Device: MacBook Pro A1278 i5 500gb (was 8G, but I downgraded to 4G)
Problem: No backlight, everything else seems to work fine now. I fixed a few other things like a bad trackpad cable, corrupt OSX.

Charges, runs for days on end, boots fine, audio, USB, wifi, all fine. Just no backlight.

The device was advertised as water damaged but there few visible signs. It must have been a very small quantity or was expertly cleaned. Just a few marks on the inner lower case near the power port.

What I did: After some research I found the fuse was blown and the LCD cable was burned on the motherboard side around pins 21-24 (common problem from reading this thread).

I changed the cable but in the process broke the glass (it was just in there too tight, even after using a heat gun for quite a while and suction cup. I replaced the glass and the cable.

As I was testing the fuse (which is bad) I accidentally shorted it out and the cable smoked again. So I'm back to square one.

BTW, I did not seal up the screen glass tightly yet, so there should be no trouble accessing the cable connector in there again.

The outstanding issue, who's cause is one I hope you're familiar with is, is... why does the cable burns up at the same point pins 21-24 area?

Is this a LED short or a problem with the motherboard side of the 30 pin connector? BTW, I have a spare identical machine which I could use for parts. It has a completely dead motherboard, severe water corrosion, but the lid and LCD look fine. And the LCD fuse is intact (zero ohms). If I was confident the smoke and sparks were caused on the LCD side I'd swap the lids out.

Questions: does this all sound familiar to you? What is the typical reason/s?

Thank you very kindly,
Kevin
 
Last edited:
No waking up from sleep .

Dadioh said:
IMPORTANT NOTE: Further in this thread you will read that this part is a high frequency capacitor. IT IS NOT A FUSE!!! PLEASE do not go about replacing this part with anything other than a capacitor. READ CAREFULLY the whole thread before messing around with component substitutions.


Original post
----------------------------
I obtained a Macbook Pro 13 unibody with non functioning display (everything else works). I took it apart ad discovered that the LVDS cable end was completely destroyed. I ordered a replacement display assembly (complete with LVDS cable). I now have an image but no backlight.

Upon close examination of the components surrounding the LVDS connector I notice I have a component missing compared to a detailed photo of the same motherboard that I found on the net. I am not sure if this component might be a fuse that has been removed. I am trying to find someone who has one of these logic boards accessable that can identify what this part is supposed to be.


Update: There are many many more tips and info in this thread to help you with troubleshooting backlight issues on Macbook Unibody.

In particular the WLED driver should be checked for failure. A useful method is to test the resistance (impedance) from each pin of the WLED driver device to ground. Typical values are shown below.

Make sure power is removed from board before testing resistance. Unplug battery or battery connector.

Macbook Pro 13"
Device LP8543 Pin 1 is lower left and counts counter clockwise around the device.
Pin Resistance to ground
1 0
2 1K
3 124K
4 100K
5 0
6 >1M not connected
7 >1M
8 19K
9 0
10 not connected
11 21K
12 >1M
13 >1M
14 >1M
15 0
16 >1M
17 >1M
18 >1M
19 not connected
20 0
21 >1M
22 203K
23 400K
24 290K


On Macbook 13 unibody aluminum non-Pro
Device APP001A

1 3.8M
2 100
3 9.9M
4 46K
5 100K
6 100K
7 >10M
8 49K
9 69K
10 >1M
11 >1M
12 >1M
13 0
14 >1M
15 >1M
16 2.8M
17 10K
18 15K
19 34K
20 30K


If your WLED driver is blown you may measure zero or low resistance on some of the pins that are not supposed to be ground.
Click to expand...

Hi I am sure you guys can help me ? I am sorry to jack this thread,but I have a issue with a a1278 k6 .
Basically it works fine apart from when you close the lid and open it the screen does not come back on no backlight or image I have even looked with a light .

When cleaning it I noticed a problem with the q4300 I have looked on the schematic found the part and I know it part of the firewire protection curcuit as far I can make out ?
Anyway I had the part an fixed the corroded pads replaced it and fitted a new resistor from a spare board so tho parts are good .

What my question is what page is the power up for the lid on the schematic ?
Please if some one could point me onto that page I mite stand a chance of fixing it .
Is it part of power sequencing HELP lol ?

I"m a newbe so please be kind I have a little electronic skill .
 
macbook air 13" mid 2011

I know this thread is about the macbook pro, but could my macbook air getting fixed the same way?

Screen is working but backlight isn't after some wine spill.

Took this picture.

351buci.jpg
 
Your part labeled "fuse?" looks exactly like my fuse on a MacBook Pro 13 i5 late 2011. MD313LL/A. Although my fuse is located elsewhere. The boards are different.

I'd try measuring resistance across it WITH THE POWER CORD DSCONNECTED AND THE BATTERY DISCONNECTED.

Zero ohms means it's good
Infinity ohms (or anything but zero) means it's blown.
 
I'm looking for my fuse on MB 820-2533 B of my macbook 2.53 nid 2009 but i can't find...can anyone can help me???

Thanks.

fab
 
Kevin117 said:
Your part labeled "fuse?" looks exactly like my fuse on a MacBook Pro 13 i5 late 2011. MD313LL/A. Although my fuse is located elsewhere. The boards are different.

I'd try measuring resistance across it WITH THE POWER CORD DSCONNECTED AND THE BATTERY DISCONNECTED.

Zero ohms means it's good
Infinity ohms (or anything but zero) means it's blown.
Click to expand...

Okey, this fuse is blown, so need to get replaced.

Also saw the LVDS cable, looks like it is burned on the right side.

2uh63nq.jpg

jl5n3t.jpg
 
Hi,

I have spilled my macbook pro 15" early 2011 with little water. On the Logic Board there is no damage. But if turn on only black screen and the fan speeds up to the max after 30 seconds. No chime, no noise from slot in. I found 4 fuses on this Logic board but all fuses are ok. Topcase and Keyboard is also ok, tried with different Mainboard. Battery is loading and it starts also from battery. If plug in magsafe it turns on automatically no need to press on/off button. No connectors fried. Ideas will be appreciated :)
 
MBP 13" 2.26GHz

Hello All!
I had a post earlier about my liquid spilled A1278 MBP.
I managed to get some parts from a physically damaged board (smashed in the middle by a kid), it was fully functional before the rampage...
I replaced a FET(has to do something with power-on, on my board is was replaced with an other part), a diode, a capacitor, a fuse, and the WLED driver.
after first attemt i got backlight, but only in the corners, very dim.
Switched the laptop off, contact cleaned the LVDS socket, and voila, i got backlight.
The only problem is, that it began to fade in and out(full on full off) in about 25 seconds after the start. The dim in and out is getting quicker and quicker, and then it swtches off the backlight.
if you restart the laptop it has no backlight.
The only solution to get it back, to remove the battery, remove LVDS, contact clean the LVDS socket and the LVDS cable, pop it back, battery back, and switch it on.
the problem repeats itself, so 20-25 secs, dimming in-out, then no backlight.
i dont think it's the LVDS socket(but can be, who knows), looks like more some thermal heat-up issue.
i havent changed the 638Z backlight FET, can it be the problem? if yes, where is it?
what should i measure? where to start to have the solution?
greetings
Zsolt

photo3bkp.jpg

photo2pk.jpg

photo1klb.jpg
 
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