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MacBook Pro Unibody - No Backlight - Logic Board Question

kilgrinus said:
Lots of great info on this thread and now I'm hoping you guys can help me out. I have a 2009 MBP 13 with no backlight. I have replaced the fuse, WLED driver,LCD, and LVDS cable but still no backlight. I have 3 volts on enable pin (4 of WLED) and 12 volts on both sides of the boost diode.
Click to expand...

12v on the output of the boost diode means the WLED driver is not boosting. With power disconnected from the board disconnect the lvds cable and see what the resistance to ground is on the backlight pins of the connector. Maybe there is a short in the lvds connector on the logic board.
 
Checked

None of the backlight pins were short to ground. I also checked the resistance on the WLED driver and found pins 8 and pin 11 were about half of what they were supposed to be but not sure what it means.

Dadioh said:
12v on the output of the boost diode means the WLED driver is not boosting. With power disconnected from the board disconnect the lvds cable and see what the resistance to ground is on the backlight pins of the connector. Maybe there is a short in the lvds connector on the logic board.
Click to expand...
 
kilgrinus said:
None of the backlight pins were short to ground. I also checked the resistance on the WLED driver and found pins 8 and pin 11 were about half of what they were supposed to be but not sure what it means.
Click to expand...

This was my first time working on such small circuitry. Could it be that I damaged the WLED driver upon install. I purchased this unit off eBay with liquid damage and after my repairs it is in the same condition.
 
Any recommendations for someone to do this repair in the SouthEast US? .

Macbook Unibody non-pro a1278 and the backlight isn’t workingI don’t have a voltmeter to check if it’s a faulty WLED driver. Please let me know and pricing. Thank you.
 
MBP Mid-2010 A1278 - Spill, No Backlight

Hi All:

I purchased locally and got everything operating except backlight. Fuse was blown and replaced. Now getting 39 volts at diode instead of 0... Yes, 39 volts. No damage to LVDS pins and no obvious burns or other anomolies from visual inspection. I am guessing maybe voltage divider? I still need to measure LVDS cable. Anything else? Can someone point to which resisters to measure for voltage divider if that is logical point to examine?

Also, I noticed while soldering the fuse some sort of residue in several small areas. I decided to do a teardown and board cleaning. After assembly, with the bottom cover on, fan will go to full speed while booting and wifi will disappear once booted and running for a few minutes. All is fine when I boot without the cover. I am guessing a short somewhere between logic board and bottom cover. Where on the logic board is the wifi? Anyone else experience the fan and wifi issue?

I have repaired the fan and wifi issue. Removed/re-installed logic board and now problem is gone. Unfortunately, not too sure why...:confused:
Thank you!

Jeff
 
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i have a a1278 late 2011 and my headsed connector stuck inside the jack i opened the it and put it out everything was ok but when i put in the cover i notice a smell of burn when i open it back again i notice a line open just near the display connector and i don't have video how may i fix it:confused :
 
Replaced Backlight Blown Fuse

Hello Dadioh,

Thank you very much for your information.
I was able to put a new fuse using some computer thread cable which made the soldering job much easier than replacing the old blown fuse.

Now the Backlight is working perfectly!

I just want to point that I as many others appreciate your dedication to this forum.

regards,






Dadioh said:
Most likely you have blown the fuse. See the picture in the post by Seahawk up a little further in this thread. If that is the same board you have then the fuse is the component with the "P" on it. Luckily for 2011 owners Apple changed from a tiny 0402 size fuse to a less tiny 0603 fuse which is a little easier to work with.
Click to expand...
 
mayor said:
Hello Dadioh,

Thank you very much for your information.
I was able to put a new fuse using some computer thread cable which made the soldering job much easier than replacing the old blown fuse.

Now the Backlight is working perfectly!

I just want to point that I as many others appreciate your dedication to this forum.

regards,
Click to expand...

You are welcome. Just be aware that since you don't have a fuse now that if you have a liquid spill that much more extensive damage can happen when the liquid hits the backlight circuit. You should consider replacing the fuse at the next opportunity.
 
macbook pro 17" i7 1297

Hi I am new to this forum and would like to thank Dadioh for your help in advance. I received a 17" macbook pro 1297 with liquid damage. I have read the forum and WOW there is so much info! I cleaned the board using contact cleaner and qtips. There was no corrosion or signs of water on the logic board. It seemed pretty clean but I cleaned it anyways. The units powers on fine and chimes, but there is no backlight. I also checked using a flashlight and could see very dim images. I also checked the white fuse close to the mag safe input on the logic board and it checks out at 12V. What other fuses should I check and what should I look for in order to start diagnostic these issues?

-Thanks
 
elitetek said:
Hi I am new to this forum and would like to thank Dadioh for your help in advance. I received a 17" macbook pro 1297 with liquid damage. I have read the forum and WOW there is so much info! I cleaned the board using contact cleaner and qtips. There was no corrosion or signs of water on the logic board. It seemed pretty clean but I cleaned it anyways. The units powers on fine and chimes, but there is no backlight. I also checked using a flashlight and could see very dim images. I also checked the white fuse close to the mag safe input on the logic board and it checks out at 12V. What other fuses should I check and what should I look for in order to start diagnostic these issues?

-Thanks
Click to expand...

I can't remember if anyone has posted a photo of the 17" fuse location. Do a search in the thread. If not, post as clear a closeup pic as you can manage of the front and back of the logic board near the lvds connector and we can help you spot it.
 
I will upload some pictures. I just wanted to add, once you press the power button I can hear a very low "buzz" sound for about once second, when the back light is trying to turn on.
 
Macbook Pro 17" A1297 820-2914 - HI RES PICTURES

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Thanks Dadioh. Now what is the correct value that should be showing? I tested it and no load value was shown. should I have the unit powered on to check? would the buzzing down during post refer to a failed screen or fuse?
 
elitetek said:
Thanks Dadioh. Now what is the correct value that should be showing? I tested it and no load value was shown. should I have the unit powered on to check? would the buzzing down during post refer to a failed screen or fuse?
Click to expand...

Measure it with power removed and multimeter on resistance. Not sure if you have an analog meter or digital but it should read close to 0 ohms. If it is blown then it will measure in megaohms.
 
Thanks Dadioh. I am not getting any reading on the Fuse. Now the question is how can I identify the SMD Fuse part number or how many AMPS or Volts needed?
 
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MRrook said:
Any recommendations for someone to do this repair in the SouthEast US? .

Macbook Unibody non-pro a1278 and the backlight isn’t workingI don’t have a voltmeter to check if it’s a faulty WLED driver. Please let me know and pricing. Thank you.
Click to expand...

Find a local shop and look for proof of soldering skills. There have to be at least five people in every city that can handle these issues. You just have to find them.

elitetek said:
Thanks Dadioh. I am not getting any reading on the Fuse. Now the question is how can I identify the SMD Fuse part number or how many AMPS or Volts needed?
Click to expand...

I use 24v/1 amp in a 0603 package for those, usually bourns brand. I forget what the original is. None have blown, with full brightness on flashing screens. I believe the original is a higher voltage/amperage. I haven't had a problem with these.
 
does 12v on the top part of the fuse and 0v on the bottom side mean that the fuse is blown and most likely everything is still good. This is for a 2009 A1278 macbook pro.
 
Could I just solder a very thin wire on both sides of the fuse to test the fuse? what would you guys recommend.
 
jamesnh said:
does 12v on the top part of the fuse and 0v on the bottom side mean that the fuse is blown and most likely everything is still good. This is for a 2009 A1278 macbook pro.
Click to expand...

That means the fuse is blown. It would be 12V on both sides if the fuse is good.

----------
elitetek said:
Could I just solder a very thin wire on both sides of the fuse to test the fuse? what would you guys recommend.
Click to expand...

That is risky. If the failure condition that caused the fuse to blow is still present then the wire will allow significant current to flow and may smoke components. The fuse is there to protect parts.

As Dirty Harry said... "You gotta ask yourself one question.... Are you feelin' lucky?" :)
 
Good news! I found a place in Toronto where they do these these type of delicate repairs. I will left you guys know how it goes. Thank you again for all your help.

Dadioh do you accept repairs ?
 
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Late 2008 Macbook Unibody (not pro) 13"

I am experiencing the same issue with a non-existent backlight but since I don't have a Macbook Pro as the other posters, the shot of the logic board doesn't help me. So I can't find the fuse that needs to be replaced. Does anyone have either a description of its location or, better yet, a photo?
 
Does anyone have the schematics for a MacBook Pro 15.4" A1286 early 2011?

Thanks
 
jghowes said:
I am experiencing the same issue with a non-existent backlight but since I don't have a Macbook Pro as the other posters, the shot of the logic board doesn't help me. So I can't find the fuse that needs to be replaced. Does anyone have either a description of its location or, better yet, a photo?
Click to expand...

I am pretty sure the fuse location for the 2008 aluminum unibody 13" is in the thread. Do a search and let me know if you can't find it. The fuse is on the back side of the board near the DCin connector.
 
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