MacBook Pro Unibody - No Backlight - Logic Board Question

[docal97]

Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_2_1 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8C148 Safari/6533.18.5)

I agree. People Frequently form judgements too quickly. Good luck in your search. Did u look at the high res pics on ifixit.com?

[lostkawz21]

Dadioh, thanks for posting this and being so helpful. I wish i had researched this before i sold my mbp. thanks to everyone else on here as well for all the info and help.

[Dadioh]

Originally Posted by lostkawz21

Dadioh, thanks for posting this and being so helpful. I wish i had researched this before i sold my mbp. thanks to everyone else on here as well for all the info and help.

You are welcome. Good to hear of more than a few logic boards being saved from the land fill

[bobthebob]

hey all - looking for similar resources for my late 2009 MBP.

liquid spill about a week ago caused instant screen blackout and power off. spill was in the upper right corner - so near the power button.

disassembling and then drying and cleaning with alcohol have not resolved the issue - two days ago i put it together and when the power button was pressed the fans started up at very high RPM.

disassembled and then recleaned with alcohol - waited till tonight to put it back together and now power button has no effect at all.

green light is on on the magsafe connector.

tried all this without the battery first and then with. can't remember if fans only worked when battery was in and now am at my girlfriends so i can't check.

anyway - i'd love a schematic of the logic board so i can check and see if this might be a simple blown fuse (crossed fingers!).

if anyone has any advice at all i'd be really grateful - this is one of the only places on the web that i've found any detailed info on troubleshooting logic board circuits.

cheers,
b

[lostkawz21]

Originally Posted by componentfix

OK for all the people with no backlight on a macbook pro 15" unibody.

first of all thanks to the man with the schematic....
I take it you have checked the flurecent and inverter allready and both are ok.
on the logic board there is a fuse that supply's the voltage/ currant to the backlight circuit...its F9800.Its located on the board near the botom of the left fan on the component side of the board.(same side that has the cpu and gpu on it).

the fuse is a smd and its white with just a dot on it.get your multimeter and if its open circuit thats you problem.
got mine fixed today...

If you need a hand then drop me a line and i will try to see what i can do...

Had to share this as it took me a good day to put right,,,

good luck.

componentfix

hello, i have another MBP that i am having same issue with. no backlight. i checked the F9800 fuse and its has continuity. can anyone tell me how to check the QFN on here. It appears to be a 21 pin QFN versus the 24 pin QFN mentioned on the 13". Any help would be greatly appreciated.

[Dadioh]

Originally Posted by lostkawz21

hello, i have another MBP that i am having same issue with. no backlight. i checked the F9800 fuse and its has continuity. can anyone tell me how to check the QFN on here. It appears to be a 21 pin QFN versus the 24 pin QFN mentioned on the 13". Any help would be greatly appreciated.

Maybe a 20 pin QFN? The number of pins should be divisible by 4 as suggested by the Q in QFN unless you count the thermal pad under the chip. That could be pin 21.

Seriously though, you are going to need to find a schematic and then ohm out all of the QFN pins and determine if some of the pins that are not supposed to be ground are now ground. The blown ones that I have had all had some sort of internal short to ground.

I also had one that had a resistor on the enable pin that had blown open. Much easier fix than the QFN.

[Nathn G.]

Hi guys,

My name is Nathan, and I have had some issues much like the ones described.

I picked up a used 15.4" MacBook Pro Unibody model 1286 on eBay in December. The video out worked fine, but the monitor didn't turn on...so I thought. After replacing parts and much trial and error, I discovered that the original LVDS cable and LCD LED screen were in working order--I could hold a flashlight to the screen and see the desktop and interact with it.

So I'm currently pricing repair options. I was wondering if there was anyone on this board who could repair the board in a cost effective and timely manner.

I saw some repair services on eBay, but I'm still evaluating whether or not to go that route.

Mods: If I've posted in the wrong place, feel free to move this post wherever it should be.

Thanks much guys!

Best Regards,
Nathan G.

[Red.Fury]

Hey guys. Ok. I have a macbook a1181. I dropped it on the floor. and i came up with two possible issues. the inverter and the backlight. I have replaced the inverter and still nothing. now I have to replace the backlight. My dad has completely taken apart my mac. but we cannot seem to find where the backlight lamp or bulb is located. if anyone can find this out for me. i couldn't thank you enough.! I have a very dimmed screen. Hard to see. When i replaced the inverter, there was a slight increase in brightness!

[Dadioh]

Originally Posted by Red.Fury

Hey guys. Ok. I have a macbook a1181. I dropped it on the floor. and i came up with two possible issues. the inverter and the backlight. I have replaced the inverter and still nothing. now I have to replace the backlight. My dad has completely taken apart my mac. but we cannot seem to find where the backlight lamp or bulb is located. if anyone can find this out for me. i couldn't thank you enough.! I have a very dimmed screen. Hard to see. When i replaced the inverter, there was a slight increase in brightness!

The lamp is embedded within the LCD panel at the bottom. Replacing it would be very delicate work and probably not worth it since you can find brand new LCD panels for less than $100 on eBay. If your inverter board is good then just replace the panel. Not too difficult a repair if you take your time and follow some guides.

[Red.Fury]

Hey, would you have an image of where its located, because yeah i will probably buy the lcd screen but i want to try the bulb first

[macbookpro1]

[QUOTE=componentfix;11152475]OK for all the people with no backlight on a macbook pro 15" unibody.
can you contact me at iphonereal1@hotmail.com

[lostkawz21]

Originally Posted by Dadioh

Maybe a 20 pin QFN? The number of pins should be divisible by 4 as suggested by the Q in QFN unless you count the thermal pad under the chip. That could be pin 21.

Seriously though, you are going to need to find a schematic and then ohm out all of the QFN pins and determine if some of the pins that are not supposed to be ground are now ground. The blown ones that I have had all had some sort of internal short to ground.

I also had one that had a resistor on the enable pin that had blown open. Much easier fix than the QFN.

Dadioh, the schematic posted on here is for my macbook. i checked all the resistors and they are all ok. i checked the pins on the QFN and i found that pin 16 and 17 have continuity. I don't think that is correct. can you verify this
?

[Dadioh]

Originally Posted by lostkawz21

Dadioh, the schematic posted on here is for my macbook. i checked all the resistors and they are all ok. i checked the pins on the QFN and i found that pin 16 and 17 have continuity. I don't think that is correct. can you verify this
?

When you say pins 16 and 17 have continuity do you mean they are shorted to ground? If so, that is definitely not right. Pins 12, 13, 14, 16, 17, and 18 are the 6 return lines from the LED drivers in the display. They come from the display and pass through 10.2ohm current limiting resistors and then into the pins on the QFN. I can't recall what their impedance to ground should be but it should not be zero. Is this a liquid damaged unit? Maybe there is residue on those pins (long shot)? Otherwise they may be internally shorted in the QFN and you will need to replace it.

[thxkbye]

I have a 2009 17 inch unibody that had a liquid spill. I took the machine apart and cleaned the board with distilled water and a toothbrush. I allowed it to dry for days and put it back together. The machine boots and everthing works fine except the backlight on the LCD. I can see with a strong light.

I am in school and spent so much on this machine, I can't believe how stupid I was to spill on it. With my current tuition and expenses there is no way I can get it repaired professionally right now. Apple wants far too much money for repair and I just cant do it. I have been reading these forums and I am encouraged by what I see here but this is far beyond my capabilities. Any advice would be so much appreciated.

[Dadioh]

Originally Posted by thxkbye

I have a 2009 17 inch unibody that had a liquid spill. I took the machine apart and cleaned the board with distilled water and a toothbrush. I allowed it to dry for days and put it back together. The machine boots and everthing works fine except the backlight on the LCD. I can see with a strong light.

I am in school and spent so much on this machine, I can't believe how stupid I was to spill on it. With my current tuition and expenses there is no way I can get it repaired professionally right now. Apple wants far too much money for repair and I just cant do it. I have been reading these forums and I am encouraged by what I see here but this is far beyond my capabilities. Any advice would be so much appreciated.

Since you can see the dark image that means that the LVDS data cable is OK and sending the signals to the display. It is the backlight that is out. I don't have access to a schematic for the 17" unibody but I suspect it is very similar to the 13 and 15. There is a good chance that it is just a fuse that is blown. This fuse protects the circuit that provides 12V to the backlight driver device. In the MBP 13" it is a 2A fuse and is beige with a white dot on the top. You could look around with a magnifying glass (it is an 0402 package so very tiny) and see if you spot one near your LVDS connector. Then get an ohmeter and test to see if that fuse is blown open. If you are lucky it is just the fuse. If you are unlucky it could be the driver chip itself and that is not an easy fix.

Good luck. Let us know how it goes.

[thxkbye]

Ok, so I looked at the board near the LVDS cable and I cannot find anything resembling the photo... The connector is angled in the 17inch unibody. If anyone out there has a detailed photo of the board or a document that shows where the fuse is I would really appreciate it. If I can identify it I will test it or possibly find someone local with excellent soldering experience to try and help me out. I would also be willing to remove the board and mail it to someone for repair if possible. Just running out of options here and spending 500+ is not something I can do anytime soon.

My camera is not that good at taking photos close up but I found this on the net.


I know im an idiot for what happened but at least it looks like there may be a way out. Thanks again.

[Dadioh]

Originally Posted by thxkbye

Ok, so I looked at the board near the LVDS cable and I cannot find anything resembling the photo... The connector is angled in the 17inch unibody. If anyone out there has a detailed photo of the board or a document that shows where the fuse is I would really appreciate it. If I can identify it I will test it or possibly find someone local with excellent soldering experience to try and help me out. I would also be willing to remove the board and mail it to someone for repair if possible. Just running out of options here and spending 500+ is not something I can do anytime soon.

My camera is not that good at taking photos close up but I found this on the net.

I know im an idiot for what happened but at least it looks like there may be a way out. Thanks again.

It is entirely possible that the fuse is on the back of the circuit board. I assume that when you say you have cleaned the logic board that you removed it and cleaned the back as well? If not you should do that. If so, then you know how to remove it and then, if you can get a detailed photo of the back at high res I can see if I can help you spot the fuse. Same for the front since the image doesn't have enough resolution to zoom in on small parts. I know you said your camera can't do it but maybe you could borrow one?

[thxkbye]

Ok so I took some photos, front and back of the board. Please let me know if you see what could be the fuse, I have a multimeter but I will need to learn to use it right to check. Thank you for your help!
back

front

[Dadioh]

OK. I spotted the fuse. Resolution is not "quite" good enough to see but it looks like it has a white dot on the top and the label looks like F9500 (or something like that). Take your multimeter and set it to measure resistance. Put the leads across that component and see what the resistance is. Depending on the quality of your meter it will read something like 1 to 10 ohms. If it measures a big number, like megaohms then the fuse is blown.

I have also labeled the device that drives the voltage to the backlight. It is possible that this is blown if the fuse is showing as good.

Remember to do all your measurements with the battery disconnected.

Good luck and report back,

[thxkbye]

Dadioh, Thank you so much for the assistance. Sorry about the pic quality. Just so you know I am pretty sure what looks like a white dot is actually the letter "p". Does it matter? Is this the fuse? Here is a closer look...

[Dadioh]

Yup. Pretty sure that is the fuse. To answer it beyond a shadow of a doubt, take you rmeter and measure resistance between the 2 legs shown below. It should be 300 kohm.

What's the resistance across the fuse showing?

[thxkbye]

I am going to be out of town for the next few days. so the soonest I can check is on Sunday night. I will get back to you and post the readings. Thanks again for your help!

[cherokeejerod]

Hi all, I'm new to forum, lots of good info here! Waiting for response from thxkbye on his board's readings. I have a 15" mac pro unibody mid 2010 i5 board(820-2850-A) with no LED backlight issue also. I can see a faint image on the screen and the external moniter worked if I held the wire just right. Wire might be bad. This board has no markings or lettering to help find fuses etc. I've attached a pic to help find out if this is the right fuse and to maybe help others locate it on theirs. I have 298k ohm as marked on a component marked 638Z, and no continuity on what I think is the fuse.
The pic is from the component side of the board, under the left speaker, between the USB port and the fan, near the inboard mounting screw hole.
Any help would be much appreciated. Thanks, cherokee.

[Dadioh]

Originally Posted by cherokeejerod

Hi all, I'm new to forum, lots of good info here! Waiting for response from thxkbye on his board's readings. I have a 15" mac pro unibody mid 2010 i5 board(820-2850-A) with no LED backlight issue also. I can see a faint image on the screen and the external moniter worked if I held the wire just right. Wire might be bad. This board has no markings or lettering to help find fuses etc. I've attached a pic to help find out if this is the right fuse and to maybe help others locate it on theirs. I have 298k ohm as marked on a component marked 638Z, and no continuity on what I think is the fuse.
The pic is from the component side of the board, under the left speaker, between the USB port and the fan, near the inboard mounting screw hole.
Any help would be much appreciated. Thanks, cherokee.

That would be the fuse with the dot on the top. It is probably a 2A fuse so get a new one and replace it. Make sure you have cleaned up the rest of the circuit board first. The fuse blew for a reason... probably the presence of liquid but make sure everything is clean now. 99% pure isopropyl alcohol and a toothbrush for the win....

[cherokeejerod]

Thanks for the fast reply! This mac didn't have a spill, but someone tried to break it over their leg and smashed it pretty good. It may have more issues than the fuse. I got it for nothing and have replaced the entire case, LED screen, etc. I have about $400 in it so far, and hope to get it working again. Thanks for your help, I might be another step closer to reviving this one. Man is that fuse small!!! I'll have to read up on trying to replace that.