MacBook Pro Unibody - No Backlight - Logic Board Question

[joccolai]

MBP 17" A1297, locate WLED driver

Hi,

I have a MBP 17", (logic board 820-2914A), with small liquid damage. Everything works great, except for the backlight. Have tested both a new LCD-panel, and the LVDS-cable. No luck. So I am guessing I have to look at the WLED and its respective fuse.

I have read the whole thread here on the forum, and also eye-searched my whole MLB, but cannot seem to find out where the wled driver or the fuse is. Is it so that the WLED driver is located near the LVDS-connector, or can it be anywhere on the board?

Anyway, I am attaching a picture of an identical board, and praying someone can point me in the right direction here. (pics are not of the actual board, but another, identical one. Should not make any difference)

http://photobucket.com/mbp17a1297

Thanks allot

 

[3verve]

Which 2A 0402 Fast Acting fuse to buy?

Hi Guys

Thanks for a very informative thread. I was able to find the 2A 0402 fuse (what a nightmare but led light and a magnifying glass finally did the work) but the issue is which one to get??

Mine is Alu Unibody 15.4" Mid-2010 MacBook Pro A1286.

There are 2 variations one can get. They are as follows:

24VDC 2A 0402 Fast Acting Fuse:
http://uk.rs-online.com/web/p/non-resettable-surface-mount-fuses/6924968/

32VDC 2A 0402 Fast Acting Fuse:
http://uk.rs-online.com/web/p/non-resettable-surface-mount-fuses/6924971/

These are produced by Bourns with 'F' on the fuse but the 24VDC and 32VDC have different sizes: 24VDC is 1mm length versus 32VDC 1.6mm length plus variances in thickness and width as well! There are other Fast Acting 2A 0402 fuses available too in which 24VDC and 32VDC are the same size! This is confusing

Since WLED output is 27v for the backlight, which one is the right spec? My friend, who is doing the replacement work for me, says that it is possible from 24v to be stepped up to 27v so 24VDC fuse 'could' be fine but has asked me to get confirmation. He is going to measure the existing fuse but won't be able to tell if it is 24VDC or 32VDC.

And I have not been able to find any fuses with a white dot on them, only 'F' is on the Bourn fuses.

Please can you someone confirm for definite which is the right fuse to go for: 24VDC or 32VDC?

Here is the list of all the 2A 0402 fuses I can select from (rs website in UK is next day delivery whereas digikey gets shipped from USA so takes a while to get to UK but has a bigger range of 2A 0402 Fast Acting fuses:
http://www.digikey.co.uk/scripts/dksearch/dksus.dll?vendor=0&keywords=2A+0402+fast+acting (need to apply filter)


Also, can anyone point me to where I can get hold if this 638Z capacitor (with 6 legs)? 2 sets of legs give me 3V as they should, whereas 1 set doesn't. I want to get the fuse changed first and then test this 638Z chip/fuse/?. I've also ordered a few LP8545SQ WLED drivers, along with new LVSD Connector (3 burnt pins!) and LVSD Wire (burnt pins have caused a short somewhere between the corresponding pins on the wire).

Many thanks in advance
V

 

[3verve]

aaah, so it is a fuse afterall --- 638Z!

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?

On mine, its 0 on the first set of legs, and 300 on each of the 2 sets. 2A 0402 is reading 0 on voltage, ohms etc ...

 

[3verve]

These are the pics of my WLED, 638Z fuse, and LVSD Connector.

If there is schematics available for my Core i5 Mid-2010 15.4", that would be great because only the MB is with my friend in UK (he has a full lab) and with schematics he can test everything. Please let me know.

In the 638Z fuse picture, pair of pins in rectangle within the full fuse have no/0 resistance whereas the top two pairs are giving 300K ohms. or 0.3 iirc. 2A 0402 Fuse had no resistance on any of the multimeter settings. These are the tests I have done, and he can do them better with much higher spec equipment, just need a write up on what exactly he needs to do and he will do this and report back and I'll post here.

If there are any other tests (he can't turn on the board) as rest of the laptop is with me in Asia, please let me know. Also, what the measurements of the LP8545SQ WLED Driver 24 pins should be, that would be great. Schematics would be ideal, he can test the whole board with it.

Thank you so much. You guys, esp Mr Diadoh, have got me this far, just need a bit more info to get it working.

 

[Dadioh]

Hi Guys

Thanks for a very informative thread. I was able to find the 2A 0402 fuse (what a nightmare but led light and a magnifying glass finally did the work) but the issue is which one to get??

Mine is Alu Unibody 15.4" Mid-2010 MacBook Pro A1286.

There are 2 variations one can get. They are as follows:

24VDC 2A 0402 Fast Acting Fuse:
http://uk.rs-online.com/web/p/non-resettable-surface-mount-fuses/6924968/

32VDC 2A 0402 Fast Acting Fuse:
http://uk.rs-online.com/web/p/non-resettable-surface-mount-fuses/6924971/

These are produced by Bourns with 'F' on the fuse but the 24VDC and 32VDC have different sizes: 24VDC is 1mm length versus 32VDC 1.6mm length plus variances in thickness and width as well! There are other Fast Acting 2A 0402 fuses available too in which 24VDC and 32VDC are the same size! This is confusing

Since WLED output is 27v for the backlight, which one is the right spec? My friend, who is doing the replacement work for me, says that it is possible from 24v to be stepped up to 27v so 24VDC fuse 'could' be fine but has asked me to get confirmation. He is going to measure the existing fuse but won't be able to tell if it is 24VDC or 32VDC.

And I have not been able to find any fuses with a white dot on them, only 'F' is on the Bourn fuses.

Please can you someone confirm for definite which is the right fuse to go for: 24VDC or 32VDC?

Here is the list of all the 2A 0402 fuses I can select from (rs website in UK is next day delivery whereas digikey gets shipped from USA so takes a while to get to UK but has a bigger range of 2A 0402 Fast Acting fuses:
http://www.digikey.co.uk/scripts/dksearch/dksus.dll?vendor=0&keywords=2A+0402+fast+acting (need to apply filter)


Also, can anyone point me to where I can get hold if this 638Z capacitor (with 6 legs)? 2 sets of legs give me 3V as they should, whereas 1 set doesn't. I want to get the fuse changed first and then test this 638Z chip/fuse/?. I've also ordered a few LP8545SQ WLED drivers, along with new LVSD Connector (3 burnt pins!) and LVSD Wire (burnt pins have caused a short somewhere between the corresponding pins on the wire).

Many thanks in advance
V

Just have a quick moment so can't read through your whole post but will do it later. However, just a quick answer on the fuse. The fuse is on a 12V circuit not on the 27V for the backlight. So it is only handling 12V prior to the 638Z package which is a pair of FET's in a package. I have never seen the 638Z blow so I am guessing it will be your fuse.

As far as fuse selection as long as it is an 0402 package size it should fit.

 

[Dadioh]

Hi,

I have a MBP 17", (logic board 820-2914A), with small liquid damage. Everything works great, except for the backlight. Have tested both a new LCD-panel, and the LVDS-cable. No luck. So I am guessing I have to look at the WLED and its respective fuse.

I have read the whole thread here on the forum, and also eye-searched my whole MLB, but cannot seem to find out where the wled driver or the fuse is. Is it so that the WLED driver is located near the LVDS-connector, or can it be anywhere on the board?

Anyway, I am attaching a picture of an identical board, and praying someone can point me in the right direction here. (pics are not of the actual board, but another, identical one. Should not make any difference)

http://photobucket.com/mbp17a1297

Thanks allot

I think it is the device shown in my picture but to be sure can you read the part number off the top for me?

Also, can you get closeups of the front and back at this location (beside the LVDS connector) and around this device on the back so I can help you find the fuse.

 

[insiderla]

Backlight damage A1278

Hi guys,

I've got a big problem with my MBP A1278 and I hope you can help me
My Macbook fell on the floor and since this the backlight does not work anymore... I changed the LCD cable and the display already, but it was not successful.. I read about the fuse on the backside of the logicboard (the fuse with the white point) and checked this with a multimeter and it whistled.

What can I do? Please help me..

Best wishes

Michael

 

[3verve]

Just have a quick moment so can't read through your whole post but will do it later. However, just a quick answer on the fuse. The fuse is on a 12V circuit not on the 27V for the backlight. So it is only handling 12V prior to the 638Z package which is a pair of FET's in a package. I have never seen the 638Z blow so I am guessing it will be your fuse.

As far as fuse selection as long as it is an 0402 package size it should fit.

Thanks Dadioh for your response. I'll wait for your detailed response re WLED testing etc. I've ordered 24VDC 2A 0402 fuse instead of 32VDC and LVSD Connector so he'll replace those first.

 

[wedgeman]

I've got a 15" Macbook Pro (early 2011) i7 (2.0), with a bad case of liquid on the LVDS connector.

I already replaced that whole connector (handy to have a microscope and some nice hot air equipment available).

BUT, I'm still getting no backlight.

The panel powers when the board is fired up (ie. the data section shows a change of data). However, no backlight.

I've been a bit stumped on where to find the WLED driver for the i7 unit.

Any help?


BTW, this thread is one of the best I've seen on any forum. Ive been able to help NUMEROUS folks with 13" board damage as a result of this thread... thanks!

 

[wedgeman]

well,

In follow up to my own question - i found the answer!

Macbook Pro Early 2011 15" (with Thunderbolt).

The backlight fuse is on the backside (bottom) of the logic board, near the left cooling fan power plug. It's marked with a "P".

see attached photos.

From what i can tell, there is an FET which switches the power to the backlight LED's, adjacent to the main LVDS connector. It is fed by a large zero ohm resistor, which is in turn powered thru this fuse. I have acquired the schematic for it, but haven't had a chance to fully inspect and confirm this. However, the unit has now been working for a number of hours with with this fuse replaced....

This was a beer spill, with the LVDS connector entirely submerged and powered on... All other functionality was intact, so it appears that the fuse did its job!

 

[dervmonkey]

Hi everyone, great forum, I've been a long time browser and have now registered as I have a query that google is unable to help with.

I've been reading (and re-reading) this thread for a few days trying to find a resolution for my lightly water damaged Mid 2009 MBP 13.3, everything working now - just the LED backlight.

I've checked the diode 74 and am getting 12.5v, pin 4 on the WLED driver IC seems to be at 3v and the 0402 fuse is intact. No burnt contacts or missing components, board cleaned twice just to be sure.

Reading through the thread I beleive the LP8534 needs changing, I've had a quote to repair but don't have much confidence in the company offering the quote and feel the bill would increase when they actually got the machine in front of them.

I'm trying to decide wether to spend my money on a reasonable hot air station and magnifying gear, along with the WLED driver IC - I'm a pretty competent guy with regards fixing stuff - the only stumbling block is the availability of the LP8543 in the UK - Farnell (I think) show as having stock, but in the Newark (NJ?) warehouse and want £16 to transfer stock to the UK, the IC itself is listed as under £3

Does anyone know of a UK stockist of the WLED IC?

 

[l.a.rossmann]

I have about 15 different logic board models here. I was thinking of compiling a list of images using a micro lens and a Nikon D3000 camera, with labels of what board part # is in the photos to make processes like this simpler. I'm going to do my best to start tomorrow.

----------

I'm trying to decide wether to spend my money on a reasonable hot air station and magnifying gear, along with the WLED driver IC - I'm a pretty competent guy with regards fixing stuff - the only stumbling block is the availability of the LP8543 in the UK - Farnell (I think) show as having stock, but in the Newark (NJ?) warehouse and want £16 to transfer stock to the UK, the IC itself is listed as under £3

Unless the tools you buy are absolute garbage, the cost of the tools to perform this job well will be more than the cost of a qualified technician performing the job for you. Plus, when they do it, you can throw it in their face if it doesn't work and not pay them! A joy you don't get if you buy your own gear.

What quote did you get and what tools are you looking at to perform the rework? Some of those cheap hot air sets really suck. Link me so I can see what you're getting, I'd hate for you to wind up with some dud rework kit that dies in a week. There are some fairly good cheap ones, but I am not sure what stores you have in the UK, so if you point me to the online store you're looking at, I can see what they have for you.

 

[dervmonkey]

Louis , thanks for the frank reply.

I've been quoted £175 to do the work, it's not so much the price they have quoted but the lack of confidence I have with them as a company - I think they are quoting for a replcement LCD panel going by the wording they used, also they claim they will ensure Windows is updated with the latest drivers etc - I find that odd as it's clearly stated in my query that it's an MBP and it requires a WLED driver IC fitting, whilst claiming they "repair hundreds of these issues a week" hard to believe and not confidence inspiring at all, they are a local company to me, but insist I pay for courier collection/delivery even if I drop it off and collect myself.

I haven't decided which rework gear to get as yet, I'm still looking into it, but for the purposes of the occasional SMD rework I don't really need a full on industrial bit of kit - but I do get your point, if you know of a reasonable budget rework station could I have a link so I can find a stockist in the UK please?

Thanks

Andy

 

[insiderla]

Hi guys,

I've got a big problem with my MBP A1278 and I hope you can help me
My Macbook fell on the floor and since this the backlight does not work anymore... I changed the LCD cable and the display already, but it was not successful.. I read about the fuse on the backside of the logicboard (the fuse with the white point) and checked this with a multimeter and it whistled.

What can I do? Please help me..

Best wishes

Michael

Is nobody here to help me?
please help me. What can i do

Michael

 

[Dadioh]

Is nobody here to help me?
please help me. What can i do

Michael

Further back in the thread are the measurements for the WLED driver pins resistance to ground. You should measure each pin to ground and compare to the tables. That will help narrow down the problem.

 

[Loomingx]

I have a Macbook A1260 with no backlight. I have replaced the entire LCD assembly/inverter board to confirm that this is a mainboard issue. From what I've read in this thread this is most likely a blown fuse. I have tested some fuses that I have been able to see but I'm sure i've missed a few. Is there any way someone can show me which fuse generally needs to be replaced on a A1260 model? I've seen that the F9800 is generally the issue but I can't find it for the life of me!

Here's some pictures of the board:

 

[eecky]

Macbook pro 15 i5 Mid 2010

Hello,

I think the wled driver is bad of my macbook pro i5 (2,53) mid 2010.
I know it is a wled driver LP8543 but can i use another wled driver.

I have found here in belgium a store, but they don't have the LP8543.
So my question is if i can use this Wled driver to replace the LP8543.

Thanks
Christophe

 

[Dadioh]

Hello,

I think the wled driver is bad of my macbook pro i5 (2,53) mid 2010.
I know it is a wled driver LP8543 but can i use another wled driver.

I have found here in belgium a store, but they don't have the LP8543.
So my question is if i can use this Wled driver to replace the LP8543.

Thanks
Christophe

Are you sure it is a LP8543? The other 2010 models I am aware of have changed to the LP8545. I would just double check the number on the device.

Secondly, the pin outs on the device you linked are completely different that either the 8543 or 8545. You need to get the correct WLED direct replacement for your logic board.

http://www.digikey.ca/product-detail/en/LP8543SQ/NOPB/LP8543SQ/NOPBCT-ND/2353187

http://www.newark.com/national-semiconductor/lp8543sqe-nopb/ic-led-drvr-llp/dp/55R4252?Ntt=lp8543

Maybe you can convince them to ship to you.

----------

I have a Macbook A1260 with no backlight. I have replaced the entire LCD assembly/inverter board to confirm that this is a mainboard issue. From what I've read in this thread this is most likely a blown fuse. I have tested some fuses that I have been able to see but I'm sure i've missed a few. Is there any way someone can show me which fuse generally needs to be replaced on a A1260 model? I've seen that the F9800 is generally the issue but I can't find it for the life of me!

Here's some pictures of the board:

I have no experience with this board but knowing Apple the design is "probably " similar to the unibody designs. Look front and back near the LVDS connector and try to find a beige device with either a white dot or the letter "F" on it. I can not zoom in close enough on the photos to help you.

Good luck.

 

[aleds1234]

Blinks when connecting unibody macbook pro early 2011, no backlight

I have such problem with unibody macbook pro early 2011, has no backlight, connecting magsafe blinks fraction of a second display, external monitor to connect all normal, you need to change the fuse? worth mentioning that I have detected a P brings up, which means that flashes when connected? Greetings!

 

[Loomingx]

Here's the best I could do.

 

[Dadioh]

Here's the best I could do.

Good job. Unfortunately I don't have a schematic for the pre-unibody MacBooks and I am unable to determine if there is a similar circuit for the backlight. Maybe someone else with experience with these MacBooks can chime in.

 

[Loomingx]

Damn. You seem to be the god of Backlight fix's. If you're unsure I'm not sure how much luck I'm going to have elsewhere. Thanks for looking over the photo's though!

 

[Dadioh]

Damn. You seem to be the god of Backlight fix's. If you're unsure I'm not sure how much luck I'm going to have elsewhere. Thanks for looking over the photo's though!

Thanks for the compliment. I just choose to focus on the Macbook unibody designs because they are so much easier to dis-assemble and work on. Good luck with your search. I did notice there are some fuse designations on the larger green components. It is possible that on the older design they used a larger body fuse for the backlight so you might try checking those green devices to see if they are showing zero (or close to zero) ohms. Best thing I can think of for now.

 

[Loomingx]

Unfortunately I already checked them and I got good readings. I was hoping there was a smaller one that I had missed. (which is still entirely possible)

 

[Mikf]

Hi all!

Yesterday i bought a Macbook pro mid 2009 (2,66GHz, 15,4") with a non working backlight. The screen is showing picture.

I read some posts in this forum threat and i decided to get the logic board out. I measured some points, i hope you guys can point me in the right direction.

Here is my logicboard:


Here are the measured values:
1: Some resistance .000
2: Some resistance .000
3: 0.300
4: Nothing 1.

So I guess my fuse is blown, am I right? Are the other values good?

Thank you in advance. And sorry for the bad English, I'm from Holland.

-Edit- Is this the fuse to get?