MacBook Pro Unibody - No Backlight - Logic Board Question

[symuncez]

Hello Guys, thank you for this magnificent thread. It helps a lot.


I`m dealing with MBP 15" - i7. Logic board 820-2915-A.

After trying LED replacement it came with NO Backlight & No Image on the screen. But it works on External Screen.


I`m attaching the Schematic if you want to digg in.

I`m out of ideas guys, please advice.

G.

G,

I'm out of my league here, as my experience has only been with (very) simple electronics, like for cars. Certainly a learning experience for me.

I hope I'm not out of bounds for asking this but, where are you guys getting schematics from? And how do you know how certain components work for what purposes?


Meanwhile, it'll be interesting to see what the resolution to your issue is.


-symuncez

 

[zixu]

G,

I'm out of my league here, as my experience has only been with (very) simple electronics, like for cars. Certainly a learning experience for me.

I hope I'm not out of bounds for asking this but, where are you guys getting schematics from? And how do you know how certain components work for what purposes?


Meanwhile, it'll be interesting to see what the resolution to your issue is.


-symuncez

Thanks for your reply symuncez :beer:

Schematics are (in most cases) hard to hunt. You need to dig deeply. Especially with these annoying 1000pgs offering to buy that sch. Thank god Google is helping with Chinese/Russian/Polish/... translation.

For component tracking and diagnostic you need at least basic electronic knowledge (caps, resistors, mosfets, power ics, etc.) It gets harder and time consuming when you work with smd and non-labeled cmpnts on the boards. Then you need to search them on board view, if you have it of course (its harder to find than schematic). :banghead:

But after many, many years in troubleshooting you are starting to feel the things. And its more easy when customer is honest when you ask him "What happened before it died?" question.

But in cases like this something simple can lead you to deep .... issues.

Hopefully someone will come out with tough about this one.


Thanks guys, great community is concentrated here.

 

[Musicsoul78]

Thanks for your reply symuncez :beer:

Schematics are (in most cases) hard to hunt. You need to dig deeply. Especially with these annoying 1000pgs offering to buy that sch. Thank god Google is helping with Chinese/Russian/Polish/... translation.

For component tracking and diagnostic you need at least basic electronic knowledge (caps, resistors, mosfets, power ics, etc.) It gets harder and time consuming when you work with smd and non-labeled cmpnts on the boards. Then you need to search them on board view, if you have it of course (its harder to find than schematic). :banghead:

But after many, many years in troubleshooting you are starting to feel the things. And its more easy when customer is honest when you ask him "What happened before it died?" question.

But in cases like this something simple can lead you to deep .... issues.

Hopefully someone will come out with tough about this one.


Thanks guys, great community is concentrated here.

well put sir...

from my experience when its not the fuse or wled driver
trace back to the source and work your way up the stream.
the voltage might drop which causes wled not to be enabled. ( this was due to a slight cut trace)
could not believe it when i found it

 

[SirgMFK]

Can someone help identify those components on MacBook Pro 13" Early 2011 logic board? Marked on yellow and red. http://i.imgur.com/lVcSvdJ.jpg

 

[zixu]

If it is Apple Macbook A1278 - K90i - 820-2936

Can someone help identify those components on MacBook Pro 13" Early 2011 logic board? Marked on yellow and red. http://i.imgur.com/lVcSvdJ.jpg

If it is Apple Macbook A1278 - K90i - 820-2936

Then your squared components should be:

U9701 - LP8550 - Wled Driver - https://docs.google.com/viewer?a=v&q=cache:r2sOti7Opf8J:www.ti.com/general/docs/lit/getliterature.tsp%3FliteratureNumber%3Dsnvs657a+&hl=en&gl=uk&pid=bl&srcid=ADGEESj5NLHbAThXRL9dvn1s0rm5PWfr_fUAK9lr6TYZc1DQ6f-CujZoxuxoTCRqon-beImxjbgClD_9zmHa0ns-2JeXYooIpnmtpM8g0ukKcXffwh5gBnIqnQm8QsVxV4p1JwQXREog&sig=AHIEtbRbdnp3meFsy6_ISU_ToNRgf0D7iw

U5400 - INA213 / SC70 - High Side Current Sense / Filter - https://docs.google.com/viewer?a=v&q=cache:VKMgdkh4ZqEJ:www.ti.com/lit/ds/symlink/ina213.pdf+&hl=en&gl=uk&pid=bl&srcid=ADGEESjevpOXrDdBmhmquRPJ0FIMR7Z0c06H2zCztXgixfzI1qCGoKXq4DzaZbiX9LtZKvE7eEhN2V2Ai15kb6YK5mITlv13RSEicwRDjoTqWuvkHQR7ev0xw08lOV-X7tiI19UIilNX&sig=AHIEtbTLcnahrFWlZYllY8S3NUFokjL2-Q

U3890 - LT3957 - Voltage converter - https://docs.google.com/viewer?a=v&q=cache:nBPEzZJdfPoJ:www.linear.com/docs/29446+&hl=en&gl=uk&pid=bl&srcid=ADGEEShDBfz7S-0CEziIQmHxV0RPTu0S4QfFLniV8jxEoGNlCaRfD25OkUUBaux-Bsz8ao8zWtD8RUSsE2ZnpQKVEriTvMQE-Mi8CroXoyfhOfwa_aOj63SbNX8k7qi7pLyWUbsQnaKx&sig=AHIEtbRDCqQMqXTeOuM-EpXDWkRXmQWBXg

 

[l.a.rossmann]

Thanks for your reply symuncez :beer:

Schematics are (in most cases) hard to hunt. You need to dig deeply. Especially with these annoying 1000pgs offering to buy that sch. Thank god Google is helping with Chinese/Russian/Polish/... translation.

For component tracking and diagnostic you need at least basic electronic knowledge (caps, resistors, mosfets, power ics, etc.) It gets harder and time consuming when you work with smd and non-labeled cmpnts on the boards. Then you need to search them on board view, if you have it of course (its harder to find than schematic). :banghead:

But after many, many years in troubleshooting you are starting to feel the things. And its more easy when customer is honest when you ask him "What happened before it died?" question.

But in cases like this something simple can lead you to deep .... issues.

Hopefully someone will come out with tough about this one.


Thanks guys, great community is concentrated here.

The single hardest thing to figure out as a beginner is which component on the schematic is which on the board.

 

[SirgMFK]

If it is Apple Macbook A1278 - K90i - 820-2936

Then your squared components should be:

Image

U9701 - LP8550 - Wled Driver - https://docs.google.com/viewer?a=v&q=cache:r2sOti7Opf8J:www.ti.com/general/docs/lit/getliterature.tsp%3FliteratureNumber%3Dsnvs657a+&hl=en&gl=uk&pid=bl&srcid=ADGEESj5NLHbAThXRL9dvn1s0rm5PWfr_fUAK9lr6TYZc1DQ6f-CujZoxuxoTCRqon-beImxjbgClD_9zmHa0ns-2JeXYooIpnmtpM8g0ukKcXffwh5gBnIqnQm8QsVxV4p1JwQXREog&sig=AHIEtbRbdnp3meFsy6_ISU_ToNRgf0D7iw

U5400 - INA213 / SC70 - High Side Current Sense / Filter - https://docs.google.com/viewer?a=v&q=cache:VKMgdkh4ZqEJ:www.ti.com/lit/ds/symlink/ina213.pdf+&hl=en&gl=uk&pid=bl&srcid=ADGEESjevpOXrDdBmhmquRPJ0FIMR7Z0c06H2zCztXgixfzI1qCGoKXq4DzaZbiX9LtZKvE7eEhN2V2Ai15kb6YK5mITlv13RSEicwRDjoTqWuvkHQR7ev0xw08lOV-X7tiI19UIilNX&sig=AHIEtbTLcnahrFWlZYllY8S3NUFokjL2-Q

U3890 - LT3957 - Voltage converter - https://docs.google.com/viewer?a=v&q=cache:nBPEzZJdfPoJ:www.linear.com/docs/29446+&hl=en&gl=uk&pid=bl&srcid=ADGEEShDBfz7S-0CEziIQmHxV0RPTu0S4QfFLniV8jxEoGNlCaRfD25OkUUBaux-Bsz8ao8zWtD8RUSsE2ZnpQKVEriTvMQE-Mi8CroXoyfhOfwa_aOj63SbNX8k7qi7pLyWUbsQnaKx&sig=AHIEtbRDCqQMqXTeOuM-EpXDWkRXmQWBXg

Thank you zixu. Very helpfull.
One more thing I missed. What is the green component marked R005?

 

[zixu]

Thank you zixu. Very helpfull.
One more thing I missed. What is the green component marked R005?

It's Resistor SirgMFK



Meanwhile I found that I have also 3,3V at the BKLT_PLT_RST_L but 0V at LCD_BKLT_EN

LCD_BKLT_EN is coming from GMUX Chip /U9600/, which I still don't know what it's doing. According to Block Diagram /page 2 -8AB/ it looks like Chipset /U1800/ is enabling GMUX to give picture from Graphic Controller U8000 to LCD Panel.

And also when I forced Matrix turn on signal, /short 4,6pins on Q9706/ its turning ON the matrix but I don't have picture even without backlight.

It smells like even video signal is not reaching the LCD Panel.

I`m waiting authorization from customer to heat the GMUX chip its BGA, hopefully it will be cold joint something.

Common guys, throw ideas. I`m open to any suggestions.

G.

 

[Elddon]

Can someone help identify those components on led lighting MacBook Pro 13" Early 2011 logic board? Marked on yellow and red.

I do not have enough information about the board but I will gather it and tell you most details

 

[mountaindude]

Using old Macbook Air displays as light boxes?

First: What exceptionally good thread. I've spent an hour reading parts of it, still a bunch of pages to go.

So: I have a few cracked displays from Air laptops (unknown models). Looking forward to do a teardown, but I also thought I could use the screens as either light boards, or as lamps for use when taking photos of small objects.

In either of these cases I'd probably rip out the actual LCD (or whatever technology is used) panel and just keep the backlighting and diffuser layers. Maybe adding a sheet of plexi to replace a cracked screen.

My thinking is then to just force the backlighting high at max intensity. Maybe I even won't need a driver chip for this...?

Sounds doable/reasonable?

All the above would of course be a lot easier with schematics.. any good source for such, for the display subsystem of the various Macbook Air models? Have looked around but no real luck..
Specifically, the pinout of the LVDS connector attaching to the logic board would be useful. Anyone?

Thanks!

 

[bgt50]

I have a MB pro 17" type A1212 which has a black screen. Could anybody help me with this problem. I've found a defective part but the number is unreadable. Please help. With an external display it works fine.

 

[zixu]

I have a MB pro 17" type A1212 which has a black screen. Could anybody help me with this problem. I've found a defective part but the number is unreadable. Please help. With an external display it works fine.
Image

Dude this mosfet is for 3.3v screen/matrix power voltage supply.
It's Q9400 - SI3443DV, should be popular and easy to find. :thumbup:

This model looks like have separate inverter part.
For backlight issues should be checked Q9450 and U9453.

 

[bgt50]

Dude this mosfet is for 3.3v screen/matrix power voltage supply.
It's Q9400 - SI3443DV, should be popular and easy to find. :thumbup:
This model looks like have separate inverter part.
For backlight issues should be checked Q9450 and U9453.

Thx Zixu. Where can I find the other 2 parts you mentioned(for backlight issues)?

 

[blackburn]

I've got a macbook pro 13 inch 2009 model that doesn't charge (faint green light), I know it is the dc-in board, I've used another one from a white unibody macbook to test it and it works fine.

Now so far so good, but I having trouble sourcing another dc-in board, and from what I've seen it has a few resistors, a few caps, a inductor and some kind of transistor. Has anybody repaired one of those boards?

On side note, the battery does indeed charge but at the rate of 150mha so it is slow, and for some odd reason the mac started charging after being plugged in for a few hours and the light got stuck on solid orange even after it finished charging. And there is conductivity from the center pin to the logic board using the bad dc-in board.

 

[zixu]

Thx Zixu. Where can I find the other 2 parts you mentioned(for backlight issues)?

Ill check when i reach the office.
Do you have any dimm picture on your screen even without backlight?

This line should be for turning the screen on, so you cannot continue without replacing this mosfet.

 

[1278id10t]

a1278 emc 2419 backlight fuse location

Dadioh- can you help me find the location of my backlight fuse for this motherboard? You seem to be the 'man' who knows..Please any help would be great. I can see the laptop working in the display using a flashlight- so I have video..just can't find my way..thanks in advance.

 

[Dadioh]

Dadioh- can you help me find the location of my backlight fuse for this motherboard? You seem to be the 'man' who knows..Please any help would be great. I can see the laptop working in the display using a flashlight- so I have video..just can't find my way..thanks in advance.

That is the early 2011 model? The fuse is identified a few posts up from this one. See post by SirgMFK. It is the component with the "P".

 

[1278id10t]

wled fuse

It's Resistor SirgMFK



Meanwhile I found that I have also 3,3V at the BKLT_PLT_RST_L but 0V at LCD_BKLT_EN

LCD_BKLT_EN is coming from GMUX Chip /U9600/, which I still don't know what it's doing. According to Block Diagram /page 2 -8AB/ it looks like Chipset /U1800/ is enabling GMUX to give picture from Graphic Controller U8000 to LCD Panel.

And also when I forced Matrix turn on signal, /short 4,6pins on Q9706/ its turning ON the matrix but I don't have picture even without backlight.

It smells like even video signal is not reaching the LCD Panel.

I`m waiting authorization from customer to heat the GMUX chip its BGA, hopefully it will be cold joint something.

Common guys, throw ideas. I`m open to any suggestions.

G.

Zixu- Im an idiot but is the fuse with the 'p' on it next to the wled driver area the fuse for the backlight? my configuration looks the same but my board doesn't have a mark of 'p' on this fuse it's a dot...2011 mbp emc 2419. Thanks

----------

That is the early 2011 model? The fuse is identified a few posts up from this one. See post by SirgMFK. It is the component with the "P".

awesome! but mine has a dot instead of a 'p' is that normal? when I check ohm it comes up as a short..

 

[1278id10t]

yeah

Zixu- Im an idiot but is the fuse with the 'p' on it next to the wled driver area the fuse for the backlight? my configuration looks the same but my board doesn't have a mark of 'p' on this fuse it's a dot...2011 mbp emc 2419. Thanks

----------



awesome! but mine has a dot instead of a 'p' is that normal? when I check ohm it comes up as a short..

so after closer inspection it's got a 'p' so where can I get one of these fuses?

 

[zixu]

so after closer inspection it's got a 'p' so where can I get one of these fuses?

Glad you find the fuse. If you tell me board pn ex:920-xxxxx-xx or A1xxx mpb model number i will tell u the fuse model and spec.

But It should be 2amp or 3amp standard smd fuse depending on the model.

Based on where u live u can find them on ebay, radioshack or digikey like Dadioh mentioned.

But before replacement of the fuse, be sure that you DONT have continuity from fuse to ground. You can check both side of the fuse to ground with multimeter. To be sure there is still no short caused from previous fuse burn.

 

[bgt50]

Ill check when i reach the office. Do you have any dimm picture on your screen even without backlight?This line should be for turning the screen on, so you cannot continue without replacing this mosfet.

Ordered the mosfet and will replace it tomorrow. Hope it works then or could there be someting else causing the mosfet to blow?

 

[Dadioh]

I've got a macbook pro 13 inch 2009 model that doesn't charge (faint green light), I know it is the dc-in board, I've used another one from a white unibody macbook to test it and it works fine.

Now so far so good, but I having trouble sourcing another dc-in board, and from what I've seen it has a few resistors, a few caps, a inductor and some kind of transistor. Has anybody repaired one of those boards?

On side note, the battery does indeed charge but at the rate of 150mha so it is slow, and for some odd reason the mac started charging after being plugged in for a few hours and the light got stuck on solid orange even after it finished charging. And there is conductivity from the center pin to the logic board using the bad dc-in board.

You can find the DC-in board on eBay. I just ordered a few for $9. Make sure you get part number 820-2565-A. The magsafe from the 2008 Mabook aluminum is close but the screw holes don't line up.

I have repaired a few that were encrusted with liquid damage residue and corrosion by cleaning them and then using my hot air tool to reflow the solder. Need to be careful not to melt the wires. But for $9 for a new one I don't usually bother anymore.

 

[Dadioh]

so after closer inspection it's got a 'p' so where can I get one of these fuses?

3A
32V
0603 package

http://www.digikey.com/scripts/dkse...quantity=0&PV66=6&PV1293=55&PV343=216&stock=1

 

[bgt50]

Ordered the mosfet and will replace it tomorrow. Hope it works then or could there be someting else causing the mosfet to blow?

desoldering the blown mosfet got me a nasty pcb burnspot with 1 connection missing. Do you know where the legs of the chip are connected to?

 

[zixu]

desoldering the blown mosfet got me a nasty pcb burnspot with 1 connection missing. Do you know where the legs of the chip are connected to?
Image

Can you please check if the pins 1. 5 and 6 are connected to big black coil L9400 next to pin 6. Measure the continuity with the meter. pIN1 is marked with V.

If they are connected, then pins 1'2'5'6 are connected tgether.

Just bridge 1and2


Regards


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