MacBook Pro Unibody - No Backlight - Logic Board Question

[Dadioh]

Hi Mori3000,

thanks for your fast reply.
Must be a problem with ImageShack.
I've attached it diretly to this post, should be in full res now.

Thanks for you help.

That looks like the fuse. Did you measure it to see if it was open (high impedance)? If so then you would replace this. Also probably worth a quick check of the impedance top ground on the backlight voltage to make sure there is not another fault still present.

Measure at the 3 pins indicated below.

 

[Dadioh]

Can you post a picture of the damaged traces on the logic board. There is always hope

----------



Dadioh, sorry for the delay. Been preoccupied. Here is a pic of the connector with some missing traces. Any suggestions would be greatly appreciated. Thank you again for your assistance.

Yikes. That would be a pretty messy fix. You basically would need to install the connector and scrape off the solder resist on the traces, and install very fines wires from the connector pins to the traces.

OR...

If everything works except the backlight then convert this machine into a media center.

1) Remove the display.
2) Get a Wireless N USB adapter and a Bluetooth USB adapter.
3) Run display to a TV with a miniDP to HDMI cable
4) Connect sound via TOSlink to Surround receiver or by stereo jack to external speakers.
5) You can control the setup from your couch using a bluetooth keyboard or install Rowmote on your iPhone/iPod/iPad and use those as a remote.
6) Run Plex for media streaming, Netflix, Hulu, whatever....

I have done this on 3 different media setups and it works great. The Macbook is an attractive media center with the added benefit of built in keyboard and trackpad.

 

[Mori3000]

Hi Dadioh

yesterday i fixed a macbook pro that had no back light, by shorting the fuse,and i teated it about two hour with a spare LCD and LVDS cable.

But just when i connected back the orginal cable and lcd the logic board smoked up.

To repair it i replaced the

lcd connector
shorted the fuse
replaced the driver 8543 ( taken of a mac which got water too and not starting )
replaced the diode
replaced the transistor R33F
Replaced the white capacitator for the lcd

What can i do more?

 

[user000815]

That looks like the fuse. Did you measure it to see if it was open (high impedance)? If so then you would replace this. Also probably worth a quick check of the impedance top ground on the backlight voltage to make sure there is not another fault still present.

Measure at the 3 pins indicated below.

Hi Dadioh, hi Mori3000
thanks again for your help.
I've checked the fuse and the pins on the connector.
It seems to be the fuse. No Voltage on the pins and a high resitance at the fuse.
I've ordered new once and will try to fix it.
I will tell you if I had sucess.

Many thanks for your help.

 

[Mori3000]

Hi Dadioh, hi Mori3000
thanks again for your help.
I've checked the fuse and the pins on the connector.
It seems to be the fuse. No Voltage on the pins and a high resitance at the fuse.
I've ordered new once and will try to fix it.
I will tell you if I had sucess.

Many thanks for your help.

Can i ask you where you ordered the fuse from? I could not find it any where that i know.

By the way you do not need to thank me because i got these information of Dadioh som days ago, and before that i had no idea how and where the fuse is.

 

[Mori3000]

Hi Dadioh again

I have two questions and i hope you can help me

The first is a macbook pro 13 2010 which was not starting, efter the cleaning of the logic card the MBP started but no backlight, i shorted the fuse and tried the MBP by a spare LCD & LVDS cable and it worked without any problem.

Then when i tried to put back the original LCD & LVDS cable, I got a little smoke around the LCD connector, yes the lcd connector broke down and then here is what i did:
I replaced the lcd connector, STILL NO BACKLIGHT
I shorted the fuse, STILL NO BACKLIGHT
replaced the driver 8543 (it is taken of a mac which spilled water on it and not starting and i,m not sure if the driver workes ), STILL NO BACKLIGHT
I replaced the diode, STILL NO BACKLIGHT
I replaced the transistor R33F STILL NO BACKLIGHT
I replaced the white capacitator for the lcd, STILL NO BACKLIGHT

The second is a Macbook air 13" 2011,
It is spilled water on it too, and it is like this when i got it, when i connect the megasafe the fan runs maybe one or two secondes and then it stopes working and nothing more, and when i start it from the keyboard so it is the same thing.

I cleaned the logic card but it is still exakt the same problem the fan just runs in 1 or 2 secondes and nothing more.

I apriciate your assistans and time fro reading this.

 

[Mori3000]

I was looking at the logic card for macbook air and i found a device which seems have problem, But i do not know what it is and where to find it

 

[user000815]

Can i ask you where you ordered the fuse from? I could not find it any where that i know.

By the way you do not need to thank me because i got these information of Dadioh som days ago, and before that i had no idea how and where the fuse is.

Hi,

I've ordered at rs-online.com that was the cheapest offer.
Have a look at
http://de.rs-online.com/web/p/nicht...2267573743D3730372D363738392677633D4E4F4E4526
But be aware that they do not sell to end user or private customer.
If you need one or two, I've ordered 10 (that was the minimum), send me a PM.

Regards,

----------

I was looking at the logic card for macbook air and i found a device which seems have problem, But i do not know what it is and where to find it

Hi Mori,

I'm not 100% sure, but it could be the power supply for the RAM.
have a look at the following link.
http://www.ti.com/product/tps51916
Maybe somebody with more information about it could verify this.

Regards,

 

[Dadioh]

Check earlier in the thread for links for where to purchase the fuse. I get them from digikey or Newark. Just search for 0402 size 2A.

 

[Dadioh]

Hi Mori,

I'm not 100% sure, but it could be the power supply for the RAM.
have a look at the following link.
http://www.ti.com/product/tps51916
Maybe somebody with more information about it could verify this.

Regards,

That is correct. This is the 1.5V supply for the memory. Won't get far if this is broken

 

[user000815]

That is correct. This is the 1.5V supply for the memory. Won't get far if this is broken

Ok, I've read a bit in the data sheet from TI.
The marked Pins are Pin 12 and Pin 15.
Both are used as Input.
Have a look at the data sheet there are test measurements to check if they are working corectly.

Here is the data sheet
http://www.ti.com/lit/ds/symlink/tps51916.pdf

Good luck

 

[Dadioh]

Hi Dadioh again

I have two questions and i hope you can help me

The first is a macbook pro 13 2010 which was not starting, efter the cleaning of the logic card the MBP started but no backlight, i shorted the fuse and tried the MBP by a spare LCD & LVDS cable and it worked without any problem.

Then when i tried to put back the original LCD & LVDS cable, I got a little smoke around the LCD connector, yes the lcd connector broke down and then here is what i did:
I replaced the lcd connector, STILL NO BACKLIGHT
I shorted the fuse, STILL NO BACKLIGHT
replaced the driver 8543 (it is taken of a mac which spilled water on it and not starting and i,m not sure if the driver workes ), STILL NO BACKLIGHT
I replaced the diode, STILL NO BACKLIGHT
I replaced the transistor R33F STILL NO BACKLIGHT
I replaced the white capacitator for the lcd, STILL NO BACKLIGHT

The second is a Macbook air 13" 2011,
It is spilled water on it too, and it is like this when i got it, when i connect the megasafe the fan runs maybe one or two secondes and then it stopes working and nothing more, and when i start it from the keyboard so it is the same thing.

I cleaned the logic card but it is still exakt the same problem the fan just runs in 1 or 2 secondes and nothing more.

I apriciate your assistans and time fro reading this.

Check the impedance to ground for all the pins on the 8543. If there is something wrong in the circuit it should show up. Earlier in this thread I posted the values that you should be seeing.

 

[Mori3000]

Hi Dadioh and user000815.

Thank you for the your assistans for the macbook air, i removed that power supply for the RAM (tps51916), and there were two of the pointes disconnected on the logic card, Ifixed som wire for them and put back the IC, and it is working again.

Thanks too much

 

[enigmo08]

Macbook 2008 Unibody non-Pro

Hi everyone, I read through this thread and I wanted to make sure I had the right information. This question can be answered by anyone, but I assume Dadioh knows the most on the subject, for the backlight issue on this model is it this part here: https://forums.macrumors.com/attachment.php?attachmentid=287076&d=1306515908 that needs to be replaced? Or does it also have a driver like the newer macbook pros. I took apart the computer and using a multimeter it read 0, so either my pins on the multimeter weren't small enough or it actually is reading zero meaning it needs to be replaced. Am I headed the right direction with this?

 

[Dadioh]

Hi everyone, I read through this thread and I wanted to make sure I had the right information. This question can be answered by anyone, but I assume Dadioh knows the most on the subject, for the backlight issue on this model is it this part here: https://forums.macrumors.com/attachment.php?attachmentid=287076&d=1306515908 that needs to be replaced? Or does it also have a driver like the newer macbook pros. I took apart the computer and using a multimeter it read 0, so either my pins on the multimeter weren't small enough or it actually is reading zero meaning it needs to be replaced. Am I headed the right direction with this?

First of all if you have the Macbook Unibody Aluminum non-Pro 2008 then that is the correct fuse that controls the backlight circuit.

Second, when you say you are measuring 0 is this measuring the resistance of the fuse? When the fuse is good it will measure 0 (or close to 0) ohms resistance. When it has blown it will measure megohms of resistance. So your fuse may be OK if this is 0 ohms you are measuring. You may require a deeper dive into diagnostics if that is the case.

 

[Mori3000]

Hi again

This time i have another macbook pro 13 2010, as the previous ones, it is spilled water on it too.

When i start it the computer powers on and starts the process after about 1 minute it turns off totally, i feel the board but it is not very warm, but if i start it directly it just after mayby 5 secondes turns off again, seems like there is no fan or getting to hot. but i did not feel it very hot to turn off.

what could it be?

By the way i cleaned the board.

 

[enigmo08]

First of all if you have the Macbook Unibody Aluminum non-Pro 2008 then that is the correct fuse that controls the backlight circuit.

Second, when you say you are measuring 0 is this measuring the resistance of the fuse? When the fuse is good it will measure 0 (or close to 0) ohms resistance. When it has blown it will measure megohms of resistance. So your fuse may be OK if this is 0 ohms you are measuring. You may require a deeper dive into diagnostics if that is the case.

I set my multimeter to all the Ohm settings I could (i.e. x10, x100, x1K) and the needle didn't move. I made sure the multimeter was working before I checked the fuse. If it is good, I should just have to replace the screen?

 

[Dadioh]

I set my multimeter to all the Ohm settings I could (i.e. x10, x100, x1K) and the needle didn't move. I made sure the multimeter was working before I checked the fuse. If it is good, I should just have to replace the screen?

From my experience it has never been a bad screen. If the fuse is good then it is most likely either an issue with the WLED driver circuit or the lvds connector/cable. Next step is to measure resistance (impedance) to ground on all the pins of the WLED driver. Then refer to the chart earlier in the thread. You probably will need fine probe set for your multimeter to probe the fine pins on the driver.

 

[enigmo08]

From my experience it has never been a bad screen. If the fuse is good then it is most likely either an issue with the WLED driver circuit or the lvds connector/cable. Next step is to measure resistance (impedance) to ground on all the pins of the WLED driver. Then refer to the chart earlier in the thread. You probably will need fine probe set for your multimeter to probe the fine pins on the driver.

Alright I'll give that a try this weekend. What setting should I have the multipmeter at when I'm doing this?

 

[enigmo08]

Hi Dadioh, I realized I made a foolish mistake, I was reading my Ohmeter wrong it was actually staying at 1, and I hadn't checked by touching the pins together. So I assume its the fuse that needs to be replaced, because when I tested the fuse it read 1 and the needle did not move. So maybe its not the WLED driver? In your cases has it ever been both the WLED driver as well as the fuse? And how fast is the shipping from digikey? I'm hoping I can get it in a few days, will I still need someone to solder it or is it something I shold be able to do? Thanks for the help and I'll let you know how it goes!

 

[Dadioh]

Hi Dadioh, I realized I made a foolish mistake, I was reading my Ohmeter wrong it was actually staying at 1, and I hadn't checked by touching the pins together. So I assume its the fuse that needs to be replaced, because when I tested the fuse it read 1 and the needle did not move. So maybe its not the WLED driver? In your cases has it ever been both the WLED driver as well as the fuse? And how fast is the shipping from digikey? I'm hoping I can get it in a few days, will I still need someone to solder it or is it something I shold be able to do? Thanks for the help and I'll let you know how it goes!

The fuse blew because something shorted in the WLED circuit. That short may have been temporary (like a water spill that has dried) or it could be semi-permanent (residue left behind which is still conducting and requires cleaning to remove the short), or it could be permanent (WLED driver has internal short and needs to be replaced).

First step, if this was a liquid spill, is to clean the affected area with pure isopropyl alcohol and a brush. Then replace fuse. This usually requires fine tip soldering iron and magnification. Then check the resistance of the backlight voltage output to ground to make sure it is not shorted. If the short still exists then the fuse will blow. If not, and the short was a temporary condition then you should have a working backlight.

Good luck.

 

[user000815]

Hi Dadioh, hi Mori3000
thanks again for your help.
I've checked the fuse and the pins on the connector.
It seems to be the fuse. No Voltage on the pins and a high resitance at the fuse.
I've ordered new once and will try to fix it.
I will tell you if I had sucess.

Many thanks for your help.

Hi all,

I've got the fuse and wow they are damm small.
After three frustrating hour with trying on an old board I was able to get the old fuse out and the new one in.
But with no success
I've measured again the 638Z and there are 300k Ohm. Unfortunately there are 0 Volt at the LVDS connector.
I've checked the LVDS cable and the last two pins are broken and bended together.
Could it be something else than the WLED driver?

Many thanks in advance for your help.

Regards,

 

[Dadioh]

Hi all,

I've got the fuse and wow they are damm small.
After three frustrating hour with trying on an old board I was able to get the old fuse out and the new one in.
But with no success
I've measured again the 638Z and there are 300k Ohm. Unfortunately there are 0 Volt at the LVDS connector.
I've checked the LVDS cable and the last two pins are broken and bended together.
Could it be something else than the WLED driver?

Many thanks in advance for your help.

Regards,

Did you check the new fuse once you had it in place? Fuses are thermally activated devices so they are sensitive to applying solder heat too long. If you had a lot of difficulty in the soldering process it is possible it blew during installation.

 

[user000815]

Did you check the new fuse once you had it in place? Fuses are thermally activated devices so they are sensitive to applying solder heat too long. If you had a lot of difficulty in the soldering process it is possible it blew during installation.

Hi Dadioh,

thnaks for the fast reply. Yes the fuse is working.
I needed most of the time for exercises and get out the old one.
Soldering in the new wasn't a problem.

Regards,

 

[finemac]

13" MacBook A1342 LCD Backlight issue

Hi Dadioh,

I have read through this thread and it's really amazing! However, from what I can tell the problem I have is that a fuse has blown on the logic-board close to the LVDS cable due to me replacing the LCD screen as it was cracked.

The replacement went okay but the new LCD was faulty with a loose internal connection which I found by moving the inverter attached to the bottom of the LCD. While doing this the backlight just stopped working and now I have installed a working LCD but I have no backlight.

So, from reading this thread it would appear that a fuse has blown but I'm lost as to where a which one it might be, please help!

I have attached a pic of the Logic-board close to the LVDS connection for you to have a look at and possibly tell me where the fuse might be and also a pic of the laptop specs.

Thanks so much for your help!

Best Wishes.

F