MacBook Pro Unibody - No Backlight - Logic Board Question

[Dadioh]

I have just switched with a new Macbook screen and it works like a charme ! Thank you.

Great news. I think that is the first “stage light” (as I call them) that was not the logic board. I guess screen LED can go bad too on occasion.

 

[icemith]

I have 2009 MacBook pro backlight problem, I measure f9800 and get 12,6v but on pin 2 I got 1,2v I try to replace the fuse and get 12,6v on pin 1 and 2 but later just for a minute I got back 1,2v on pin 2 again. what is the problem ,can you help me?thk b4

 

[Dadioh]

I have 2009 MacBook pro backlight problem, I measure f9800 and get 12,6v but on pin 2 I got 1,2v I try to replace the fuse and get 12,6v on pin 1 and 2 but later just for a minute I got back 1,2v on pin 2 again. what is the problem ,can you help me?thk b4

The fuse is blowing because you gave a short circuit somewhere. Most likely at the 2 pins on the LVDS connector that carry the backlight voltage. With power OFF you need to measure resistance from those pins to ground.

 

[icemith]

The fuse is blowing because you gave a short circuit somewhere. Most likely at the 2 pins on the LVDS connector that carry the backlight voltage. With power OFF you need to measure resistance from those pins to ground.

thk for help i'll try to measure

 

[Raik]

Macbook Pro early 2008
logic: 820-2249-a
IO: 820-2273-A

I got this device for free from a friend years ago. I don't know anything about what causes the failure. As far as i remember (i've disassembled and checked it a year ago), except the backlight everything worked.

I've found a white, blown fuse F9800 at the bottom of the IO board. Haven't found the WLED driver yet.
Is this the backlight fuse?
EDIT: answer found:
https://forums.macrumors.com/threads/macbook-pro-backlight-fuse-locations.1629823/#post-24689178
Yes, it is. But where is the WLED driver?

 

[dtruong]

Thank all of you with many guides in detail!

Managed to solve no-backlight issue using a piece of copper wire and old soldering tool. I like my old Macbook (MC700 - mid 2011) very much and bringing it back makes me so happy. I will order some real fuses even thought have not known how to solder it yet.
Again, thank you all!

 

[macsoluter]

you can do this with a hot air device (see foto)

 

[cpufixer]

hi, I am stuck with a dead 820-3115-b, liquid damaged, was working for a bit, then started with black screen, acting up, then total dead...did a SMC reball now have green light and charging..but no cpuvcore..will give one usb stick flash...when power applied..I am lost right now...

 

[techinfant]

I'm humbled to be able to revive this epic thread, and look forward to your input on my backlight issue. Here is the backstory:

• I took apart my 2009 MacBook Pro 13 to show my 10yo daughter how a laptop works. Since we were in there, we reapplied thermal paste so it runs cooler. However, after putting it back together, we found the MagSafe wasn't lighting up. We opened it back up and realized that a logic board screw had cut through one of the wires of the DC-in board. I soldered the wire-back together, and we got our Magsafe light back, but when we hit the power button, the backlight blinked and went out. We hit power again, and it blinked one last time and went dark. However, we could hear the fan running, and the keyboard backlight came on. After some research, we determined that the backlight wasn't working, but we're getting video on the screen, and the laptop works more or less normally when connected to an external monitor.
• After stumbling upon this thread as well as some other resources on backlight issues, we were able to determine the following:
  • The backlight fuse is blown.
  • The impedance to ground for the WLED pins is generally consistent with what is posted in the first post in this thread, but not exactly the same. I don't know if this confirms a blown WLED or not.
  • When I connect just the logic board to power (even with a new DC-in jack) with RAM installed and the fan connected, the board shows no signs of life. Even shorting the power-on pads doesn't turn power on. However, when I reassemble the board fully, I can turn it on with the power button, minus the backlight.
• I have ordered a new DC-in jack and a backlight fuse, along with tools (solder and rework station) and a multimeter to replace the fuse. I have also ordered a cheap used logic board for parts, if needed.
• Questions:
  • How should I go about troubleshooting the board (820-2530) to identify the underlying problem that caused the fuse to blow, and how can I check whether that problem still exists? (I'm trying to avoid replacing the fuse and having it blow again).
  • Is there a way to check whether the WLED driver is functioning properly?
  • Is the fact that I'm not getting "fan-spin" when powering just the logic board a related problem?
  • What is the quickest way to check the health of this logic board with a multimeter?

Many thanks in advance for your help, and thank you to @Dadioh and everyone else for documenting your findings here!

 

[techinfant]

Happy to join the legion of folks who posted on this thread with Macbooks that were resurrected by replacing the backlight fuse. ?

 

[Roxanne63]

Hello To all
I have a macbook 13" 2011 I7 820-2936B
Backlicht problem.
but fully functional.
first diagnostic display external screen good.
display on integrated screen good view via lamp behind the apple
but without backlight passage to the multimeter of the F9700 fuse continuity test
Fuse out of order Removal of the fuse measuring points
point 1: 6.649 Kohm
point 2: 2.786 Mohm
point measurement macbook lit without fuse
dot 1: 12.52V
point 2: 2.10V to 2.20V
Installation of the new fuse the Macbook turns on and it cuts after 3 to 5 seconds after launching dvd player
removal of the new fuse still good
Macbook boots without shutting down
good LVDS cable try on 2 different cable and screen
Do you have an idea?
advice?
is the U9701 and the problem?
sorry for my english

 

[Roxanne63]

hello
no one to help me ?

 

[GigabitEthernet]

Hi,

I have a 2012 unibody with a 820-3330-B, showing no backlight or display. LCD_PWR_EN showing 0V out of U9600, can anyone help?