A1278 MBP 820-3115-B No backlight (help needed)

Collapse
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • Gimi
    Senior Member
    • Aug 2015
    • 75
    • UK
    #1

    A1278 MBP 820-3115-B No backlight (help needed)

    Hi everyone. Got a MacBook pro a1278 2012 820-3115b motherboard. When powers on black screen and can see if light is flashed on apple logo. Keyboard and trackpad does not work but usb keyboard and trackpad works fine. Anyway when I log on it goes to sleep very quick. The sleep led indicator on all the time.
    Led output is stuck on 12.6v
    Changed 4 ic drives still the same.
    Then put a Windows hdd and backlight is on and keyboard works fine.
    NOW then : smc fault? Bios fault ? What the hell is wrong with this. Never had this before.
    Any help will be much appreciated.
    Thanks to all
    Tags: None
    • Gimi
      Senior Member
      • Aug 2015
      • 75
      • UK
      #2
      Re: A1278 MBP 820-3115-B No backlight (help needed)

      Anyone?

        Comment

        • Gimi
          Senior Member
          • Aug 2015
          • 75
          • UK
          #3
          Re: A1278 MBP 820-3115-B No backlight (help needed)

          All sorted. It was smc. Cool

            Comment

            • SunnyC
              New Member
              • Dec 2019
              • 3
              • Australia
              #4
              Re: A1278 MBP 820-3115-B No backlight (help needed)

              Hey!
              I've got a similar issue here, but it stays on a black screen with only the backlight on after the startup chime. Nothing else.
              I'm new to MacBook repair, but I've watched heaps of Louis Rossman videos.
              How did you figure out that it was the SMC?

                Comment

                Previous template Next

                Related Topics

                Collapse
                • triplefour
                  UN65TU700DF picture and sound but no backlight. BL tests ok but repl. PSU didnt fix!
                  by triplefour
                  this tv is throwing me for a loop. do samsung tvs no longer have the backlight self test feature built into the power supply?
                  i tested the backlight with my LED tester and it lights up both strips. one of them reads 100v and the other reads 63.7v.
                  unplugged mainboard from power supply but left backlight plugged in, and then plugged psu wall power in. expected to see backlights light up but see nothing.
                  according to how ive diagnosed in the past, this would almost always be a bad power supply. replacement power supply was cheap like 20$ from ebay. but still i get not even...
                  09-13-2023, 10:43 PM
                • luckydip
                  820-00840 no backlight after sleep
                  by luckydip
                  Came in dead, the backlight area and both rows of backlight caps were misaligned and fluxed.Got it working but has a sleep/backlight issue. When you close the lid, display darkens but when you open the lid the backlight doesn't restart - dim display as if no backlight. No other obvious liquid damage.

                  If you put it to sleep via the Apple menu then it wakes up fine with backlight.

                  Things I've tried - replaced hall sensor, replaced U5255 and given the SMC a light reflow - still no change. U5255 area resitors all ok. Any other ideas?

                  thanks...
                  09-03-2021, 05:53 AM
                • kingskie
                  820-01987 no backlight when wake up from sleep
                  by kingskie
                  Hello,

                  I have a problem with 820-01987 that has no backlight when wake up from sleep. before there was water damage around U6903 and backlight caps. no corrosion found so i just clean it up. is there any component that in charge for enable backlight after wake up from sleep mode?

                  any suggestion would be appreciated.
                  08-05-2022, 02:51 AM
                • DanPoka
                  Guide me through repairing a Dell p2210f LCD ccfl backlight monitor
                  by DanPoka
                  I bought this p2210f dell monitor to fix. Schematic is the same as p2210.
                  Behaviour is that monitors comes on but then backlight switches off almost instantly. If I look with flashlight I can still find the "No signal message". So definitely a backlight issue. Trying to advance the issue I proved that the protection circuit is switching off the backlight by shorting out C3 and resistor to disable the INL chip then re enable by removing the short.
                  This is where it gets interesting. When I disassembled the monitor to solder leads on c3 capacitor I noticed the backlight flickered...
                  02-15-2025, 05:05 AM
                • Comp_Pro
                  No Backlight Macbook A1990 820-01041
                  by Comp_Pro
                  Hello all,

                  Am trying to figure out this backlight issue with this A1990 Macbook Pro.

                  Tests performed:

                  There is no backlight even with a good screen.
                  Backlight IC is receiving the correct support voltages.
                  Fuse F8400 ok
                  Current sense resistor R8400 ok
                  Backlight IC is receiving 3.3V on enable pin.
                  Backlight IC receiving voltage from PPBUS_G3H, aprox 12.5V.
                  Backlight IC receiving 5V from PP5V_G3S
                  Backlight IC BKLT_SCL and BKLT_SDA both measure 0.545V diode mode to ground
                  I2C_BKLT_SCL and I2C_BKLT_SDA both measure...
                  05-06-2024, 10:23 PM
                • Loading...
                • No more items.
                Working...