macbook pro 820-2914-A - no image / no backlight

Collapse
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • cruiser_
    Senior Member
    • Nov 2019
    • 124
    • Ireland
    #1

    macbook pro 820-2914-A - no image / no backlight

    hi,
    i am working on this macbook pro that had amd gpu shorted.
    it now chimes and boots but there is no backlight.
    Can't see an image with a flashlight either...

    I tracked it down to:
    - No LCD_PWR_EN - u9600 enables
    - No LCD_BKLT_EN - u9600 enables
    - No EG_BKLT_EN from
    - No EG_LCD_PWR_EN

    I forced EG* signals to 3.3V but am still not getting signals from U9600.
    U9600 has all three power inputs (PP3V3_S0, PP1V8_S0, PP1V2_S0).

    LCD_PWR_EN is not pulled down by Q9607 (GMUX_S3_PD_GND above 2V).

    what does the gmux chip need to output LCD_*EN signals?
    what else to check before I go forcing these?
    Last edited by cruiser_; 12-27-2022, 01:39 PM.
    Tags: None
    Previous template Next

    Related Topics

    Collapse
    • baglaivlad
      MacBook Pro A2289 (820-01987-A) No boot/image, but boots to DFU
      by baglaivlad
      Hi everyone. Just a reminder I am not a professional repair technician, fixing Apple electronics is my hobby.

      Recently got my hands on MacBook Pro A2289 with interesting behavior. Pristine condition, no water damage, no visual issues whatsoever. It has no image, no CapsLock, no life except the fan is spinning. But it is able to boot into DFU and recognized by another MacBook. I tried to revive and restore the laptop, but the process ends when the MacBook usually should show an Apple logo with a progress bar. I assume the main power lines and T2 are working. It seems like the Intel...
      01-09-2024, 09:55 PM
    • Madoy104
      Macbook Pro A1989 - No image, working fine with external monitor
      by Madoy104
      Hi everyone,


      I have a MacBook Pro A1989 that was likely exposed to liquid. It doesn't display an image on the built-in screen, but the screen is backlit (you can't see the Apple logo or any other elements when held up to light). The laptop provides 20V and 1.5-2A, and it works fine when I use it with an external monitor. Currently, the connector for the display (J8500) is disconnected. I'm writing to ask for help in diagnosing the issue. I've heard that when the J8500 is exposed to liquid, the processor pin responsible for the display might short-circuit, and I'd like to know...
      08-15-2024, 10:01 AM
    • envym
      MacBook Pro 2018 with Activation Lock
      by envym
      Hi everyone!

      I have a 2018 MacBook Pro (with Sequoia OS) that I've been using for years with no problem. I recently received an M2 MacBook Pro so I'm mostly using it and not the 2018 one, but since a friend of mine needs a computer, I thought I could restore my 2018 and give it brand-new-like to my friend.

      I tried using the built-in tool to restore the MacBook (Settings > General > Transfer or restore > Delete) but it got stuck when trying to remove the Find Device configuration (it asked me for the password for my old Apple ID -now I use the same account but...
      06-27-2025, 08:54 AM
    • arevut
      Macbook Air 2020 13” model: A2337 backlight is on but no image
      by arevut
      Hi all! MacBook Air A2337. There are no traces of liquid or obvious damage, the motherboard is visually in perfect condition. The image is displayed on the external screen, but only the backlight works on the internal screen. There is no image, and the camera on the built-in screen does not work. How to exclude during diagnostics that it is the screen that is broken and not the motherboard? What signals should be present on the connector with the screen removed and connected?
      02-07-2024, 08:07 AM
    • Roccolade
      Macbook Pro 820-01814 no image or backlight
      by Roccolade
      Hi! I'm a bit new to this whole repair world. But this is what i'm working on:

      A Macbook Pro A1990 (820-01814) from 2018. It has no image – or backlight for that matter.

      No history of liquid spills or anything. It's fully functional on external monitor - and the webcam works.. But it doesn't seem like the internal display is even detected.

      Sometimes the backlight lights up, when booting into recovery mode. (No image still)
      That's the only progress I've gotten.

      I tested the panel on another Macbook, and the display worked perfectly....
      03-07-2023, 05:29 AM
    • Loading...
    • No more items.
    Working...