A2485 820-02100 - no image on the screen, but its working sometimes

[adrko]

A2485 820-02100

Never liquid damaged, never dropped, never opened before
No image on the screen 90% of the time.

Basing on observation of backlight intensity:
- ALS works
- backlight works
- I can adjust backlight via backlight keys

Macbook worked fine with external via thunderbolt. Got image to show (3 times) on internal when fiddling with the lid and USB dongle to connect m+kb. Image dissapeared when I reconnected USB device.

Backed up data, and opened mac to check everything. Then I cannot get external to work again.

- have not tried DFU revive/restore yet
- cannot test with known good unfortunately
- could not check if LCD is detected in MacOS
- lid angle sensor looks perfectly fine, I assume its working since trackpad stops working when lid is almost closed.

I'm not able to check LCD voltages, everything is on the other side of the motherboard.
I could try to figure something out if I knew what to test, but right know I have no idea what is responsible for enabling image on the LCD.

Thank you

 

[2informaticos]

Actually no external image at all?
Test disconnecting internal LCD.

 

[adrko]

It worked fine, I know mac is booted to MacOS because I can hear the chime when connecting thunderbolt screen. I will check with hdmi also.

 

[adrko]

Nothing seems to work

Got image on external only when booting to recovery/selection screen by holding power button.
Otherwise it doesn't want to display to external, it used to without issues when I backed up data, not anymore.


Voltages present, backlight is around 12V, same as working A2442

Dont have working lcd to test unfortunately.