MacBook Pro A2141 - Liquid damage partially fixed but internal display not working (external fine)

dodaj

New member
Hi i am a STEM student (not electronics but I have some basics) and I like tinkering with electronics. I have experience soldering but not microsoldering. My friend came to me with his broken 2019 Intel macbook pro and I offered to help saying i'll do what i can. He said some sticky liquid from a desert spilled in his bag and got in through the right side (the one with the touch id). I managed to advance a bit but hit a real roadblock which is why I signed up for this forum. In terms of tools I have access to a multimeter with diode mode, openboardview with the relvant schematics, a microscope, an ultrasonic cleaner, iso 99%, screwdrivers and hot plates. All of these are froms various labs on my campus.

I first tried to turn it on and nothing happened. I decided to open it up and saw that some parts had corrosion on them:
PHOTO-2025-09-25-13-32-25-1.jpg

I tried to clean it manually and saw that and with some iso 99% and a cotton swab and see if it changes anything. Here is the photo after the cleaning:PHOTO-2025-09-25-13-32-25-3.jpg

I then held down the power button. It showed the no battery but the display did light up. However after closing it up the display no longer showed anything even when plugged in. I decided to use an ultrasonic cleaner In which I put warm distilled water and a bit of 99% iso because i didn't have acess to any special solution. When i took apart the board to clean it completely I discovered that another area on the underside of the motherboard had corrosion:
PHOTO-2025-09-25-13-32-25-4.jpg
After putting it through the ultrasonic cleaner (both sides for multiple minutes) the board seemed more or less clear of corrosion, i dumped it in alcohol and moved it around for a bit then let it dry for a few days:
PHOTO-2025-02-17-18-06-31.jpg
After it was dry I put it back together (replaced the thermal paste). And tried turning it on. I had no display but the caps lock did light up. I used a usb-c to hdmi to plug it into an external display and got the question mark folder. I managed to restore it over the wifi connection and then it booted into the os. My friend logged in and recovered the files. It now boots fine. The only problem is that the internal display doesn't work, and I am stuck trying to fix it. I tried investigating the J8500 with the multimeter but wasn't even sure what to measure. I think the problem might be related to U9850 since a lot of gpu connections seem to go through there but obviously I don't really know what I'm doing so I am very likely wrong. One thing I can say is that the internal display is fully black, so i don't think it's a backlight issue, at least not solely. I found this forum and decided to sign up and post this thread in hopes of getting some guidance.
 

2informaticos

Administrator
Staff member
First of all, welcome to the forum!

Check diode mode to ground on pins 1 & 3 of J8500; w/ and w/o LCD assembly connected.
 

dodaj

New member
Sorry for the late reply, here are the readings.
With and without the LCD plugged in i got the same readings.
EDP_INT_AUX_N (pin 1): 0.640
EDP_INT_AUX_P (pin 3): 0.641

Here is how the LCD was connected when i took the second set of measurements:
lcd-connect-top.jpglcd-connect-bottom.jpg

Also, a while back (after the ultrasonic cleaning) i accidently screwed the bracket holding the lcd connection badly and broke something that degraded over time and now completely came off. Is this bad? can i just superglue it back on?
broke-2.jpgbroke-1.jpg
 

dodaj

New member
Is the T-CON board what i showed in the second photo? The board near the display seems to be fine aside from the screw support the is ripped.
As for a good LCD, i don't have one on hand. I could ask someone else to lend me their Mac maybe, but isn't there some other testing I can do before just switching the display?
 

2informaticos

Administrator
Staff member
When the bracket was ripped off, could damage closer traces; check that.

Do you still get image, only missing backlight?

Backlight circuit is very sensitive to moisture.
But you can waste the time trying to find a problem in the MLB, if the real culprit is the LCD assembly.
 

dodaj

New member
I get no image at all, correct me if i am wrong but if it was just the backlight i think I would still see an image but with very low brightness.
Here's a photo of the LCD connection (screen side). I can see some copper but i am not sure how damaged it is. If you think it's necessary I can borrow this macbook model from someone and test with their working LCD. Supposing the T-CON board is broken, can I get a replacement?
 

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2informaticos

Administrator
Staff member
Do you get 3V3/5V_S0SW_LCD voltages?
Check if pulse at least in the first seconds (when hear the chime).

BTW, ALL image/backlight voltages MUST be checked with LCD assembly connected!
 

dodaj

New member
How do i check while turning the PC on? The board is fully out of the chassis when testing the pins on J8500 so i cannot turn on the PC. Is the setup in the pictures i sent wrong?
 

2informaticos

Administrator
Staff member
Board MUST turn on by itself out of shell.
ALL MacBooks automatically turn on when charger is connected and battery not present.

Only need to connect LCD assembly, for mentioned tests.
 
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