Green artifacts on black color 820-2523-B

[RioRio]

Hello,

I have here a MacBook Pro 2009 15" (820-2523-B), were the black color on screen shows green artifacts. When I bend the topcase of the laptop only a little bit, the artifacts disappear and black colors are normal. Very little pressure is necessary. When I release pressure, the artifacts appear again. So I guess it is a cold solder joint somewhere on the board. How can I proceed to identify the cold solder joint? Or would you just reflow the whole board?

 

[2informaticos]

Probably bad video cable, or display.
Check LCD connector solders and try known good LCD assembly.

 

[RioRio]

Unfortunately the problem appears also with a known good screen. On that screen in addition the white color shows pink artifacts. It is a logicboard issue. I attached two pictures with two different screen assemblies.

 

[RioRio]

I wanted to reflow the two Nvidia chips. When I removed the glue around U8000, C8473 also came off. After soldering on a new cap, the artifacts are gone!

 

[RioRio]

Unfortunately after screwing everything back together, the problem returned. Probably it was only gone because the board was still warm when I tested it.
Any ideas how to proceed?

 

[2informaticos]

If reacted to heat, then is GPU (U8000) problem.
Reflow is not the correct solution; it may work for a while.
Buying such an old chip from China is also risky; even listed as "new"...

 

[RioRio]

But the board reacts positive to pressure. There must be a cold joint somewhere.

 

[2informaticos]

Did you resolder LCD connector?

 

[piernov]

Why would you randomly reflow large BGAs for no reason? Good way to make sure to kill the board…
LVDS line issue, often caused by GMUX. Can also be a broken trace elsewhere or a bad LCD connector.

 

[RioRio]

Hi guys. Thank you for your answers!

Yes, I have reworked the LCD connector, with no effect. After that I've tried a reflow of the GPU, which in the beginning appeared to have solved the problem. But it instantly appeared again as soon as I've mounted back the heatsink. Because the heatsink is putting pressure on the board. The problem still disappeared when bending the board a little bit.

I have tested the board outside of the macbook and I could spot an area that reacted to pressure. The image was turning normal only when pressing anywhere in that particular area. But I could not find the exact cold joint. So I decided not to waste too much more time and just to reflow that whole area.

The good news: I've repaired the artifacts. They are gone and also don't come back when I bend the board. But in one spot delamination appeared. It's called "popcorn effect" according to my research. A bubble appeared under one IC close to the battery connector. Now the board is not charging anymore, and I guess it is not repairable. I did this before piernovs answer, and unfortunately he was right, I've killed the board.

I have read that this can appear because of moisture inside the board. But the macbook was stored in my heated apartment at 50% air moisture for over half a year. So I can not imagine how there could have been moisture inside. Would I still have had to dry the board in an oven before soldering? Probably the temperature I've used was too high. I have used 200°C bottom heat and 370°C hot air (Quick 861DW). Which is the maximum temperature that I should use on a board?

I know it was stupid reflowing the whole area, I should at least have restricted only to chips related to the graphics circuit. Sometimes you win, sometimes you learn.

 

[2informaticos]

If the image related problem was solved, you should try to solve the battery issue now.
If the problem appeared between copper layers (inside the board) this may be really difficult.

Is the battery recognized in macOS at least?
Check diode mode to ground (as voltage too) on the SCL/SDA lines of battery bus.
Was the battery working correctly before the reflow?