A1278 820-3115-B Screen Turns Off When Lid is Open

Hi everyone.
A customer brought me a A1278 macbook pro with a screen problem. We found out that LVDS cable needs to be replaced and done it. But now the screen goes off when we open the lid and it turns on and stays on when we close the lid.
I have searched on internet and found too many articles and videos about flexgate off 2016 Macbooks but nothing about A1278.
So definetly need some help to find out where to look or check.

Thank You.

-Emre
 

2informaticos

Administrator
Staff member
Check if LCD image stays on disconnecting BIL (J6955).
Then check SMC_LID signal, w/ and w/o BIL connected.
 
Check if LCD image stays on disconnecting BIL (J6955). = No it goes again.
We have checked the SMC_LID signal with BIL connected and we measured 3.4V, and without BIL it gives 0.003V (around) (I have checked SMC_LID signal without screen connected)
 
Last edited:

2informaticos

Administrator
Staff member
The pull-up resistor for SMC_LID is on the MLB (R5071).
You MUST get 3V, when BIL is disconnected.
If not, remove C6951/55 and check again.
 
We get 3V w/ and w/o BIL connected from R5071. But please correct me if I am wrong do we need to measure these voltages when screen connected or not? I do really not have any knowledge about this. So please bear with me while answering my questions as I can be called as a newbie in this repairing motherboards of macbooks. But I promise you to get all you tell me and will never ask the same things again :)

Thank you

-Emre
 

2informaticos

Administrator
Staff member
No matters if LCD present, or not; SMC_LID must be high.
In previous post you've said not present without BIL (0.003V).

Connect back BIL and post SMC_LID level when lid is open/closed.
 
I have connected the screen and BIL and when the lid is closed I get ~0.003V from the second leg of R6961 which is on SMC_LID. And when I open the lid I get 3.4V from the same leg.
 

2informaticos

Administrator
Staff member
That's correct.
Still same problem with image?
L9004 voltage disappers?

Do SMC reset.
Also 2-3 times PRAM reset, just in case...
 
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