11 
7 
2 White Screen - External display not detected
I have had this MBP 13" 2012 (2.9 GHz) (Board # 820-3115) sitting on the shelf for awhile now, It boots up and chimes but the display stays white. It has been checked and double checked by our local technician who said that all voltages on the display lines were indeed present, but we only have a white screen with the built in display and when we connect to an external display it is not detected (I believe previously it displayed externally but now nothing). I am hoping that the GPU hasn't failed as we have looked at it under 2 different high definition microscopes and it appears to be in normal condition with no cracks, burns or blemishes. We have tried to reset SMC & PRAM numerous times to no effect. The laptop previously had Catalina installed and has since had a clean installed SSD with Catalina so it can be no issue with the OS. Everything is connected up correctly and we have tried with other known working drive cables. Hoping we have missed something very simple....
Is dit een goede vraag?
@livfe since you have no video at all, it does sound like you are having issues with the PCH. All video output comes from there. Any chance you can post some really well focused images of your logic board with your Question? That way we can see what you see. :-)
door oldturkey03
@oldturkey03 Sure, looking at the Schematics there are quite a few results for PCH. U2652? U2601? ... ? My MS can only take pictures of small areas and would need 20+ images of the full board....
door livfe
@livfe U1800 :-) It would not be to the level of a MS but just a good picture overall will work :-)
door oldturkey03
@oldturkey03 Oh the big boy that would need re-balling or completely replacing... bad news :( & it is on the underside... board out again. I posted a short video as I cvannot get my MS into photo mode... bad day.
door livfe
@livfe why do I think that this is one of those IC's that is running into issues with bad solder bumps. You willing to try to "bake" your board to see if that will yield some result?
door oldturkey03
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