Macbook Pro A1502 No Picture no Backlight

[platinumsteel]

Re: Macbook Pro A1502 No Picture no Backlight

Yo mon2 . You should change your name from mon2 too monster2 lol . haha..Well i got good news and bad. I did exactly as you mentioned and now i have steady 5v on pins 28,29,30 on the LVDS. And i have 49V on pin 1 of the LVDS . I also have most voltage requirements on U7700 with enable pin 17 . But still no image or backlight with screen connected. But i seem to be missing pins 1 and 2 on U7700. I have posted a picture of the voltage am missing. Am not sure if that is normal or it's missing. Hoping you guys can guide me further. Working test screen and stuff would be here at the end of this week. Am not able to rule out a bad screen or cable at the moment. So as piernov rightly said maybe i should wait till i get working tested screen it seems. But all in all having a lot of fun with this so far and happy i am slowly better able to understand how the backlight and picture circuit works on these A1502's

[platinumsteel]

Re: Macbook Pro A1502 No Picture no Backlight

Okay guys. Was finally able to solve the issue with the no backlight or picture on this unit . I got very lucky and don't know how i missed it but was just randomly probing in resistance mode all the pins of the LVDS connector that is supposed to have voltage and realized that pin 5 measured 0.L or open line. Checked with donor board and the resistance measured high. So looked at the resistor R8342 and checked the resistance and it was giving me a high reading and then go to 0.L . So used heat gun to remove it and noticed one end broke off.so it was not connected to allow voltage to pass tru it ..So i replaced it and to my amazement got picture on internal screen.So if u look at the picture below u will notice that pin 5 is connected to the PP3V3_S0_EDP_SW which is also connected to U8310. So i might be wrong but it was preventing that rail from creating the 3v enable signal to power the Backlight Driver.So that is why i wasn't able ot get the enable signal to be present .And as piernov stated it wasn't seeing or detecting the Screen.Also want to thank all involved especially Mon2 who inspired me to try some nice techniques which did help me better learn the entire circuit..So hope this helps anyone trying to figure out a no picture for the Macbook Pro A1502.