Macbook pro Mid 2012 820-3115 No Backlight Has picture.

[platinumsteel]

Hi again guys i have a 820-3115-B logic board that has no signs of liquid damage and is working perfectly fine. It has picture but no backlight . I already did all the basic troubleshooting so screens and backlight fuse has all been ruled out as okay.I used a working board which has backlight to compare and diagnose. And in the picture below is the only thing i notice is different. Am not so great with backlight on these boards as yet. So hoping you guys can guide me where to check next or if it's the backlight Driver that is bad and needs to be changed. I have posted a picture of the voltage on working board as u can see
12.54V on pin 1 of D9701 and Pin 2 reads 26.49V Good Board
12.54V on pin 1 of D9701 and Pin 2 reads 12.54V Bad Board
So apparently it's not boosting I could be wrong.

Bad Board


Good Board

[mon2]

Re: Macbook pro Mid 2012 820-3115 No Backlight Has picture.

1) post the enable voltage on pin A3

2) often, the boost regulator ic at u9701 is replaced if the enable is ok.

[platinumsteel]

Re: Macbook pro Mid 2012 820-3115 No Backlight Has picture.

Ok A3_Enable pin voltage reads 3V . But when u say boost regulator at U9701.Can u kindly elaborate on it a bit ? thanks

[mon2]

Re: Macbook pro Mid 2012 820-3115 No Backlight Has picture.

U9701 is most likely defective and needs to be replaced.

LP8550 is a part from Texas Instruments and you can source through Arrow / Digikey / Mouser / AliExpress.

Better yet, order directly from TI :

https://www.ti.com/store/ti/en/p/pro...e-octopart-wwe

Order spares as they are quite small. Lots of youtube videos on topic on how to replace this part using hot air tools. See Louis Rossman or similar.

Take notes on pin #1 of the bga package and where it is on the logic board. You will need some tacky flux for the repair.

Kapton tape is recommended to protect the nearby parts from flying off during the repair. Use low air pressure but high heat to melt the old part. Be very patient and remove the part only when it starts to swim in the flux on its own. Then carefully use leaded solder which is low temp solder as compared to ROHS solder. Apply this solder carefully across each ball pad on the logic board. Then remove this solder carefully using resolder braid to flatten each ball pad on the logic board.

Finally apply flux again and insert a fresh IC to solder in the new part with the hot air gun.

Be sure to watch a few videos a few times to get the idea of the process.

[platinumsteel]

Re: Macbook pro Mid 2012 820-3115 No Backlight Has picture.

Okay thanks a lot for confirming my friend.I will be sure to report back once I get tru it .

[judamex]

Re: Macbook pro Mid 2012 820-3115 No Backlight Has picture.

U9701 is most likely defective and needs to be replaced.

LP8550 is a part from Texas Instruments and you can source through Arrow / Digikey / Mouser / AliExpress.

Better yet, order directly from TI :

https://www.ti.com/store/ti/en/p/pro...e-octopart-wwe

Order spares as they are quite small. Lots of youtube videos on topic on how to replace this part using hot air tools. See Louis Rossman or similar.

Take notes on pin #1 of the bga package and where it is on the logic board. You will need some tacky flux for the repair.

Kapton tape is recommended to protect the nearby parts from flying off during the repair. Use low air pressure but high heat to melt the old part. Be very patient and remove the part only when it starts to swim in the flux on its own. Then carefully use leaded solder which is low temp solder as compared to ROHS solder. Apply this solder carefully across each ball pad on the logic board. Then remove this solder carefully using resolder braid to flatten each ball pad on the logic board.

Finally apply flux again and insert a fresh IC to solder in the new part with the hot air gun.

Be sure to watch a few videos a few times to get the idea of the process.

i have the same problem, replace U9701 and now all its ok. TY

[MtapeK]

Re: Macbook pro Mid 2012 820-3115 No Backlight Has picture.

Hi again guys i have a 820-3115-B logic board that has no signs of liquid damage and is working perfectly fine. It has picture but no backlight . I already did all the basic troubleshooting so screens and backlight fuse has all been ruled out as okay.I used a working board which has backlight to compare and diagnose. And in the picture below is the only thing i notice is different. Am not so great with backlight on these boards as yet. So hoping you guys can guide me where to check next or if it's the backlight Driver that is bad and needs to be changed. I have posted a picture of the voltage on working board as u can see
12.54V on pin 1 of D9701 and Pin 2 reads 26.49V Good Board
12.54V on pin 1 of D9701 and Pin 2 reads 12.54V Bad Board
So apparently it's not boosting I could be wrong.

Bad Board


Good Board

Hello Good Day, I'm Not Sure If im lae to respond here or you have solved your Problem For backlight On Your 820-5115 Board. But i wanted you to check if there is continuity between A5 of U9701 and {pin 2 } of D9701, if there is continuity the feedback line is working fine then the Problem might be your Backlight Driver.

if there is no continuity make sure to run a jumper wire between A5 of U9701 and pin 2 of D9701 it will fix your Problem