Where is the location of the back light fuse 820-3476-a?

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MacBook Pro 13" Retina Display Late 2013

Model A1502 / 2.4, 2.6, or 2.8 GHz dual-core Intel processor / Released October 2013

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allenzabbal @allenzabbal

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Опубликовано: 12 мар 2015 г.

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Where is the location of the back light fuse 820-3476-a?

I recently received a Macbook Pro A1502 Retina liquid spill with logic board number 820-3476-a. Unit boots up but no back light. Does anyone know the location of the back light fuse and wled driver? Crazy thing I had it working fine however when installing the OS back light just went out. Also how many volts should I be getting on pin one?

Thanks

I think this might be the location of the fuse

Ответ на этот вопрос У меня та же проблема

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Post some top and bottom view images of your logic board with your question. Adding images to an existing question

12 мар 2015 г. из oldturkey03

yes F7700 is the fuse

11 янв 2018 г. из joe

its probably fine though, they rarely blow even under liquid damage. start probing U7700 pins 17,18 and 5 what voltages do you have

11 янв 2018 г. из joe

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Post some top and bottom view images of your logic board with your question. Adding images to an existing question — oldturkey03
its probably fine though, they rarely blow even under liquid damage. start probing U7700 pins 17,18 and 5 what voltages do you have — joe

zzz @zzz30021 Репутация: 7,6к zzz 13 22 11 · Answer 1 · 2015-04-17T23:22:19-07:00

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zzz @zzz30021

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This is all wrong. You're talking about buying replacement chips without even having a schematic or a boardview. How can you know what to replace without even knowing where to measure??? How do you know the LED driver is bad?

Get a schematic and a boardview for 820-3476, then answer the following questions before further guessing.

1) Do you have 2.7v to 3v enable signal on pin 17 of U7700?

2) Do you have 5v on pins 5 and 18 of U7700?

3) Is R7733 0 ohms?

4) Is feedback network between R7731 and R7732 functioning properly? Traces to resistors good? Resistors themselves good?

5) What voltage do you have on backlight output, pin 1 of LCD connector? 0v? 12v? 20v? 27v?

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It's never the fuse on these. They are smart enough to turn off in case of a fault state.

17 июн 2015 г. из zzz

I have a question concerning this board I have the same 820 3476 a and I have an amber light all the time with battery or without and no power on can you tell me where to start with this the board looks very clean I had to replace the EFI chip because the board did not have one when I bought it doesn't need flashing how to do that Thank you for your help

24 сен 2015 г. из cyprotech

Hi

I have got 0V on pin 17 of U7700!!!

can you please lead me what should I do?

15 июн 2017 г. из Justin

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oldturkey03 @oldturkey03 Репутация: 782,1к 1,1к 893 2,3к · Answer 2 · 2015-03-13T17:31:58-07:00

oldturkey03 @oldturkey03

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allenzabbal, you are correct. The reference designator is F7700 and it is a 3A 32V fuse in a 0603 package and the driver is U7700 and it is a LP8548B1SQ_-04 IC.

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I checked the fuse and it is not open. Can the wled driver fail without and the fuse still ok? Do you know how may volts I should get on pin 1 on the lvds connector? thanks again.

14 мар 2015 г. из allenzabbal

also where can I get the backlight package LP8548B1SQ? Would a LP8545SQ package work?

https://store.ti.com/LP8545SQENOPB-High-...

Thank you oldturkey03 for your help

14 мар 2015 г. из allenzabbal

zzz AKA Louis Rossmann know his stuff along with oldturkey03

18 апр 2020 г. из Peter Newman

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MacBook Pro 13" Retina Display Late 2013

Where is the location of the back light fuse 820-3476-a?

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