820-3662 no keyboard backlight.

BCN_Techs

Member
I dont have LP8548B1SQ_-03 but jave LP8548B1SQ_-04 put it and lcd backlight is gone now, keyboard backlight still not working. DO you know if 03 and 04 are compatible?
 

BCN_Techs

Member
What is ALS?

swapped from 820-4924 (04 version) and backlight on display is back, but still no on keyboard. Its nightmare this board.
 

BCN_Techs

Member
I found donor with U7701 Rev 03 version. Put it. Now when it boot while bing keyboard light flashing once. but after that it doesnt turn on again,
 

2informaticos

Administrator
Staff member
Seems that KB backlight circuit starts and overload is triggered.
Check again signals corresponding to KB backlight section.
Change all caps and L/D7720.
 

BCN_Techs

Member
I checked it again and nothing can be found. I removed wire and put back R7747 and now again not blinking.


al caps: C7724/25/23/26/27/20 has been changed. L7720 and D7720 also changed today (before your message)
 

BCN_Techs

Member
changed L7720 again and now it is working. i dont know exactly if it was just l7220 because i also changed U7701 again. Anyway i am sure that l7220 had continuity and there was 5V on both pins. Even if it was so may coil fail?
 
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2informaticos

Administrator
Staff member
I remember a friend who I helped online few months ago.
He had a problem with trackpad movement on 820-2915 board.
18.5V is required to work and he changed all in the corresponding area.
ALL, except L5801; guess which was the problem...
 
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