820-00928 2017 A1707 with no camera/ALS

sekidata

Member
No. That’s how I knew that the ALS wasn’t working. No screen dimming and no automatic keyboard backlight.
 

2informaticos

Administrator
Staff member
Camera and ALS not working at same time, should point to power failure; as both use the same power rail.

Did you change the small video cable?
Check if 5V appears on the corresponding point of T-CON board.

May also have problems with U3900.
Check its power and reset.

L4002/3 have good continuity?
 

ipetro

Member
Just a note, most often the problem is either in the camera cable or the camera module: it’s easy to check, you just need to take a broken A1707 display (possibly even from 1708) and connect the camera cable to the display board and the camera with the sensor on the broken display is 99.9% always working. but 100% of 1990 the camera and light sensor do not work, only the picture if 2018 and 2019 will not work at all. This is my experience and should not be taken as a call or recommendation. )
 

sekidata

Member
I did replace the small video cable. Camera 5V does appear on the T-CON board. L4002/3 have good continuity.
 

sekidata

Member
Good to know about the A1990… thanks. I did find an old A1708 display and plugged in its camera flex cable to the T-CON board. I was fully functional. Ok, mystery solved. The original display has a bad camera.
 
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