820-00928 2017 A1707 with no camera/ALS

[sekidata]

Customer states that this A1707 machine experiences intermittent keyboard glitches. Inspection showed nothing strange and no liquid damage. However, camera and light sensor are nonfunctional.

I verified that the ferrite bead L4004 is good, PP5V_S0_ALSCAM_F is at 5.1V, and the I2C data lines for camera/ALS are pulled up correctly. What else can I check to bring camera and ALS back? Could there possibly be a connection between keyboard issues and camera?

 

[2informaticos]

Keyboard backlight is ALS dependant.
Test another screen, with known good camera/ALS assembly.

 

[sekidata]

I don’t have a display this old. I assume A1990 is not compatible?

 

[2informaticos]

It should work for test at least.

 

[sekidata]

Ok, connecting a newer A1990 display did not restore camera functionality.

 

[2informaticos]

What about KB backlight and ALS?
Screen backlight reacts directing flashlight to the ALS?

 

[sekidata]

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

 

[2informaticos]

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]

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]

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

 

[sekidata]

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.