820-00840, No Camera, ALS SMBUS fault. SMC?

SMMRepair

Member
Working on an 820-00840 board that had no camera. Tested it in several assemblies as I know the cameras in these panels love to fail. All power lines measured fine around U3900, but I had seen someone about a year back mention the ALS SMBUS sensor causing issues with the camera SMBUS line, so I pulled R8556/8 and camera functionality returned. So issue was definitely the ALS SMBUS line.

I'd love to repair it "properly" of course, and I imagine the fault lies in the SMC. However, since ALS is tied to the main SMBUS line, I would expect a fault to affect other things as well (high fan, etc) or at least cause an error in AHT, but it didn't. So my question is, would replacing SMC in this case even help?
 

SMMRepair

Member
No ideas I guess? Will just consider this one fixed with the ALS SMBUS resistors removed. Not ideal having keyboard backlight on full-time and no auto-dim of LCD, but it will work I guess. Thanks.
 

2informaticos

Administrator
Staff member
If you doubt between SMC and ALS, just connect the webcam from another LCD assembly.
Resolder the resistors previously removed, of course.
 

SMMRepair

Member
I tested it in several assemblies as noted in the original post. It's a board fault, not a camera/assembly fault. With those resistors removed from the board, camera works in all 3 test assemblies of ours. With resistors in place, camera works on none of them. That's why I was suspecting the SMC. Board's gone now, but hopefully it doesn't cause any issues for the customer; was hoping to maybe get a response quicker than 3 days, lol. All good.
 
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