M1 Air 820-02016 - no backlight

[overshoot]

Hello,

I have this board which my personal board used for test and I screw it up while testing a display not fully assembled in the case.
I saw a spark near the CD3217 if I recall well and that was it.
Now I can tell I have the 5V and 3.3V lines to power the screen and also, when the screen is not plugged, the external video will work however it acts as a secondary display, not the main one.
I have inspected the board and haven't seen any blown part.
The backlight enable signal is not on when the screen is plugged in.

Is there any other signal that I can measure in order to narrow down the faulty component please?

 

[2informaticos]

Check diode mode to ground on JP600 data lines; pay atention to pin 1.

Do you get 1.8V at pin 4?
Pin 6 goes high to 3.3V?

Of course, check with good LCD connected.

 

[overshoot]

JP600 Diode mode measurements:
Pin1: 0.26
Pin2: 0.545
Pin3: 0.565
Pin4: 0.535
Pin5: 0
Pin6: 0.31
Pin7: 0.3
Pin8: 0
Pin9: 0.295
Pin10: 0.31
Pin11: 0
Pin12: 0.31
Pin13: 0.295
Pin14: 0.3
Pin15: 0.295
Pin16: 0.31
Pin17: 0
Pin18: 0
Pin19: 0.31
Pin20: 0.58
Pin21: 0.295
Pin22: 0.58
Pin23: 0
Pin24: 0.51
Pin25: 0.295
Pin26: 0.52
Pin27: 0.295
Pin28: 0
Pin29: 0
Pin30: 0.546
Pin31: 0.35
Pin32: 0.547
Pin33: 0.35
Pin34: 0.547
Pin35: 0
Pin36: 0.545
Pin37: 0.38
Pin38: 0
Pin39: 0.38
Pin40: OL
Pin41: 0
Pin42: OL
Pin43: 1.13
Pin44: 0.49
Pin45: 0.54
Pin46: 0.28

Pin4 goes to 1.8V steady and Pin 6 goes to 1.15V
LCD works with another board. I've tried a different screen with the faulty board and same thing.

 

[overshoot]

Pin3 seems off.
Is it what I think it is, a bad CPU like on the 820-00923/820-00239?!

 

[2informaticos]

"Pin3 seems off"
What do you mean?

Pin 1 seems to be affected.
Pins 1 & 3 must give the same reading in diode mode.

Looks like bad CPU...

 

[overshoot]

Yeah, checking with the measurements I find on Flexboardview, Pin 3 is off compared to the rest.
I guess that one will become a MacMini.
Thanks for your help.