820-01700 no image

[macfixer]

No image on internal or external
Dont have new internal display to test with
Target mode gives me "disk is not readable"
DFU restore and revive went through but no change to image
Touchbar doesnt work

Board is carefully inspected, GPU dye itself too
No idea where to start on this one, never had no image on a 16" before

Edit: it seems to "boot", it chimes and gives usb activity

 

[2informaticos]

Any history available?
Did you test external video disconnecting internal LCD?

 

[macfixer]

No history, customer tells us it just stopped working

Yes internal is disconnected when we try external, we have now also tried replacing display with a used original known-working one as well

Edit: it was bought aprox. a year ago

 

[2informaticos]

Looks like GPU problem; check if it gets all voltages.
You can try changing U9850; it normally affects only internal video.
Just in case, check diode mode to ground on EDP_INT lines, corresponding to J8500.

 

[macfixer]

Ive checked voltages and they seem fine.

UA600:
VIN=12.9v
VCC=5v

UA000
PP1V8_S0_GPU=1.8v
PP3V3_S0_GPU=3.3v

I noticed the area to the left of GPU is getting up to 50c hot, while GPU is lukewarm in comparison

 

[macfixer]

 

[2informaticos]

What about LA730/40 voltage?

 

[macfixer]

0.7V on all 4 coils in that space

 

[2informaticos]

"Just in case, check diode mode to ground on EDP_INT lines, corresponding to J8500."

 

[macfixer]

EDP_INT_AUX_N=0.418
EDP_INT_AUX_P=0.419
EDP_INT_ML_N<0>=0.358
EDP_INT_ML_P<0>=0.355
EDP_INT_ML_N<1>=0.356
EDP_INT_ML_P<1>=0.355
EDP_INT_ML_N<2>=0.356
EDP_INT_ML_P<2>=0.356
EDP_INT_ML_N<3>=0.357
EDP_INT_ML_P<3>=0.355

 

[2informaticos]

Nothing strange there.

Missing internal/external video at same time, points more to internal GPU problem.

 

[macfixer]

Alright thanks for the pointers!

I do have a donor board here, might attempt replacing the gpu