MacBook A1707 A-00928 stuck logo

ipetro

Member
No traces of flooding or damage were found under a microscope (. Tell me in what direction to start diagnosing?
 

ipetro

Member
Found that PP0V9_TBT_X_SVR is in a short circuit. Is it the U2800 that is faulty? and could this be due to the fact that the MacBook does not boot and the image is not displayed on the built-in display?
 

2informaticos

Administrator
Staff member
Strange to have damaged thunderbolt chip after changing thermal paste.
If there is pure short, you can inject voltage and see what gets hot.

I expect mechanical damage, caused by wrong manipulation.
Do you get 3V3/5V_S0SW_LCD?
 

ipetro

Member
PP3V3_S0SW_LCD=3.3v
PP5V_S0SW_LCD=5v
Perhaps the short circuit was and not a consequence of replacing the paste. As I understand it, the PP0V9_TBT_X_SVR line is responsible for outputting the image to an external display, since the external display does not work through this side. it works through another.
 

2informaticos

Administrator
Staff member
You can't get image; LCD isn't recognized by PCH.
Check diode mode on all EDP_INT lines of J8500.

Just in case, test with known good LCD assembly.
Also change the small video cable, connected to MLB (J8500).
 

ipetro

Member
I conduct tests on a working LCD; it works well with another working board. all EDP_INT indicators are normal and the same as on the working board. I don't see any deviations. I installed the cable from my work MacBook and nothing happened, and there was no backlight.
 

2informaticos

Administrator
Staff member
Missing DP_INT_HPD implies missing image.
Then you can't expect backlight!
There is no reason to bother with backlight circuit in this case.

Inspect around heatsink's screw holes for damage.
Be sure U9850 area isn't affected.
 

ipetro

Member
my EDP measurements
EDP_AUXCH_C_NDefaultd0.408
EDP_AUXCH_C_PDefaultd0.409
EDP_BKLT_ENDefaultd0.495
EDP_IG_BKLT_ENDefaultd0.560
EDP_IG_PANEL_PWR_ENDefaultd0.559
EDP_INT_ML_N<0>Defaultd0.350
EDP_INT_ML_N<1>Defaultd0.348
EDP_INT_ML_N<2>Defaultd0.349
EDP_INT_ML_N<3>Defaultd0.350
EDP_INT_ML_P<0>Defaultd0.348
EDP_INT_ML_P<1>Defaultd0.349
EDP_INT_ML_P<2>Defaultd0.350
EDP_INT_ML_P<3>Defaultd0.349
 

ipetro

Member
I replaced the U2800 and the MacBook worked. But an external monitor is not useful for running the display. everything works, even sleep. works well until you reboot. It seems to me that there is a problem with switching graphics since the Mac cannot turn on the display on its own until loading starts on the external monitor.
 
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