820-01700 Touch bar not working

[No-Clean]

Clean board, working top case/touch bar tried and same problem.

Diode on J5100:
SPI_DFR_MISO_R 0.480
SPI_DFR_CLK 0.460
SPI_DFR_CS_L 0.485
SPI_DFR_MOSI 0.85

Voltages:
SPI_DFR_MISO_R 1.7V
SPI_DFR_CLK 0V
SPI_DFR_CS_L 0V
SPI_DFR_MOSI 0.400V
I2C_DFR_SDA_R 1.8V
I2C_DFR_SCL_R 1.8V
DFR_TOUCH_INT_L 1.7V
DFR_LID_OPEN_L 0V
DFR_TOUCH_RESET_L goes to 1.8V for about 5 seconds after I plug in the charger then drops to 0.038V
PP1V8_SLPS2RSW_DFR 1.8V
PP5V_G3S_DFR_FILT 5.1V

PP3V3_G3HSW_DFR 3.3 V

R5103 is good

 

[2informaticos]

Any history available, liquid sign on the board, or case?

Did you try DFU mode?

 

[No-Clean]

Mac comes from another shop no history given.

Mac turns on and all works fine, but no touch bar image or touch function, touch bar options are not available under system preferences.

Tried DFU revive option and no luck.

 

[2informaticos]

Save info, if needed and try restore...

 

[No-Clean]

Restored in DFU, then reinstalled Catalina, same problem.

 

[2informaticos]

Keyboard backlight and ALS in working condition?

Check GPIO Source Termination resistors (page 47), DFR related.

"DFR_TOUCH_RESET_L goes to 1.8V for about 5 seconds"
Check the test point for TP_DFR_TOUCH_PANEL_DETECT at same time.

 

[No-Clean]

DFR_TOUCH_RESET_L goes to 1.8V for about 5 seconds with or without TB connected
TP_DFR_TOUCH_PANEL_DETECT stays at 1.8V when TB is connected and MBP is turned on

 

[2informaticos]

Did you check the 20 ohm resistors?

 

[No-Clean]

R4866
R4855
R4856

All look good and measure 20 ohms each

 

[2informaticos]

"Keyboard backlight and ALS in working condition?"

 

[No-Clean]

Sorry to waste your time mate, I'm not having a good week.

Keyboard backlight works, ALS I feel dumb but if that refers to the automatic sensor for screen and keyboard brightness then that is working fine.

 

[2informaticos]

You may expect knocked off (or ripped) components; not strange if machine came from other service.
T2 may be damaged also.
DFR_TOUCH_RESET_L should stay high.

 

[No-Clean]

Found the problem, TPC507 lost connection to L5111 but there were no visible clues and all looked perfect, thanks for help.

 

[2informaticos]

Glad to hear is solved.
Thanks for solution feedback.
Not usual problem, maybe never reproductible, but points one direction to check in future repairs.

BTW, can you confirm if DFR_TOUCH_RESET_L stays now high?

 

[No-Clean]

Thanks, touchbar is working but customer wanted computer quickly and its out the door, when I get another in I will check and report back.