A1990 (820-01041) - Touchbar no display / touch

[HeyWatchOutDude]

Hi,

I have here an A1990 - Touchbar doesnt work. (no signs of life)

Note: J5100 was corroded - cleaned it and removed the corrosion. (Flexcable was fine)

J5100 power lines:
- PP1V8_SLPS2RSW_DFR: 1.8V
- PP5V_G3S_DFR_FILT: 5.1V

J5110 power lines:
- PP1V8_SLPS2RSW_DFR: 1.8V
- PP3V3_G3HSW_DFR: 3.3V

Any idea? Is there something i missed?

Note: Sadly I dont have another topcase with a known good TB for testing.

 

[2informaticos]

Check J5100 signals, pins 1, 2, 18.
Also check J5110, pins 10 & 12.

 

[HeyWatchOutDude]

J5100:
- PIN1 "TP_DFR_TOUCH_PANEL_DETECT" : 0.03V | O.L. (no touchbar connected)
- PIN2 "DFR_LID_OPEN_L" : 0.0V | O.L. (no trackpad connected)
- PIN18 "DFR_TOUCH_RESET_L" : 0.05V | 0.466 (no touchbar connected)

J5110:
- PIN10 "DFR_DISP_INT" : 0.0V | 0.470 (no touchbar connected)
- PIN12 "DFR_DISP_RESET_L" : 1.8V | 0.470 (no touchbar connected)

Note:
I have already tried DFU restore - no changes to the touchbar.

Note2:
TPC522 is gone - but connection between R5106 and J5100 / PIN2 is fine.

Note3:
ALS not working - Keyboard backlight is working.

 

[2informaticos]

Please, connect touchbar and found proper test points...

 

[HeyWatchOutDude]

J5100:
- PIN1 "TP_DFR_TOUCH_PANEL_DETECT" : 1.8V
- PIN2 "DFR_LID_OPEN_L" : 1.4V
- PIN18 "DFR_TOUCH_RESET_L" : 0.04V

J5110:
- PIN10 "DFR_DISP_INT" : 0.0V
- PIN12 "DFR_DISP_RESET_L" : 1.8V

(with touchbar and trackpad connected)

 

[2informaticos]

Check these levels with another machine with touchbar.
No need to be exact same model; just compare same touchbar lines.
Also check them in diode mode.

Which pins of J5100 have been affected by corrosion?

 

[HeyWatchOutDude]

I will do.

The following PINs were affected:
- PP5V_G3S_DFR_FILT
- PP1V8_SLPS2RSW_DFR

 

[HeyWatchOutDude]

J5100:
- PIN1 "TP_DFR_TOUCH_PANEL_DETECT" : 1.8V
- PIN2 "DFR_LID_OPEN_L" : 1.4V
- PIN18 "DFR_TOUCH_RESET_L" : 0.04V

J5110:
- PIN10 "DFR_DISP_INT" : 0.0V
- PIN12 "DFR_DISP_RESET_L" : 1.8V

Update: I have compared the values (to a known good board / different model) - same behavior.

I also noticed that " PIN18 "DFR_TOUCH_RESET_L" is during boot like 2-3 seconds on 1.8V then it drops down to 0.04V.

So I guess the board is fine? And just the TB dead?

 

[2informaticos]

Changing touchbar is the best option here.

 

[HeyWatchOutDude]

Ok, what about the ALS issue? (display brightness is not adjusting)

 

[2informaticos]

Test the machine disconnecting camera flex from T-CON board.

 

[HeyWatchOutDude]

TB is now working.
After reconnecting the flex all (TB, camera and ALS) is working again - what the hell?

Edit:
Sometimes it’s working sometimes not.

Edit2:
ALS and camera is always working - TB is now dark again.

 

[2informaticos]

Only lose the touchbar backlight, or touch functions too?
Clean the connectors; be sure to get good contact.

 

[HeyWatchOutDude]

Reflow of the J5100 solved the issue - thanks for your help.