820-00239 touch on touchbar not working.

BCN_Techs

Member
The board was "checked" by other technician and there was overheat on touchbar's touch flex componentes (under metallic protection.) and touchbar wasnt working at all. I bought touchbars and now touchbar gives image but touch is not working. Checked J442 and seems to be ok.

Checked J4402 for an kind of short to ground (with board off) and there is no short. Seems that touch is managed by U3900, is that right? What can i check?
 

2informaticos

Administrator
Staff member
You must check basic signals and voltages at J4402, with Touchbar connected.
Pins 1, 2, 15,18, 20, 21, 22.
Also check all SPI TERM resistors from page 42.
 

BCN_Techs

Member
Pin1 - 1.76V
Pin 2 - 0.37V
Pin 15 - 0V
Pin 18 - 0.17V (R4481 is ok and there is 1.8V on other side)
Pin 20/21 - 1.8
Pin 22 - 5.1V


changed q4400 and now get 5V on Pin 2 and 1.8 on pin 18. BUT there is problem. I think T2 is "protecting" mac and now mac is asking for critical update to continue working, when try to update it gives me error . I can only boot in safe mode but touch not working (no image). Already tried reinstall but no changes

Have you faced that before?
 
Last edited:

BCN_Techs

Member
I am trying all that with board out and with externel display.

You mean webcam from lcd assembly board?


Anyway before repair when i start mac with board out it was taking much less time to arrive login display. Now it can easily take about 3-5 minutes.
 

BCN_Techs

Member
I checked it and disconnected touchbar, camara, touch id and same result.

The problem now is that i dont get even image on touchbar. I cheked J4401 and seems ok. Than i saw that L4401 was moved (probably by me when was working on Q4400. Repaired it and get about 0.4V on both sides.

Couple days ago i repaired machine with same issue, and there was touchbar problem. Once i solved it ( some small components it started normally.


2INformaticos What i must check for J4401 to check why i am not getting image on touchbar?



P.S. Just reinstalled completly clean version of 10.15 and same result. So i guess there must be something wrong with touchbar touch or image lines on logic board?
 
Last edited:
Top