820-00923 - touchbar maybe

[thomamagic]

hello
i have replace screen for this model. After machine start in recovery and i have message need updating but impossible
normally it's touch bar, i have replace with 3 touchbar and new original flex cable and same
i have test fpc connector and see line DFR_TOUCH_INT_L to gnd
on schematic i see R4485 but no stuff and line go to U3900
you think need replace U3900 or other idea?
Before in other machine i have see problem mainboard when screen have remove but on this not see this problem
Thanks for your help

 

[2informaticos]

Check if boots in safe mode.

 

[thomamagic]

yes working in safe mode

 

[2informaticos]

Tested with another good LCD assembly?
ALS may affect touchbar.

 

[thomamagic]

Yes same, i have put another same and with the original broken same too

 

[2informaticos]

Something could get damaged in the replacement process.
Check around all screw holes and connectors.

DFR_TOUCH_INT_L is shorted to ground even with touchbar disconnected?

 

[thomamagic]

No see damaged after replacement
Yes with touch bar disconnect the line DFR_TOUCH_INT_L is shorted to ground

 

[2informaticos]

Ooops, that points to bad T1.

If you are lucky enough, may be only bad J4402.
You can inject until 2V there, for test.

 

[thomamagic]

i have remove J4402 and same short, i need inject without J4402 ?

 

[2informaticos]

Yeah, better...