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820-00850 no KBD, no TPAD

A

ajdoc

Member
Customer tried replace battery on his own.

I found one of the UB400 had short on PP3V3_UPC_TB_LDO.
Replaced UB400 and it boot now but no KBD/TPAD

Tried with known good TPAD with flex and same issue.
I found there was no diode mode readings on J6701/17 (TPAD_3V3_SPI_EN).
Replaced U6855 and reading is correct.

There was no diode mode readings on J6701/1 (IPD_LID_OPEN).
Replaced U4802 and have correct reading now.

Still no KBD/TPAD.

Diode mode values of J6700 and J6701 are correct.

Open/close lid sensors work fine.
Touch bar is working as well (display and touch).

Will fit board in to another topcase tomorrow.

Any idea what to check next if there will be the same issue with another topcase with trackpad?
 
2informaticos

2informaticos

Administrator
Staff member
I bet yor problem is trackpad related; keyboard can't work without trackpad.

If still same problem with known good trackpad board/flex, then check all components connected to J6701.
Start with power rails, next check page 65.
 
A

ajdoc

Member
No luck.

When checking voltage to J6701 do I need do it with connecter trackpad?

Found something strange near U6860
R6871/1 have 3.3V but R6870 have 0V and have short (0.001 in diode mode) on R6870/1.
How is that possible? Thats the same line which have R6871/1 which have correct voltage?

Can you check if you have on R6870/1 GND or PP3V3_GS?
 
A

ajdoc

Member
At the end I replaced just in case U6855, Q6861, U6860, Q6862 and keyboard and trackpad works fine now.
 
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