820-4924 PPVIN_S4_TPAD missing

ajdoc

Member
Board got liquid damage and there is no trackpad/keyboard.
Tested with good known keyboard/trackpad and trackpad flex.

Board booting fine.

PPVIN_S4_TPAD is missing (no short to ground)

If I understand correct power line for TPAD is created from PPBUS_X239_REG.

Q7979 Measurements with keyboard/trackpad connected
pins 1,2,3 @ 10.95V
pin 4 @ 11.25V
pin 5 @ 0.002V
Resistance on PPBUS_X239_REG, 74.4K, Diode mode 0.505V

Any idea?
 

2informaticos

Administrator
Staff member
That voltage is controlled by SMC_ACTUATOR_DISABLE_L, if R7922 is soldered.

Check SMC_LID signal; must be high.
 

ajdoc

Member
4/Q7979 @ 10.20V
R7970 @ 33K

1/Q7972 @ 0.080V
3/Q7972 @ 10.26V

R7976/22/26 are OK



SOLVED
U8000 was faulty.
PP3V3_S4_P3V3S4FET and P3V3S4_EN was present but 0V on output. Replaced U8000 and all works fine now.
 
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