Missing P5VS4RS3_EN

Macbook Air not turning on
Liquid damage on U7600, Chip replaced but Still not power.

PPBUS_G3H 8.55V
PPBUS_S5_HS_COMPUTING_ISNS 8.54V
PPBUS_S5_HS_OTHER_ISNS 8.54V
PP3V42_G3H 3.42V
PPVRTC_G3H 3.31V
PP5V_S5 5.0V
PP5V_S4RS3 0V Missing this Power Rail

PP3V3_S5 3.31V
PP3V3_S4 0V
PP3V3_SUS 3.31v
PP3V3_S3 0v

What step should I take next
 
yes it was corroded and replaced u7600, also Resistor Replaced R8185, No liquid spot found or corrosion anywhere else on board, U1900, U1950, U6100 Checked properly no corrosion.
Can somebody also explain. I am getting 3v on L7560 but not 5v on L7520. I did replaced U7501 but not sure when it should turn on, I am missing PP5V_S4RS3
what is the sequence for to turn on U7501
Sorry if this is not related to post
 

2informaticos

Administrator
Staff member
Check PM_RSMRST_L.
Also check if PM_PWRBTN_L reacts triggering SMC_ONOFF_L signal.
If yes, PM_SLP_S4_L should pulse too.
 

2informaticos

Administrator
Staff member
No need o-scope usually.
Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L signal.
Do it repeatedly, using R5115/16 pads; no need to connect keyboard.
This method is already explained on the forum, many times...
 
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