820-00164 PP5V_S5 1.57v no PCH power

ytesfay80

Member
I have this board that was liquid damaged around by the SMC U6100, and U7501 mostly. I have UC'd the board and replaced U7501 as well as some resistors that were damaged by the SMC.
I am now getting 1.57v on PP5V_S5. I checked for PM_SLP_S4_L and it is showing 0v and not even a pulse when the machine turns on.

Here are some other measurements I got.

SMC_ADAPTER_EN - 0v
SMC_S5_PWRGD_VIN - 3.4v
PM_PWRBTN_L - 0v
PPVRTC_G3H - 3.4v
SMC_RESET_L - 3.4v
PM_SYSRST_L - 0.06v
PM_PCH_SYS_PWROK - 0v
PM_PCH_PWROK - 0v
PM_RSMRST_L - 0.02v
PM_SLP_S5_L - 0v
 

JohnB8812

New member
Yeah we need more things before PCH power. What is your exact voltage on PPBUS? VRTC_G3H and SMC_PM_G2_EN present?
 

ytesfay80

Member
Sorry I forgot to mention those voltages but I get 8.58v on ppbus and 3.4v on ppvrtc_g3h. I will give you the voltage for smc_pm_g2_en in a couple of hours.

SMC_PM_G2_EN - 3.45v
 
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ytesfay80

Member
Sorry I was on my phone and didn't see 2informaticos' post. I did replace the U7501 chip but here are some of the measurements.
Resistance to ground on PP5V_S5 is around 50kohms.
U7501
Pin 12 - 3.45v
Pin 13 - 2.00v
Pin 21 - 3.4v
Pin 22 - 3.3v
Pin 23 - 8.57v
Pin 29 - 1.58v
 

2informaticos

Administrator
Staff member
Remove C7505, C7400 and C4810; still the same?
Also remove L4820; to discard trackpad connector.
Finally remove U7400 AND Q7430; you can cut off trace from pin 12/U7400 instead.
Do NOT power up the board without U7400, when Q7430 is still soldered!!!
 

JohnB8812

New member
Yeah you can try with those caps removed. Just don't power it on with U7400 off the board. Or U7501 for that matter.
 

ytesfay80

Member
Okay I figured out that C7505 was issue had some solder connecting it to the probe point in front of it. I figured they were connected so I didn't bother separating the solder but it is all fixed now.

Thanks guys!
 
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