[SOLVED]820-3209 Missing PM_SLP_S4_L Headache..

[MOberdick]

I've been staring at this board for a long time now and for whatever reason cannot narrow down what's causing PM_SLP_S4_L to not enable. Received board with no obvious water damage or corrosion anywhere, it actually looks spotless. I do have PPBUS_G3H and a green light on the charger and what I have as a result of further testing so far is PP5V_S5 present, PP3V3_S5_PCH_PWRGD present, and PP3V3_SUS present. I know that the clock circuit is needed as well which I've got readings of 3.3v on pin 2 and 3.3v on pin VDD_RTC_OUT. I'm kinda stuck on where to go from here and was just seeking guidance to what to check next. Thanks in advance!

 

[dukefawks]

Voltages on R1800-03?

 

[MOberdick]

I have 3.3v pin 1 and 2.7v pin 2 of R1800

 

[dukefawks]

R1800-03 means 1800 1801 1802 1803....

 

[MOberdick]

My misunderstanding..

R1801 3.3v pin 1.. 3.1v Pin 2.... 1M Resistance
R1802 3.3v pin 1... 1.2v pin 2... 20k Resistance
R1803 3.3v pin 1 and also 2... 20k Resistance

 

[dukefawks]

I asked for voltage on both sides....

 

[aprendiz]

Could be corrosion under PCH, R1802 and R1800 measure a lower voltage than it should be (about 3V)...
Measure in diode mode red probe to ground on pin 2 from each resistor and report value...

 

[dukefawks]

Problem is on R1802. C1802 is probably leaky, change it.

 

[MOberdick]

I previously replaced R1802 because of the voltage difference but for whatever reason I didnt think to check for a partial short... It was C1802... Thanks Duke!!