820-00165, No Power, Green Light Present

SMMRepair

New member
Working on a board that had liquid, but was cleaned "hard" by someone; i.e., it looks like it's gone through either 2-3 cleanings (lots of white scaly buildup on everything), or maybe a long cleaning (5-10 minutes) in an UC. I can still spot tiny indications of where the liquid was, but I'm pretty stumped by this one. I have some questions about diagnosing this:

1. This board has ppbus_g3h (8.56v), 3v42 (3.44v), 3v3_s5, 5v_s5, S5_PWRGD (at R8141), ppvrtc_g3h, etc.

2. Board is missing 3v3_s0, 5v_s0, etc. All S0 rails are missing, so board isn't getting to s0 of course.

3. On U7501: pin 4: .197v; pin 12: 3.42v; pin 21: 3.42v; pin 23: 3.3v. So I'm missing my EN1 (P5VS4RS3_EN_R) for U7501. Tracing this back...

4. PM_SLP_S4_L is .201v and S4_PWR_EN is 0v. I believe these are both sent out at the same time, which means something earlier is likely missing...

5. Found I'm also missing PM_SLP_SUS_L as well, but I do have PM_DSW_PWRGD (3.42v), so sounds like my SUS signal is my issue here...(uh oh, hopefully not dead CPU!)

6. At U8130: pin1 is present (3v3_s5), but I don't have PP3v3_SUS. Looks like this is required before PM_SLP_S5_L, even, so I believe we need to start here, right?

7. Looking at p3v3sus_en...I've got 0v at both pins of R8190. So now I'm missing p3v3sus_en and PM_SLP_SUS_L, which is where I get stuck. Really hoping it's not a dead CPU. Maybe a clock issue? No signs of liquid near clock, and my vrtc is proper, but maybe it's damaged anyway.

I replaced U8130 to be safe, and no change. Still no pp3v3_sus, etc.

I think I've offered enough information on this one, but if not, please let me know. Seems I need to get my PM_SLP_SUS_L situated first. If this is not correct, please let me know! Thanks, Duke and Aprendiz.
 

dukefawks

Administrator
Is it power cycling? Checked 32KHz from clock chip? Checked all rails for shorts? The usual corroded resistors around U6100 and the traces there.
 
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