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820-3115 water damaged green light doesn't turn on

R

rferruses

New member
Hi guys, I have a 820-3115 water damaged that didn't have green light. PP3V42_G3H was shorted to ground. The short was on U7941, I replaced it, and green light came, but didn't turn on. Later I realized PP3V3_S3 was completely short to ground too, I found the short on U2700, I replaced it, and the short disappeared. But I don't still have PP3V3_S3 high. So I looked for more shorts, and I found PP3V3_S0 has low resistance to ground (300 ohms vs 8,75k ohms in good board). When I inject voltaje, there is a draw of 0,85A at 3.3V, and u1800 (pch) seems to become hot.. Does it means I can stop working in this board? I don't have tools to replace pch.. Thank you in advance.


Update: I have tried to inject 3.3V on good board on pp3v3_s0 and u1800 seems to become hot too but only drawing 0,35A.. so maybe it is not the component that is shorted, but I can't find which one is the one shorted. And I don't have a flir cam!
 
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2informaticos

2informaticos

Administrator
Staff member
300 ohms is not short, just low value comparing with good board.
Inject voltage in such case will not help.

The problem is that you had short on several power rails which go to SMC and PCH.
One of them can be dead now!
If you want to continue, must post some signals from startup sequence...
 
2informaticos

2informaticos

Administrator
Staff member
Do you get green light now?
Post SMC_PM_G2_EN, SMC_ADAPTER_EN, SMC_BATLOW_L, PM_RSMRST_L, 3v_S5, PM_SLP_SUS_L, 3V_SUS, S5_PWRGD.
Also check RTC signals and post exact voltage for PPBUS_G3H (no battery connected).
 
R

rferruses

New member
SMC_PM_G2_EN: 3.45V
SMC_ADAPTER_EN: 3.29V
SMC_BATLOW_L: 3.32V (I measured this one on Q5040 and it looks nasty, with green pubs, I'll change it later)
PM_RSMRST_L: 3.27V
PP3V3_S5: 3.33V
PM_SLP_SUS_L: 2.50V
PP3V3_SUS: 3.32V
S5_PWRGD: 3.43V

PPVRTC_G3H: 3.32V

PPBUS_G3H: 12.61V


Yes, I get green light since I removed PP3V42_G3H short to ground. Thank you.

I was wondering why I didn't have 3.3V on pm_slp_sus_l and I changed u7940 and q7822 and now PM_SLP_SUS_L dissapeared.. I don't understand why. I should have this line even with those one removed, shouldn't I?
 
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