820-00239 No power. PPBUS shorted

Hello. I got another 820-00239 that is not liquid damaged but just randomly stopped turning on. It was taking 20v 0.03a when I first plugged it in and I found that PPBUS_G3H was .230v and .032 in diode mode. I checked for the same value on all big coils and found that L8050 was also .032 in diode. I replaced U8050 and PPBUS was no longer shorted anymore but it still will not turn on. Now I have 20v 0.04a and seem to have all S5 voltages but nothing on any S4. I can't seem to find anymore shorts so not sure where to look next. Here are some voltages I took.

PPBUS_G3H - 13v
PP3V3_G3H - 3.3v
S5_PWRGD - 3.3v
PP1V8_S4 - 0v
PP5V_S4 - 0v
PP3V3_S4 - 0v


Staff member
PCH got an overvoltage on PPVCCPRIMCORE_SUS_PCH power rail; it could be dead now.

Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L.
If present, check for pulse at any PM_SLP_Sx_L signal at same time.
Ok so I am actually missing PM_SLP_S5_L but I have PM_SLP_SUS_L. I triggered SMC_ONOFF_L and PM_PWRBTN_L does drop but PM_SLP_SUS_L does not. Should I replace U7800 or is this a CPU issue?


Staff member
PM_SLP_SUS_L must stay high, if charger is connected.
Didn't chek the other mentioned signals for pulse???

Also check PM_RSMTST_L if steady high.
PM_RSMTST_L is steady 3.3v
PM_PWRBTN_L is 3.3v but does drop when I trigger SMC_ONOFF_L
PM_SLP_SUS_L is steady 3.3v
All other PM_SLP_Sx_L signals are 0v and do not react at all when I trigger SMC_ONOFF_L


Staff member
Looks like dead PCH, sorry...

You can still check the RTC signals, PM_DSW_PWRGD, PCH_INTRUDER_L, PM_BATLOW_L.
Damn that's what I thought. I checked PM_DSW_PWRGD and PM_BATLOW_L are both steady 3.4v and PCH_INTRUDER_L is 2.8v. Thanks.