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820-00045 - DCIN stuck at 5.21V 65mA

J

jadao

Member
This board has no liquid damage, usb meter shows that dcin is set to 5.2V at 0.065A witch means no negociation with SMC.

PP3V3R3V0_AON is missing (0V), 0.306 in diode mode and resistance to ground is 600 kOhms

PP3V3_G3H is missing (0V), 0.359 in diode mode and resistance to ground is 82kOhms

Since I have no short on PP3V3R3V0_AON I don't think replacing yet U4700.

I am tempted to replace U7100 because it's creating PP3V3R3V0_AON. However, I am not sure what other signal needs to be present for U7100 to create PP3V3R3V0_AON. Also I don't know if PP3V3_G3H is my first concern or my second...


Btw, I know how CPU will end up on this board:)
 
J

jadao

Member
Yes I do measure 5.22 V on PPDCIN_G3H and PPDCIN_G3H_CHGR.
CHGR_ACIN voltage divider is working and I get 1,32V.

I found out SMC_RESET_L at 0,22V.
R7160 is ok at 100kOhms and I get 0,22V on both sides of this resistor.
No short, in diode mode, I get 0,720 on SMC_RESET_L and 0,568 on SMC_RST_L.

Waiting for donnour boards will try to replace U7100...
 
J

jadao

Member
I received donnour boards and replaced U7100, now the board is power cycling.

PPDCIN is spiking to 5.21V and PPBUS is spiking to 8.16V
SMC_RESET_L is now spiking to 3.3V
PP3V3_G3H is now spiking at 3,3V
PP3V3R3V0_AON is also spiking to 3,3V

I really have no other idea what to look next, if it's again a bad u7100 or something else messed.
I can still replace U7100 with another one but power rails and signals changed compared with old u7100 and want to make sure before wasting a lot of time.

I noticed batch code are not the same but u7100 come from same 820-00045 can this also matter?

Defect board had this marking on u7100:
95530
B506BH

Donnour board U7100
95530
B449AJ

Thank for any tips.
 
2informaticos

2informaticos

Administrator
Staff member
Should be good if really comes from 00045 donor board.
Try to start in SMC bypass.
Check if all PM_SLP_Sx_L signals pulse.
If any pulses, check for the corresponding Sx volatges.
Trigger SMC_ONOFF_L signal for tests...
 
J

jadao

Member
Tried smc bypass and nothing happens, it continues pulsing.
PM_SLP_S5 is missing 0V
Tried my second U7100 and back to square one with only stable 5,2V at ppdcin_g3h. Wanted to try SMC_Bypass and still nothing happened, I checked at SMC_ONOFF_L and it was low 0,2V.
So I may have an SMC issue... but this doesn't explain to me why with two U7100 replacement, result are not conistent...
also there is no short 0,650 diode mode on SMC_ONOFF_L, R5170 is ok with 10kOhms.
 
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