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820-00840-a Wont start missing PP5V_S5

C

CRC2018

Member
so i've received a liquid damaged 820-00840-a in today. Liquid damage was focussed around the U7650 area. I've cleaned it all and visibly inspected the area - resoldered U7650 as pins 31 and 26 were not shiny anymore.
If I connect charger it negotiates to 20v as expected but with a tiny spike to 0.07a current draw then drops to 0.00a. PPBUS is present at 13V but there is no PP5V_S5. PP5V_S5 is not shorted to ground either. I'm wondering if this is a dead U7650 or if water damage at U7650 might've killed U7800.

U7800 area is clean
 
2informaticos

2informaticos

Administrator
Staff member
First check diode mode to ground at 5V_S5.

Post basic voltages for U7650; pins 23, 12, 13, 22, 29, 21, 4.
 
C

CRC2018

Member
diode mode reading is 0.455 to ground on pp5v_s5
pin 23 -13.06v
pin 12 - 0v
pin 13 - 0v
pin 22 - 3.3v
pin 29 - 0v
pin 21 - 0v
pin 4 - 0v
 
2informaticos

2informaticos

Administrator
Staff member
Check if SMC_PM_G2_EN goes high.
If not, you may need to reball/replace SMC.
Also check signals and voltages at U5000 (SYM 2 OF 2) at page 39.
 
C

CRC2018

Member
SMC_PM_G2_EN is high 3.4V
BUF_SMC_RESET_L is high 3.4v
PP1V2_S5_SMC_VDD - 1.2v
PP3V3_S5_SMC_VDD - 3.4v

also of note but probably not important right now L6600 and L6601 are missing. They appear to be just for audio so i'm not too concerned about them right now!
 
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