820-00928 Not booting 20v / 0.04A

No liquid damage, board in perfect condition. According to customer, this MacBook suddenly died on him.

Measurements:
PM_PWRBTN_L
3,3​
PPBUS_G3H
12,6​
PM_RSMRST_L
3,3​
PPBUS_HS_CPU
12,6​
PM_DSW_PWRGD
3,4​
PPBUS_HS_GPU
12,6​
RTC_RESET_L
3,1​
PPBUS_HS_OTH5V
12,6​
PCH_SRTCRST_L
3,1​
PPBUS_HS_OTH3V3
12,6​
PCH_INTRUDER_L
2,8​
PPBUS_S4_HS_TPAD
12,6​
S5_PWRGD
3,3​
PP3V3_G3H
3,4​
PM_SYSRST_L
3,3​
PP3V0_G3H
3,1​
PM_PCH_SYS_PWOK
0​
PP1V8_SUS
1,8​
PM_PCH_PWROK
0​
PP1V8_S4
0​
PLT_RST_L
0​
PP1V0_SUS
1​
SMC_RESET_L
3,4​
PP1V0_S3
0​
PP3V3_S5_T139
3,3​
PM_SLP_S5_L
0​
PP3V3_S4_SOC_PMU
0​
PP5V_S5
5​
PP5V_S4
0​
PP3V3_S5
3,3​
PP3V3_SUS
3,3​
PP3V3_S4
0​
PP3V3_S4_T151
0​
PP3V3_S4SW_SNS
0​
 

2informaticos

Administrator
Staff member
Did you test the board alone on the desk?

Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L.

BTW, do you really need to measure PPBUS in 6 points???
 
In order of appearance:
  • Yes, tested board alone
  • PM_PWRBTN_L drops to .36V after triggering SMC_ONOFF_L
  • Probably not, took the path of least resistance as I wasn't sure there were any 0 ohm resistors or 'switches' between these lines. I'm sure only having 5 of these 6 would cause some kind of trouble.
 

2informaticos

Administrator
Staff member
"PM_PWRBTN_L drops to .36V after triggering SMC_ONOFF_L"
Check for pulse at PM_SLP_S4_L at same time.

BTW, PM_PWRBTN_L should go back to 3V, once SMC_ONOFF_L is released.
 
Last edited:
Top