820-00281-a 5v loop

yair37

Member
hi, i have 820-00281-a dead, water damage at u3200 area (u3200 replaced) and at area u3100(replaced too) i was also replace u7000 and u6903..now its give me 5v loop at charger i was look for short on ppbus_3gh(0.9v) but cant find any....any idea?
thanks!
 

2informaticos

Administrator
Staff member
Do you get 3V3_G3H?
Also check SMC_RESET_L and BUF_SMC_RESET_L.

Inspect the other two USB-C ports; all four CD3215 chips must talk with SMC.
Check if all LDO voltages come out from these chips.
Also compare diode mode readings on all of their power rails.
 

yair37

Member
3V3_G3H - 3.4V
SMC_RESET_L- 3.4V
BUF_SMC_RESET_L. -3.3V

At all 4 its the same (5v - 5s loop)
alll the LDO voltage are O.K except PP1V1_UPC_TB_LDO_BMC from UB400 AND ub300.
 

2informaticos

Administrator
Staff member
You must get all LDO voltages.
Be aware, you must connect the charger on the corresponding port.

Compare diode mode readings on LDO lines, between the 4 CD3215 chips.
 

yair37

Member
U3200
PP3V3_UPC_XB_LDO - 3.4v dido mode----505
PP1V8_UPC_XB_LDOA - 1.8v ---480
PP1V8_UPC_XB_LDOD - 1.8v---480
PP1V1_UPC_XB_LDO_BMC - 1.0v---505

U3100
PP3V3_UPC_XA_LDO -3.3v ---505
PP1V8_UPC_XA_LDOA -1.8v----1270
PP1V1_UPC_XA_LDO_BMC -0v----1
PP1V8_UPC_XA_LDOD -1.8v---480

UB300
PP3V3_UPC_TA_LDO - 3.4v----506
PP1V8_UPC_TA_LDOA -1.8V----1303
PP1V8_UPC_TA_LDOD -1.8V----480
PP1V1_UPC_TA_LDO_BMC-1.0V---1750

UB400
PP3V3_UPC_TB_LDO -3.4V----503
PP1V8_UPC_TB_LDOA -0V----514
PP1V8_UPC_TB_LDOD -1.8V----480
PP1V1_UPC_TB_LDO_BMC - 0V----730
 
Last edited:

yair37

Member
some update..i was replaced U3100 AND UB400, at the u3100/3200 still 5v loop, at the UB400/300 one still 5v loop and one 5v stable....
 
Last edited:

2informaticos

Administrator
Staff member
You still have problems on USB-C areas.
A common problem (after these areas), will cause the same behaviour on all ports.
 

yair37

Member
update, i was just got 4 new ones...i was replaced all 4, at the u3100/3200 still 5v stable, at the UB400/300 still 5v loop...so its from other place, i think..what can i check next?
 

2informaticos

Administrator
Staff member
You cannot have different behaviour from an issue on a common point.
USB-C areas have more chips, not only CD3215.
Check for corrosion on the corresponding ROMs and Thunderbolt chips.
 

yair37

Member
there was corrosion near u4200 and some V are missing like P3V3_S4_SOC_PMU, i was put some flux and move it..but the same, reball/ replace?
this cup are missing c4916 pp3v0_messa, importent for this problem?
 
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