820-00239 No 20V

brunomotter

Member
Hello. Got this board here that has bee cleaned by another store because of liquid damage, so I don't really know where original damage was. After some inspection I found a blown coil, L4004 was gone and so was its pin 1 trace, so I rebuilt it with a wire, there's no shorts I could find. As U3200 area looked a bit bad I decided to replace U3200 as board was not negotiating 20V with charger. I inspected all components around it and everything is measuring good. Before replacing it I was getting 5V, 50mA on all ports except the one corresponding to U3200. After replacement I now get 5V 50mA on all ports. I'm missing PP1V1_UPC_XB_LDO_BMC but there are no shorts to GND on it. I'm stuck now. I'm having serious trouble to understand this messy USB-C architecture... I compared BMC diode readings from all ports and all of them give from 0.458 to 0.475, very similar readings, so I think probably all CD3215s are ok.
 
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2informaticos

Administrator
Staff member
1V1 LDO must appear only on the powered USB port.
Is it present on the other 3 ports, missing only at u3200?

Compare diode mode readings of all LDO rails between the 4 CD3215 chips.
Do you get PP3V3_G3H?
Any voltage at F7000?
 

brunomotter

Member
All ports are missing that signal. Yes, PP3V3_G3H is present. Here we go:

U3200:

PP3V3_UPC_XB_LDO - 0.474
PP1V8_UPC_XB_LDOA - 0.495
PP1V8_UPC_XB_LDOD - 0.461
PP1V1_UPC_XB_LDO_BMC - 0.477

U3100:

PP3V3_UPC_XA_LDO - 0.167
PP1V8_UPC_XA_LDOA - 0.496
PP1V8_UPC_XA_LDOD - 0.462
PP1V1_UPC_XA_LDO_BMC - 0.477

UB300:

PP3V3_UPC_TA_LDO - 0.472
PP1V8_UPC_TA_LDOA - 0.477
PP1V8_UPC_TA_LDOD - 0.446
PP1V1_UPC_TA_LDO_BMC - 0.461

UB400:

PP3V3_UPC_TB_LDO - 0.471
PP1V8_UPC_TB_LDOA - 0.476
PP1V8_UPC_TB_LDOD - 0.445
PP1V1_UPC_TB_LDO_BMC - 0.458

Looks like U3100 is dead. Will replace it and post back.
 

2informaticos

Administrator
Staff member
Did you check 1V1 LDO on each chip connecting charger to corresponding port?
Check U2890 and UB090 for corrosion; be sure all traces and surrounding components are good.

BUF_SMC_RESET_L goes high?
 

brunomotter

Member
1V1 LDO appears on the UB300 and UB400 side(both ports) but not on the other 2 ports. No corrosion and no missing/looking bad components around U2890 or UB090. BUF_SMC_RESET_L is 3.3V on all ports.
 

2informaticos

Administrator
Staff member
Then you still have a problem on U3100/200 area.
Compare diode mode readings to ground on several points of both left/right USB-C areas.
Check the value of all resistors from pages 28-30.
 

brunomotter

Member
I decided to check the value of all resistors around U3100 and U3200 and found that R3205, R3203, R3209 and R3208 were all reading weird. So I replaced all of them. Now I have correct readings but still stuck on 5V and no LDO_BMC being generated on U3100/200 ports. Now, suddenly UB300/400 ports decided to keep resetting in loop. I'm almost throwing this board on the other side of the street.
 
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2informaticos

Administrator
Staff member
Power cycling could be sign that board tries to start on UB300/400 side.
Possibly short, or overcurrent detected on secondary supplies...
 

2informaticos

Administrator
Staff member
Still problems on USB-C, as you don't have the same behavior on all ports.
But apart of that, there must be a problem with some secondary power rail.
What happens if you connect the battery (with some charge)?
 
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