820-00840 No PP3V3_G3H

[cwalex]

Hi,

I have dead 820-00840. It had liquid damage around U2890 which I cleaned up and ran jumper wires etc. 5V on the USB C power meter.

I have:
PP3V3_G3H = 0.17V
PM_EN_P3V3_G3H_R = 0V

Neither are short to gnd. Any help from here would be appreciated.

 

[JohnB8812]

Is PPDCIN 5 volts? If so, replace U7000 as it produces the enable for U6903.

 

[cwalex]

R7020 is 0V. Resistors are OK and have continuity to U2890.

 

[cwalex]

PP20V_USBC_XA_VBUS=5V but PPDCIN_G3H=0V. Don't I need this rail before U7000 is suspect? The power system on these boards makes my brain hurt.

 

[JohnB8812]

If you don?t even have PPDCIN check for a short on that line. Also for sure known good 87 watt USBC brick and cable? Also ports aren?t badly corroded?

 

[2informaticos]

Check all LDO lines.
And compare voltages too.

 

[cwalex]

Good board (diode mode):
PP1V8_UPC_XA_LDOD=0.483V
PP3V3_UPC_XA_LDO=0.515V
PP1V8_UPC_XA_LDOA=0.525V
PP1V1_UPC_XA_LDO_BMC=0.520V
PP1V8_UPC_XB_LDOD=0.484V
PP3V3_UPC_XB_LDO=0.515V
PP1V8_UPC_XB_LDOA=0.525V
PP1V1_UPC_XB_LDO_BMC=0.520V

Faulty board (diode mode):
PP1V8_UPC_XA_LDOD=0V!
PP3V3_UPC_XA_LDO=0.483V
PP1V8_UPC_XA_LDOA=0.526V
PP1V1_UPC_XA_LDO_BMC=0V!
PP1V8_UPC_XB_LDOD=0.494V
PP3V3_UPC_XB_LDO=0.495V
PP1V8_UPC_XB_LDOA=0.535V
PP1V1_UPC_XB_LDO_BMC=0V!

Faulty board (Voltages):
PP1V8_UPC_XA_LDOD=0V
PP3V3_UPC_XA_LDO=0.094V
PP1V8_UPC_XA_LDOA=0V
PP1V1_UPC_XA_LDO_BMC=0V
PP1V8_UPC_XB_LDOD=0V
PP3V3_UPC_XB_LDO=1.547V
PP1V8_UPC_XB_LDOA=0V
PP1V1_UPC_XB_LDO_BMC=0V

I guess that's why I don't have PPDCIN_G3H.

 

[cwalex]

You're right of course It was U3100. Now I gotta do some reballing. Thanks a lot for the help.

 

[cwalex]

Replaced U3100, I now have PPDCIN_G3H=5V. PP3V3_G3H is ~2.9V. When I plug the USB C power meter in to the port connected to U3100 I get 5V and ~400mA but on the port connected to U3200 I get 5V ~170mA. Does that sound like U3200 is bad as well or that I goofed soldering U3100?

 

[cwalex]

Readings after replacing U3100

Faulty board (diode mode):
PP1V8_UPC_XA_LDOD=0.492V
PP3V3_UPC_XA_LDO=0.506V
PP1V8_UPC_XA_LDOA=0.534V
PP1V1_UPC_XA_LDO_BMC=0.530V
PP1V8_UPC_XB_LDOD=0.494V
PP3V3_UPC_XB_LDO=0.495V
PP1V8_UPC_XB_LDOA=0.535V
PP1V1_UPC_XB_LDO_BMC=0.529V

Faulty board (Voltages):
PP1V8_UPC_XA_LDOD=1.817V
PP3V3_UPC_XA_LDO=3.325V
PP1V8_UPC_XA_LDOA=1.793V
PP1V1_UPC_XA_LDO_BMC=0V
PP1V8_UPC_XB_LDOD=1.375V
PP3V3_UPC_XB_LDO=2.32V
PP1V8_UPC_XB_LDOA=0V
PP1V1_UPC_XB_LDO_BMC=0V

 

[2informaticos]

When you check B port voltages, plug the charger on the corresponding USB-C port.
And compare again with good board.

PP3V3_G3H is low on both cases?
Check it on R6999.

 

[cwalex]

Plugged into corresponding ports.
PP1V8_UPC_XA_LDOD=1.8V
PP3V3_UPC_XA_LDO=3.3V
PP1V8_UPC_XA_LDOA=1.8V
PP1V1_UPC_XA_LDO_BMC=0V
PP1V8_UPC_XB_LDOD=0.5V
PP3V3_UPC_XB_LDO=1.5V
PP1V8_UPC_XB_LDOA=0V
PP1V1_UPC_XB_LDO_BMC=0V

PP3V3_G3H=0.1V when plugged into port corresponding to B and 2.9V when plugged into A.

Comparing the diode mode readings to the good board they are all very close.

 

[cwalex]

Here are the readings anyway.

Good board (diode mode):
PP1V8_UPC_XA_LDOD=0.483V
PP3V3_UPC_XA_LDO=0.515V
PP1V8_UPC_XA_LDOA=0.525V
PP1V1_UPC_XA_LDO_BMC=0.520V
PP1V8_UPC_XB_LDOD=0.484V
PP3V3_UPC_XB_LDO=0.515V
PP1V8_UPC_XB_LDOA=0.525V
PP1V1_UPC_XB_LDO_BMC=0.520V


Faulty board (diode mode):
PP1V8_UPC_XA_LDOD=0.492V
PP3V3_UPC_XA_LDO=0.506V
PP1V8_UPC_XA_LDOA=0.534V
PP1V1_UPC_XA_LDO_BMC=0.530V
PP1V8_UPC_XB_LDOD=0.494V
PP3V3_UPC_XB_LDO=0.495V
PP1V8_UPC_XB_LDOA=0.535V
PP1V1_UPC_XB_LDO_BMC=0.529V

 

[2informaticos]

If diode mode readings are correct, voltage values point to internal problem of U3200...

 

[cwalex]

I'll replace U3200.

 

[cwalex]

Replaced U3200, powers on and boots macos

Thanks very much for your help.