820-01949 no power

[Kyle93]

Arrived with liquid damage in U3100X/u3100T area and U3100R.

Stuck at 5v. Replaced U100X/U3100T and U3100R along with affected resistors and caps. U2800 was shorted and has been replaced as well with a new chip from Mouser. All traces affected by liquid measure good.

When trying to plug into U3100T the amp meter only comes on if inserted one way facing down. If inserted facing up the meter doesn't come on. Same goes for U3100R.

All LDO voltages are present. What should be checked next?

 

[2informaticos]

Compare diode mode readings on CC1/2 lines between all ports.

 

[Kyle93]

All CC1/CC2 lines now 0.725 after replacing J3300CXT/J3300_CWR

Only reaming issue is 5v and U3100_R causing the meter to cycle. All traces/resistors look good around UB260. Also replaced U3100_R with a known good cd3217 but no change.

What else could cause this?

 

[2informaticos]

You sould compare diode mode readings on all USB connector lines.
There may be a bad protection diode.
All ports must have same behavior.

 

[Kyle93]

The only difference in diode mode readings I can find is 0.172 on PP20V_USBC_R_VBUS, the only port that cycles the meter. The remaining PP20V lines are 0.130

Ive already replaced D3100 C3101_R U3100_R and D3305_CWR

 

[2informaticos]

You may have bad solders on that port.
Bad components should give lower values than normal.

 

[Kyle93]

After reballing U3100_R all port behave the same now. 5v 0.25a.

DZ3350 is missing along with its pads. Can this alone prevent 20V??

Have a working board to compare diode mode readings and cant find any ports now that have a different diode mode reading except for PP20V_USBC_R_VBUS still 0.163 vs all other PP20V_USBC only 0.130 which is the correct value.

When this first arrived it had 20v but would not charge the battery. Not sure where to look next at this point.

 

[2informaticos]

Probably some bad trace, or contact, between CD3217 and that connector.

 

[tech-fix]

Did you ever get to the bottom of this?