820-00281 - Intermittent doors

[Palhano]

The logic board arrived dead. There was a short circuit in the PP3V3_S4_SOC_PMU line (C4203).

After the repair, it turned on and worked fine for 1 day. Then it stopped charging the battery, all ports with the battery are 20v. Without the battery, 5v and 0.004a. The ports of the U3200 and U3100, the tester keeps restarting. All LDO lines are OK.

While I was analyzing it, it started working normally again, the board only turned on with the charger and the battery charging. But after a few hours of testing, it stopped again.

I replaced the U3200 and U3100, but the problem persists.

Any tips?

 

[2informaticos]

The problem may be on the other side.
Cycling ports can mean board tries to boot.

 

[Palhano]

I think the problem was the UB400, in the measurements it didn't have the 1.1v LDO (with the charger in its port). I changed it and it started working again. I'll test it and see if it doesn't stop.