820-01958 stuck at 5V

[drmacbookth]

I have an 820-01958, no obvious liquid damage that is stuck at 5V and 0.25A. After 10 seconds meter goes black and reboots to 5V. PPBUS is 12.31V, I have 3.3, 1.8 and 1.1v. None of the CD3217 is getting hot or looks bad. Should I try replace or something else to try first?

 

[2informaticos]

If USB meter restart, means the board try to start and probably SMC detects a fault and restart power on sequence.
Check for short on all secondary power supplies.

If you connect the battery, USB ports switch to 20V?

Just in case, try DFU revive.

 

[drmacbookth]

Tried DFU already didnt work, battery is the same 5V. Will check for shorts more thoroughly.

 

[drmacbookth]

So no shorts on all powerlines. I have the 3.3, 1.1 and 0.82v voltages. Looks like CPU is not turning on. When i check U7100 power in, I get 12.3v on VIN and 0V on VCC 5V. Should 5V be present here prior to boot, I assume yes? No short on these lines though. U7650 gives 3.3v no 5V. Do these boards work in the same way as the old ones and I need EN and SLP signals from CPU?

 

[2informaticos]

PCH/CPU not involved yet, until G3S and SSD voltages appear.
820-01598 power on sequence available, should serve for 820-01958 too.

Do you note any pulse at P5VG3S_EN?

Any fault history available?

 

[drmacbookth]

no fault history and board looks new. I dont get any pulse on EN

 

[2informaticos]

T2 and U7800 are the suspects here.