820-00928 short under ub000

[kjchatman]

pp3v3_tbt_t_f is shorted to ground because of a water spill that got under ub000. ppdcin stays at 5v. could this be the issue? i've replaced both cd3215 chips on that side

 

[2informaticos]

PP3v3_TBT_T_F comes from PP3V3_S0.
So you have a short there too.
In fact there are many other components connected.
If your short remains on pin 1 of LB190, then yes, UB000 is shorted.
Does the board start without LB190.
Check if PPDCIN pulses up every 5s at least.

 

[kjchatman]

i've removed ub000 and the short is gone

 

[2informaticos]

"If your short remains on pin 1 of LB190..."
Next time check that.
Or you risk to remove a BGA chip and have same problem after.

 

[kjchatman]

i checked LB190 and everything else before the bga chip was pulled. just wondering if that bga chip is necessary for those cd3215 chips to work

 

[kjchatman]

can this board work without ub000?

 

[2informaticos]

Did you try it?
Do you get PPBUS_G3H at least, without UB000?

 

[kjchatman]

no i can't get ppbus_g3h because the ppcdin is only 5v.

 

[2informaticos]

That is not a reason.
U7000 can generate 13V with 5V on input; didn't think you why are 2 MOSFET pairs on the new boards?
Just need SMC communicates with the external device which only generates 5V as normal.
If SMC cannot talk with the charger, it will also block U7000.
If UB000 is involved in the communication, no way to start the board.

 

[kjchatman]

so i need to put ub000 back to use this board?

 

[2informaticos]

I cannot confirm that 100%.
But I think it needs to be soldered.
Maybe UB300/400 triy to establish a communication with it.

I don't think someone will remove it from an working board, just for test...