820-00239 dead. Missing 20v.


Hello again.

I have a 820-00239 that appears dead - no life, no fans.
No USB activity at all.

No signs of any liquid anywhere on either size of the board.
Tried with known good AC adaptor with just the bare board.

I don't seem to get 20v anywhere - the most I get is 5.7 volts.

I'm also fairly unfamiliar with and very confused by the whole USBC 4x ports setup.

With the charger connected to USB TA (JB500 outer USBC port)
PP20V_USBC_TB_VBUS = 5.7V (measured at FB200)
The other ones TA, XA, XB all read 0.0v.

UB400 appears to be getting hot, but nothing else is.

Any advice greatly appreciated.


Hi again 2informaticos.
Thanks for your advice once again, and sorry for the delay.

I measured all 4 LDO rails on all four CD3215 chips.
In diode mode with red to ground, most rails measure between 524 & 570.

However, 2 rails do not, and appear as short circuit.
These are:
PP3V3_UPC_TB_LDO measured at pin 1 of CB408.
PP1V8_UPC_TB_LDOD measured at pin 1 of CB405.


Thanks again for your advice 2informaticos.
Unfortunately, that job went pear shaped. :(

What temperature do you need to remove UB400?
I ended up overheating the board, to the point that other components started floating....its game over unfortunately for this board.

I read that all 4 CD3215 chips have to be working for any to work... is this correct?
Anyway, lessons to be learnt, I guess. :)


Staff member
Always practice on scrap boards, before removing a new BGA type; which you didn't work before.

All CD32xx chips must talk with SMC, before this one decides to switch to 20V.
There can be problems between one, or more chips towards charger side.
But SMC will don't know that, if the charger is connected to a port with good communication all the way; from charger until SMC.