PlzBro 820-00840 5v cycling no 20v

820-00840
Liquid Damage
Liquid was around and down both USB C charging Circuits and controllers
Cleaned area and found 5 burnt traces
Burnt traces
R3351 Burnt PPBUS_G3H pad - Ran jumper to R3451 PPBUS_G3H side and replaced R3351 with new 10K resistor
R3360 Burn via - Cleaned and checked continuity to resistor and output and has continuity
PIN 46/55 of U3100 (TP_NC_UDP_XA_SWD_CLK) Test point burnt off board but BRD shows this goes no where. When Charger plugged in these lines are both 3.3v
PIN 55 of U3200 (TSP_USP_XB_SWD_CLK) Test point burnt off board. Line reads 3.3v when charger is plugged in

PP3v3_G3H is 3.368v
PPBUS_G3H is 5v and cycles 0-5v every few seconds as if there is some type of reset.

U3100 and U3200 were clean when pulled and no burnt pads under the chip or corrosion. Reballed and reinstalled and no change.
I am ordering new ICs but was wondering if Im missing something else since the chips had no signs of liquid under them.
 
Last edited:

2informaticos

Administrator
Staff member
U3100/200 have firmware; no way to put new ones.
Must pick them from donor board; not identical model, but chips code termination should be the same (i.e A03, C01).

"PPBUS_G3H is 5v and cycles 0-5v every few seconds"
For sure, isn't PPDCIN_G3H?
However, check for short between PPBUS_G3H and PPDCIN_G3H.
 
No short between PPBUS_G3H and PPDCIN_G3H
PPDCIN_G3H with charger plugged in is 5.12v constant
Now PPBUS_G3H is 0v and voltage on the Coils USBC_X_CC1, etc are bouncing around 1-2v
 

2informaticos

Administrator
Staff member
You got too much corrosion on USB-C controllers area.
There could be some traces inside board affected too.

Check for short D-S all 4 MOSFETs from Q7030/40.
Also check voltage and diode mode for all LDO from U3100/200.
 

JohnB8812

New member
If you for sure have no corrosion near the CPU fets, this sounds to me like bad CD3215s especially if PP3v3_G3H is present. Do a diode mode of all the LDO lines near both chips 3v3 1v8 etc and compare
 
I'm at home right now but before I left I checked 3v3out 1v1 ldo 1v8 ldo and some other power rails around those chips

1v1 was 1.08-1.1v
1v8 was 1.79v
3v3 out was 3.29v
??????there was one other 3v3 line that was also 3.29v
the ldo voltages I believe were only present on 1 chip at a time dependent on which USB C port was plugged. Which makes sense.
I guess what I'm failing to understand here is what OKs the switch from 5v to 20v. Is this all inside the two TI ICs?
???
 
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