820-02098 keeps burning resister.

[Jaybloe]

Hi, I've encountered multiple problems.
usb-c meter is measuring 5.14v 0.00a

PPBUS_AON is 0v and has a 0.66a short to ground when supplied with 1v, it also has a diode reading of .020 with a ohm reading of 14ohms. I'm not in possession of a thermal camera but alcohol reveals nothing.

the next problem (probably related) is that after i replaced ISL9240 with a corresponding resister R5262 (that was reading 0.5 ohms) another resister keeps blowing R5222 into the Kohm range.
this happens even when ISL9240 is not on the board.

CHGR_AUX_DET: 1.285v
CHGR_CSI_P: 5.158v
CHGR_CSI_FILT_P: 5.158v
CHGR_CSI_N: 5.158v
CHRG_CSI_FILT_N: 5.158v

Both CHRG_CSO's are 0V
CHGR_BOOT 1&2 are created 3.3v

PP1v8_S2: 0v
There is no liquid damage on the board
What should be the next thing i need to check?

 

[2informaticos]

First of all, welcome to the forum!

"even when ISL9240 is not on the board"
For the future, NEVER let MOSFETs from a buck converter with the Gate floating on air!!!
Q5230 may be burnt now; just in case, check Q5240 too.

"resister R5262 (that was reading 0.5 ohms) another resister keeps blowing"
Did you check C5262???

"R5222 into the Kohm range"
To the ground, or between its pins?

"PPBUS_AON... has a diode reading of .020 with a ohm reading of 14ohms"
Remove F5200/1 and check which side the bad reading remains.

 

[Jaybloe]

Thank you!, my apologies for responding so late.

"For the future, NEVER let MOSFETs from a buck converter with the Gate floating on air!!!"
I will not do that again..

"Q5230 may be burnt now; just in case, check Q5240 too"
diode mode measures:
gnd-phase1&2: 0.534
CHGR_GATE_Q1-4 have no value
(isl9240 is not soldered on atm)
I will solder it on tomorrow and measure again

"Did you check C5262???"
Yes it measured as is supposed too, already replaced it to be sure.

To the ground, or between its pins?
Between its pins


"Remove F5200/1 and check which side the bad reading remains."
after removing the fuses the short is on the PPBUS_AON side.

 

[2informaticos]

"Between its pins"
Replace R5222, is also burnt; it should be 1 ohm resistor.

"the short is on the PPBUS_AON side"
Check if any big coil gets same 14 ohm to ground.

 

[Jaybloe]

The closed i measured to 14 ohms was on LC260&LT000 18.6ohms to ground
Whilst inspecting the coils i found out LT000 is almost crumbling apart 100kohm across the pins.

@LC260 PPB5v_S2_MAIN&P%VS@TPS_PHASE measure 0.027 in diode mode.
@LT000 PP5V_KBDBKLT_ISNS measures 0.579, KBDBKLT_SW2 measures 0.027

 

[2informaticos]

Is better to use ohm scale to compare low value resistances.

Seems to have problems with 5V_S2 power rail.
Remove UC260 and check diode mode to ground at PPBUS_AON and 5V_S2_MAIN.

 

[Jaybloe]

With UC260 removed:
PPBUS_AON: 15.2ohms, 0.027 in diode
5V_S2_MAIN: 19ohms, 0.022 in diode
All to ground

 

[Jaybloe]

I found part of the problem!
I removed U5700.
PP5v_S2_MAIN: into Kohm, 0.395 in diode mode
PPBUS_AON: into Mohm, 0.480 in diode mode
Perhaps u5700 went bad after ISL9240?

 

[2informaticos]

Looks like; change it.