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A2485 Not charging. Fan spin. minor liquid damage on charge FETs

S

SolderFungus

Member
I have a A2485 that got a tiny streak of liquid damage on the on the FETs for charging the battery. Q5232 and Q5233. (Picture provided)

Q5233 - CHGR_GATE_Q2 appeared to be shorted to GND. 0.00 in Diode mode.
I cleaned pin 1-4 with some flux and solder and that appeared to relieve the short. D 0.430


Q5232 - PPDCIN_AON_CHGR_R 20V
CHGR_PHASE1 - 11V

I have tried to replace the battery with no luck.
Device will run without usb-c charger connected, but it will not charge. All other functions on the device appears to be working.
Requesting troubleshooting guidance. Thank you.

damage.jpg
 
2informaticos

2informaticos

Administrator
Staff member
How can you write "C5220 and C5260" as short as possible???
We use such notations daily on the forum...
 
2informaticos

2informaticos

Administrator
Staff member
Check all the resistors and traces associated with U5200 and its related MOSFETs.

Post CHGR_BGATE voltage, with charger and battery connected.
 
S

SolderFungus

Member
CHGR_BGATE
Disconnected 3.6V
Connected battery no charger 2V
Battery and charger 2.6V
Started with charger then disconnect charger 3V



Q5232
PPDCIN_AON_CHGR_R D. .620 R 31.4K
CHRG_PHASE1 D .468 R 91mO
CHRG_GATE_Q1 D .700
Values are not settling

Q233
CHGR_GATE_Q1 D .421



R5217 (10K 1%) measures 8.93K Diode reading is .550 (AUX_DET_SHORT)
CHGR_AUX_DET in diode mode is 0.460 while OBDATA says 0.549
Those are the only measurement with a noteworthy deviation around U5200




PPVVBAT_AON 1.170 in diode mode. (OBDATA : 1.630)
Q5270 SAVE_BAD_D Diode 1.170 ( OBDATA 1.625)



Q5240
CHGR_GATE_Q3 Diode 0.0 R 0.01ohm no OBDATA
CHGR_GATE_Q4 Diode Ol R OL no OBDATA
Rest on Q5240 is same as OBDATA at D 0.485/0
 
2informaticos

2informaticos

Administrator
Staff member
CHGR_BGATE with low level enables Q5265 to charge the battery.
It should have the same voltage on pins 1 & 5 (not low); confirm that.

Inspect both ends of battery data cable for corrosion; test with new one.
Be sure to connect it in correct way.
 
S

SolderFungus

Member
Battery cable has been checked in continuity mode and appears to be working.
I dont have a spare cable unfortunately. I also measured voltage and continuity on the PCB side on the battery as well.



Q5265 Battery & Charger connected:
pin 5 11-11.99V
pin 1-3 11.98V
pin 4 CHGR_BGATE 2.6V / 3V or 1.V

Q5265 Battery only:
pin 5 11.V
pin 1-3 11.V
pin 4 CHGR_BGATE 2.6V / 3V or 1.V



however, I got a reading of 11.9V on BGATE now but only sometimes.
I think it will jump to 11V and stay there even if re insert the charger.
When usb-c meter goes to 20v 0a i get 11.98v.

I believe i get 11.98v on BGATE when the device goes to sleep but I cannot confirm 100% that this is the case.
 
2informaticos

2informaticos

Administrator
Staff member
If CHGR_BGATE goes high, battery charging is disabled.
Did you check if battery data cable isn't inserted in reverse direction?
 
S

SolderFungus

Member
1735938765216.png


I'm pretty sure it only connects one way. The "tape tab handles" are facing upwards.
Battery screw is not connected in this image, but it was during testing.
 
2informaticos

2informaticos

Administrator
Staff member
Check diode mode to ground on all SCL/SDA lines around UD102/50.
Also check all agjacent resistors and traces.
Be sure to have good continuity with J5151.
 
S

SolderFungus

Member
1736008058145.png1736008068213.png

Tiny spec of liquid damage spotted around UD102/50 hidden under the CPU tape. I repaired the damaged spot and that restored the charging circuit back to normal.

Many thanks to you, 2informaticos!
 
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