Acer Aspire VN7-591G-79RH No power, no charging after battery replacement

[Mixeris]

Had this laptop for while, old battery was almost completly dead. Ordered new Green Cell AC54(AC14A8L-3S1P)battery.

After installing new battery:
No turning on from battery
No turning on from power adapter
No indicator leds

Checked voltage on DC jack: 18.6V
Checked voltage on battery terminals: 10.1V

So I removed main board.
Checked for short circuits between : AD+ and ground, DCBATOUT and ground.

Checked voltages:
AD+ :18.6V
DCBATOUT:18.6V

3D3V_AUX_S5: 3.3V
5V_AUX_S5: 5.0V
As I understand these are responsible for powering KBC.

As I see in schematics battery, charger circuit and KBC(NPCE285PA0DX-GP) is connected via I2C. Unfortunately don't have access to ociloscope.
Have no idea how to move forward, but should I suspect KBC?

[Sephir0th]

Re: Acer Aspire VN7-591G-79RH No power, no charging after battery replacement

I'd start with removing the "new" battery to see whether the device can come on. Also CMOS hard reset strongly advised. If already done, please tell so.

Otherwise proceed with PU4501. Remove all power and set multimeter to Ohms mode, range 200. Resistance to GND of pin 3 and pin 13 please.

[Mixeris]

Re: Acer Aspire VN7-591G-79RH No power, no charging after battery replacement

Thank you for reply!

Board with removed battery have same symptoms.
Also removed RTC battery and did hard CMOS reset.

Resistances for PU4501(TPS51225)
Pin3 - GND 6.48kOhm
Pin13 -GND 32.3kOhm

[mon2]

Re: Acer Aspire VN7-591G-79RH No power, no charging after battery replacement

The AUX rails are working so the resistance to ground for each are expected to be ok.

What are the voltage to ground readings of the following?

Pin 6 (ACDET)
Pin 5 (ACOK#)
Pin 16 (REG)

On charger IC pu4403 ?

PWR_3D3V_EN
PWR_5V_EN
3D3V_PWR
5V_PWR

On pu4501.

[Mixeris]

Re: Acer Aspire VN7-591G-79RH No power, no charging after battery replacement

Voltages on PU4403
Pin 6 (ACDET)-2.56V
Pin 5 (ACOK#)-3.28V
Pin 16 (REG)-5.96V

PU4501
PWR_3D3V_EN - 3.24V
PWR_5V_EN - 3.24V
3D3V_PWR - 3.36V
5V_PWR - 5.10V

[mon2]

Re: Acer Aspire VN7-591G-79RH No power, no charging after battery replacement

What are the topside markings on the charger IC @ PU4403 ?

From the pin symbol, ACOK# = active LOW signal.

If this line is LOW, the AC adapter is OK. Your status is high.

[Mixeris]

Re: Acer Aspire VN7-591G-79RH No power, no charging after battery replacement

Checked again Pin 5(ACOK#)@PU4403 - 0.00V (last time measured wrong spot)
Markings on PU4403 are :
BQ737
TI 47i

[mon2]

Re: Acer Aspire VN7-591G-79RH No power, no charging after battery replacement

Ok. Good to know. Schematic has some house marking.

Quick tests for I2C / SMBUS, check the voltage to ground of:

SCL
SDA

lines with the power adapter connected. Each should be a default logic high value since these are open-drain pins and the local pull-up is used for the soft high status.

If not, remove all power -> measure their resistance to ground.

Also, can check in DIODE mode on the meter:

RED meter lead, yes RED to GROUND.
Black meter lead to point to test.

[Mixeris]

Re: Acer Aspire VN7-591G-79RH No power, no charging after battery replacement

BAT_SCL an BAT_SDA lines are 3.3V

Diode test is 0.456V for both lines.

[SMDFlea]

Re: Acer Aspire VN7-591G-79RH No power, no charging after battery replacement

BAT_SCL an BAT_SDA lines are 3.3V

Diode test is 0.456V for both lines.

Find the switch RESET1 SW-TACT-124-GP ,BAT_G

[Mixeris]

Re: Acer Aspire VN7-591G-79RH No power, no charging after battery replacement

Checked the RESET1 switch, it is working.
This laptop has hole in the back to press this switch with needle, so I understand it is NO.