Acer Aspire 3 A314. Not Charging.

[ronaldopdias]

Laptop Model: Acer Aspire 3 A314
Motherboard Model: DA0Z8EMB8C0 - Model: Z8E
Charging IC: BQ24780 which I have repalced.

Issue Description:
I'm experiencing an issue with the charging system on this laptop. The BQ24780 charging IC is not working as expected. The main problems are:

1. ACDET is missing (0V):, Reading 0V on the ACDET pin.
2. ACOK is not present (0V): Is missing as well.
3. No SMBus signals (SDA and SCL are missing): The SDA and SCL signals for SMBus communication are not present. There is no clock (SCL) or data (SDA) activity on these lines.

What I Have Checked So Far:

• VIN (19V) is present: I have confirmed that the adapter voltage is reaching the BQ24780 IC..
• ACDET Divider Circuit (R1, R2): I checked the resistor divider that creates the ACDET voltage from VIN. The resistors are present, and they appear to have the correct resistance values.
• No Shorts on ACDET: There is no short between the ACDET pin and ground.
• Pull-up Resistors for SDA/SCL: I checked the pull-up resistors for the SDA and SCL lines, but there is no signal activity.
• REGN Pin (6V): The REGN pin on the BQ24780 is not producing 6V.
• Checked for Shorts on SDA/SCL: No short circuits were found on these lines.

Symptoms:

• The laptop does not charge.
• Laptop works fine on Battery.
• The AC adapter is not detected (since ACDET and ACOK are missing).
• No communication between the EC and the BQ24780 via the SMBus (no signals on SDA/SCL).
• Laptop works Jumping a wire between the 1st Mosfet to the second Mosfet, but battery not charging.

I appreciate any advice or guidance you can provide. If you need more details, I can share measurements or photos of the board. Thank you in advance for your support!

[mon2]

As you are noting, fault is in ACDET. The R1 resistor must receive the raw adapter voltage. Confirm this.

Is there a trace from R1 to the adapter raw voltage?

[mon2]

Do post clear pics of the replaced charger IC for a review.

[ronaldopdias]

Yes, it receives 19V from the adapter, but the other side is 0V.

[mon2]

Remove all power. Measure the resistance across the tips of R1 resistor.

Repeat to measure the resistance of R2 resistor. Post each measurement in ohms.

[ronaldopdias]

R1 - side 1 to the IC - 75ohms
- side 2 from adapter - 270ohms

R2 - side 1 - 76ohms
- side 2 to ground - 0ohms

[mon2]

Can you share the full markings of your logic board?

For example, A314-41, etc.

If available, link the schematic but post it inside of the dedicated schematic forum. Need to check the values of these resistors which appears to be quite low.

To confirm on the resistor measurements. With no power to the logic board, meter in resistance mode, place one meter probe on one side of R1. Other meter probe on the other lead on R1. Then repeat to test R2 in the same manner.

Is your meter an auto mode type or manual scale type? Need to confirm if the units of measure are indeed ohms or kohms.

[mon2]

It is vital to confirm that the 'R1' and 'R2' that build up the voltage divider for ACDET have the proper and safe values. If not, the charger IC can be destroyed.

Only if these resistor values are of the proper resistance, proceed to flux and remove the 2N7002 @ PQ9. This mosfet is shunting the ACDET pin voltage to ground and resulting in the no charge condition of your logic board.

Continue to post your progress, either way.

Sharing a partial schematic of a similar board by Acer.

[mcplslg123]

mon2 it seems you missed the important info provided by OP. REGN is missing whereas VCC is present. So clearly the BQ ic is defective.
Another question .Was the original ic BQ24780 or BQ24780S? You need to replace with exact suffix.

[ronaldopdias]

You're a legend.
BQ24780S is the original IC and I was replacing with BQ24780.
I found the exact suffix with S and replaced.
Laptop is fully operational.
Thank you very much.

[mon2]

Thanks. I think the fault was most likely with the soldering of the replacement component. Assumption here is that the replacement part was a known good device.

The BQ24780 and BQ24780S are identical pin-for-pin replacement parts.

https://e2e.ti.com/support/power-man...the-difference