We would like to share some ideas for resolving issues in Acer One z1402 where battery cannot be detected by the system. The troubleshooting concept here may be applicable to other laptops with similar charging circuit designs.
SYMPTOMS:
- Battery is not detected in Windows
- Charging indicator does not lit
REPAIR NOTES:
- BAT+ is normal and BAT_SMBCLK and BAT_SMBDAT have pullup voltage of 3.3V. Also, no activity were noted in the oscilloscope.
- Found an abnormal voltage reading in battery detector circuit, BAT_V = 0V
- Pin 3 of Q58 is 0v which means BAT_V is forced to 0v. Expected voltage at this pin should 2.375V for normal operation. (see image)
- Pin 2 has 3.3V which should forces pin 6 and pin 5 to 0V. (see image)
- But actual voltage at pin 5 is 5v which makes it abnormal
- Further test indicates that D1-S1 junction is open which results in inconsistent reading of 5v in pin 5 and 0v in pin 3.
- Replacement of Q58 fixed the problem
Resolving cases like this can be easily fixed if every component will be checked for normal operation using datasheet or schematic diagram. However, analyzing the circuit and what voltage to expect as you test each pin of the IC is a difficult challenge.
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