Laptop DC Power Input Stage: Shorted input capacitor | Auckland
Pattern to record: The adapter protection trips immediately when connected to the computer.
Identify the input design
This guide concerns a laptop powered through a round DC jack. The adapter label and the laptop model determine the required voltage, polarity and rating; a plug that fits is insufficient evidence of compatibility. One possible explanation is that a damaged filtering capacitor pulls the main input rail toward ground.
Stop before further damage
Stop using any connector that sparks, smells hot or has visibly melted plastic. Repeatedly reconnecting the adapter can worsen board damage.
Workshop checks
- Compare adapter voltage at rest and under load, inspect the connector mechanically and trace protected input power with the battery isolated.
- Measure rail resistance with power removed and isolate the shorted section methodically.
Repair and power verification
If the checks support this cause, replace the confirmed failed capacitor and inspect nearby components for heat stress. Verification should cover cold start, charging under load, connector temperature, battery transition and repeated plug cycles.
For an assessment of your barrel-charger laptop, contact AEPC in Burswood or call 027 908 8880. Provide the model and the conditions that reproduce this problem. Workshop visits are by appointment.