If you have a broken Dell laptop charger, you might be tempted to simply cut the wire, strip the ends, and splice it back together or attach a new tip. However, looking inside a Dell charger cable reveals not two wires (positive and negative), but . This often leads to confusion and, if wired incorrectly, a fried laptop motherboard.
This is a thin center wire. It connects to a small 1-Wire EEPROM chip inside the charger brick. This chip tells the laptop: "I am a genuine 65W (or 90W/130W) Dell charger." Internal Wiring Diagram (DC Jack Side) 3 Wire Dell Laptop Charger Wire Diagram