The DC Power Jack on the laptop is also known as an AC DC (direct current) power port, dc power input, dc power connector, dc power socket, pin, inlet, prong, point, inlet, receptacle part, basically it is an inside piece in the laptop where the dc power plug (tip part of your AC adapter cable) plugs into. The first signs that it’s starting to fail is if for quite some time you had to wiggle the plug around to make the system power up or charge the battery,