Gigabyte P34G Laptop does not turn on when plugged in

Hi All,

my P34G laptop has recently had a problem where laptop does not turn on when it's plugged into power supply and battery is disconnected.
it does however turns on with battery.
my initial assumption was that power supply is unable to provide power to the motherboard. so I check the adaptor head. it is supplying 19V.
then I checked the power jack, there are 3 pins at the back attaching the power jack to motherboard, there is 19V reading between the outer 2 pins.
since laptop operates on battery just fine, my guess is motherboard is not the issue.
could it be that power jack is faulty even though I get 19V readings on it? or is this an issue of the circuitry between power jack and rest of the motherboard?
is it worth purchasing a power jack and replacing it?

what do you think?