Port is DC Power Jack.AC adapter (Charger) plugs into it. (DC_IN)Example of the DC Power Jack,
http://www.dcpowerjacks.net/catalog/index.php?main_page=product_info&cPath=3_20&products_id=1628Looking at the view all the way to the left, the jack is upside down in relation to how it is actually mounted to the motherboard.All 4 of those prongs go down into the motherboard, and are soldered to the motherboard.The prongs on the sides formed out of the metal case, are for support.The prong all the way to the back goes to the Center Pin, and is the Positive connection.The prong (Pin) in the middle, goes to the inner cylindrical shell within the DC Power Jack, and is the Negative connection.(Along with the two outside prongs used for support)Battery removed use a No.2 pencil, and with the eraser see if you can gently move the Center Pin around.ANY perceptible movement means a bad DC Power Jack, and replacement.If it seems the entire DC Power Jack moves around, it may be damage to the jack, or the solder connections for the prongs to motherboard, are cracked.Cracked solder joints just means use a little rosin flux, and rosin solder to re-solder those solder joints. (Solder connections )DC Power Jack checks OK, normal diagnoses would lead you to the AC adapter. (Charger)Center hole is the Positive ( + ) connection, and where the Positive (Red) probe lead of a multimeter goes.The Negative (Black) probe lead touches the cylindrical outside metal shell of the AC adapter's plug.(Multimeter set to DC Voltage. If just a symbol, the symbol is a dotted line over a solid line.If more than one DC Voltage scale, set the Function knob to the 0 - 50 Volt DC scale.You should read 19 Volts (DC)Have an assistant gently wiggle the cable from AC adapter to laptop, and power cord to AC adapter, as you check DC Voltage.Any fluctuation in the reading means the cable, or power cord has broken wires.
http://www.amazon.com/G51jx-a1-G51jx-x1-G51vx-rx05-G60jx-rbbx05-G60vx-rbbx05/dp/B004CF4SEIHowever due to your statements I'm willing to bet the problem is/are Power MOSFETS on the motherboard, and/or ceramic capacitors.(Multi-Layer Ceramic Capacitors, and Surface Mount Device.MLCC and SMD ceramic capacitors)Information on the above using HP Pavilion dv6000 series, and Pavilion dv9000 series Notebook PC's, as an example,
http://mayohardware.blogspot.com/2010/04/important-parts-on-dv6000-and-dv9000.htmlAlso go to the second photo down, that has the Alpha and Omega Semiconductor - AO4407 - Power MOSFET, circled in Yellow.Below it, and to the right, are Ceramic Capacitors.There is one above the one on the right, one above it, and one to the right of the top one.Small rectangular shaped objects, with a dark wide band on the middle.If visual signs of blackening, burning, or blistering, are shown on any of the Power MOSFETs, or ceramic capacitors, they need to be replaced.Showing average cost of a Power MOSFET used a LOT in laptops, for this power application;Fairchild Semiconductor International - FDS6679 - Power MOSFET,
http://www.mouser.com/Search/Refine.aspx?Keyword=FDS6679$1.01 USDMLCC ceramic capacitors used, are about 62 cents to 80 cents each.Now price a replacement motherboard.However, logic does sometimes dictate just replace the motherboard.Why?Because depending on electronic components that have failed, the damage could be further.Or components may be weakened, and won't take long to fail after replacing failed ones.Can you disassemble the laptop, and un-solder/solder the needed electronic components?If so, and the repair fails down the road, just open it back up, and decide if a motherboard is logical.(Price/availability)IMHO (It's in my 'AOE', so that is what I would do)1)
http://www.youtube.com/watch?v=3NN7UGWYmBY2)
http://www.youtube.com/watch?v=5uiroWBkdFY3)
http://www.youtube.com/watch?v=f_yFDpSTfao4)
http://www.youtube.com/watch?v=MqivHi7QjvkFor additional questions please post in a Comment.Regards,joecoolvette