Check the output of the AC adapter (Charger), or skip to check the DC Power Jack, first.
A) DC Power Jack:
The jack on the laptop that the AC adapter (Charger) plugs into.
IF, this is in reference to an HP Pavilion dv2000z series of Notebook PC, this is what the jack looks like not installed,http://www.dcpowerjacks.net/catalog/index.php?main_page=product_info&products_id=1051
In the views of the jack, the pins and blade are on the Bottom of the jack.
They go down through the motherboard, and are soldered in place.http://www.aaroncake.net/electronics/solder.htm
Scroll down to Step 5, and observe the Solder Joints.
IF, a solder joint, (Or more than one), is cracked, the DC Power jack will Not flow power to the laptop.
ALL power removed (AC adapter and Battery) see if you can gently wiggle the Center Pin, of the DC Power Jack. Using a non-metallic object is preferred.
See if the entire jack seems to move around.
ANY perceptible movement means a bad DC Power Jack, or solder joint/s.
Laptop is to be completely disassembled, down to the BARE motherboard in your hand. (No Processor, no Ram Memory, Nada )
This is a basic guide to DC Power Jack replacement,http://www.laptoprepair101.com/laptop/2007/12/06/dc-power-jack-repair-guide/
A) You can use a 25 Watt soldering iron, with a No.2 chisel tip.
Keep a damp sponge handy, if you do not have one in a soldering iron stand. Keep the tip CLEAN, and well tinned, at all times.
B) Use Desoldering Braid. (Solder Wick)
Works MUCH better than a Desoldering Tool. (Solder S-ucker Tool)
Unroll a small length. Flatten out a small length, around 2 inches long.
Lay enough of the tip of the Desoldering Braid, across the solder joint to cover it. Then lay the tip of the soldering iron on top of the braid.
Once the braid, AND solder heat up enough, the fine twisted wires of the Desoldering Braid will pick up some solder.
If you overheat the solder joint, the copper circuit trace area under it, can lift right off of the motherboard. Bad times are ahead.
If you overheat the solder joint, the copper circuit trace area under the solder joint, can lose it's tinning, and CANNOT be re-tinned again.
Bad times ahead.
As soon as the solder starts to melt, and you see the braid has picked up some, remove the solder iron, and braid.
Allow the motherboard circuit trace area to cool down.
Then begin again with a fresh new piece of Desoldering Braid.
Cut the solder soaked section off.
Keep going back, until you have removed all of the excess solder that you can.
(Make take a few times, or more, to perform this, and allow the circuit trace area to cool down in-between )
There will be a skin coat of solder left behind. As you heat one of the pins, or the blade, pull up on the jack.
The pin, or blade, will partially come out. It will not come all the way out because of the other pins, or blade, is still soldered in.
Go to the next pin/blade, and heat it up. Pull. The pins, and blade will come out of the motherboard a little further.
Allow the circuit trace area to cool down in-between heating each pin, or the blade.
Keep going around until the jack is free.
You might have a skin coat going across the circuit trace hole.
That's OK, leave it.
When the new jack is installed, the pins, or blade goes against this skin coat. When the soldering iron touches the skin, the pins, or blade, will poke through.
Make GOOD, shiny bright solder joints. A dull, cold solder joint, will have you scratching your head.
B) If the DC Power Jack proves to be good, with the simple test of the device to see if it will wiggle, go to the AC adapter. (Charger)
The Center Hole in the plug that plugs into the DC Power Jack, is Positive. The outer cylindrical metal shell is Negative.
Positive (Red) probe lead to Center Hole, Negative (Black) probe lead to outside cylindrical metal shell.
Function knob set to DC Voltage. (If just a symbol, the symbol is a dotted line over a solid line. If more than one scale, set it to the 0 - 50 Volt scale )
You should be reading VERY close to 18.5 Volts.
Also have an assistant wiggle the Power Cord, and the cable from the adapter unit, TO the laptop.
An intermittent reading indicates a broken wire.
DC Power Jack, and AC adapter check out, the problem is the power controller chipset.
Chip and Chipset are slang terms for I.C.
The power controller chipset is a power MOSFET.
Here are two examples used in a Lot of laptops,
When bad, generally the power controller chipset will burn up, and blacken.
Note that in both examples above, that the chipsets are in a D2PAK surface mount design.
The J leads are easy to unsolder, and solder.