"Burned" DC in power adapter

That's why I always tell people;

1) Install the Battery
2) Connect the AC adapter (Charger)
3) THEN connect the AC adapter to power.

AC adapter disconnected, remove the Battery.
Press the Power On button in, and hold it in for a count of 10 seconds.
(And I mean 10. Count, 1001,..1002,..1003,..1004, etc)
Let go of the Power On button.

Do this procedure 2 more times.
What we are doing here is clearing CMOS Error Codes, resetting BIOS setup back to the factory default settings; and resetting sensor values in the power circuit section of the motherboard.

Now reinstall the Battery. Reinstall the AC adapter. Plug back into power. WAIT 1 minute, turn the laptop on.

Still no?
Suggest we have a problem Houston.

Power MOSFET's in the power circuit section of the motherboard, or may be just a bad Power On switch, now.

The Sony VAIO PCG-7184L is also the VAIO VGN-NW235F

http://www.insidemylaptop.com/replace-lcd-screen-sony-vaio-nw235f-laptop/

http://www.youtube.com/watch?v=F3KQ6_SlJsw

Use an ESD wrist strap, and have it's alligator clip attached to a good ground source. Average cost is around $3 to $6.
One example.

http://www.radioshack.com/product/index.jsp?productId=2103245

I connect to an unpainted surface, of the metal frame of an open, empty desktop computer case.
I feel an Anti-Static Mat is unwarranted.

You can also set a large metal serving tray (Unpainted), on the table you're working on, and connect to it.
Or a large metal knickknack. (Unpainted)

Use a multi-compartment container for the various screws you will remove.
Label each compartment for the area the screw/s come out of.
SOME screws look VERY similar to other screws.
Advise DO NOT mix them up.

Look at the motherboard where the DC Power Jack is mounted.
(The DC Power Jack is where the AC adapter plugs into, on the laptop)
You'll see Power MOSFET's, and MLCC's surrounding them.

[Multi-Layer Ceramic Capacitor. They are also SMD/SMT, as the Power MOSFET's are.
Surface Mount Device/ Surface Mount Technology ]

This is an example using HP Pavilion dv6000 series, and Pavilion dv9000 series, of Notebook PC's,

http://mayohardware.blogspot.com/2010/04/important-parts-on-dv6000-and-dv9000.html

Uses a Fairchild Semiconductor International - FDS6679 - Power MOSFET, and an Alpha & Omega Limited - AO4407 - Power MOSFET.

Looking at the second photo down with the AO4407 circled in Yellow;
Look at the rectangular smaller object to the immediate Right; that has the dark wide band across the middle of it.
This is an MLCC.

There is one above it, one above that one to the Top; one to the right of the top one; and one to the right of it.
See if any of these are burned/blistered also.

Or it might be worse, Clifton,

http://koti.kapsi.fi/jpa/stuff/pix/travelmate_6292/

May be time for motherboard replacement.

http://www.ebay.com/itm/Sony-Vaio-VGN-NW242F-PCG-7184L-A1747083A-3276432-Laptop-Motherboard-Tested-/281040027261?pt=Motherboards&hash=item416f4a7e7d

Not advertising for seller, nor website. Just presenting an example.

For additional questions please post in a Comment.
Regards,
joecoolvette

[More examples of procuring Power MOSFET's, MLCC's, and other related electronic components; plus procedures for de-soldering/soldering SMD/SMT components,

(Use a low wattage soldering iron (25 Watts?), Rosin core solder, rosin flux paste, and flux paste brush; instead of a Soldering Station.

Use Isopropyl Alcohol, and an old toothbrush to clean the motherboard, after removing components, to remove the residue left behind.

CAUTION!!
Isopropyl alcohol (Rubbing alcohol), is EXTREMELY FLAMMABLE.
Use in a WELL ventilated area with NO sparks or flames present )

http://www.mouser.com/Search/Refine.aspx?Keyword=FDS6679

Scroll down.
One dollar, one penny, USD

http://www.mouser.com/Search/Refine.aspx?Keyword=AO4407

AO4407 is phased out. Using one of the cross-reference examples given,

http://www.mouser.com/ProductDetail/Diodes-Inc/DMP3020LSS-13/?qs=%2fha2pyFadujguNNSgppBRqXbOxXLwzGsZm9SWxz1EqWpzoSJOpHpWA%3d%3d

Scroll down.
78 Cents USD.

[ The 'legs' on the sides are J-leads ]

MLCC's that are SMD/SMT, and 4.7uf (MicroFarad) examples shown, at 16 Volts (DC),

http://www.mouser.com/Passive-Components/Capacitors/Ceramic-Capacitors/Multilayer-Ceramic-Capacitors-MLCC-SMD-SMT/_/N-b2cj?P=1z0wrjcZ1z0x565

http://www.youtube.com/watch?v=5uiroWBkdFY

http://www.youtube.com/watch?v=b9FC9fAlfQE

The charger may be bad, will it charge the battery? a common problem is the DC jack in the laptop breaks connection on the motherboard internittent operation or no power and shut down. If you can sub the charger that will tell if the power supply is bad or the problem is in the laptop. If the computer is the issue I recommend a professional because it will require extensive parts removal.

Short version?

1.Remove the AC adapter if plugged in, remove the battery.

2.Wear an ESD wrist s-trap, and have it connected to a good ground. Work on a table, have a container with multiple compartments for the screws, and mark where each screw came from. There are as many as 65 screws, and 8 different sizes.

3.Completely disassemble the laptop, down to the bare motherboard in your hand. Remove the LCD screen assembly. No Processor, Cooling Tube, Heatsink, Ram Memory modules, CD/DVD drive, Harddrive, Wireless Antenna module, Keyboard, Nada!

4.Buy a replacement DC Power Jack.
Here is an example of one,

http://powerjack.us/index.php?main_page=advanced_search_result&search_in_description=1&keyword=Sony+Vaio+PCG-K33

5.Use the correct tools.
If you're a really experienced tech, you can use a 30 to 40 Watt soldering iron. No.2 tip. Have a clean damp sponge nearby, to constantly clean the tip.
Make sure the tip is clean and tinned correctly.

Or use a medium priced soldering station.

I advise using soldering wick, (Desoldering Braid), instead of a Desoldering Tool. Works much better.

5.Use the correct soldering procedures.

Linger too long when heating up the solder joint, to remove the DC Power Jack, and you stand the chance of burning the board. (Motherboard)

Also could lift the Circuit Trace right off of the board.
(Circuit Trace may be thought of as a very thin, copper wire on the motherboard. It isn't, but this explanation will do)

Do any of the two errors above, and you can use the motherboard for a Frisbee.

My method for removing the DC Power Jack, is to pull up on one lead at a time. Use constant pressure with my finger, and thumb. (Don't get 'Godzilla' on it. It can break. Everything has it's limits!)

I heat the solder joint for that one lead, and try to pull it up, a little out of the board. Then I move over to another lead, heat it, and pull up slightly on it. Keep moving from lead to lead, until finally they start pulling out.

After the jack is removed, the area needs to be cleaned. I use 90 percent Isopropyl Alcohol, and Q-tips.

CAUTION!!!!
This is HIGHLY FLAMMABLE! Keep it away from that hot soldering iron, and use in a Well ventilated area.
Always immediately return the cap to the bottle, and tighten the cap well.
Have fire precautions ready, just in case an accident happens.
Better Safe, Than Sorry!

The area of solder, around the hole in the board for the jack, may need to be buffed off. (Fine sandpaper in a tight roll, or a fingernail file using the fine side)

All areas that will accept solder need to be clean, and tinned.
Tinned, ...is the area is cleaned, a light spot of flux is touched around the rim of the hole, then solder is applied. The hole's rim then has fresh solder around it, and is ready to accept the DC Power Jack lead.

Be sure you have good solder joints! You may not see a cold solder joint, until you put the laptop back together, and the jack doesn't work. Then you get to take it all back apart, look at your solder joints, and go "OH".

This may help you in disassembling,

http://www.insidemylaptop.com/disassemble-sony-vaio-pcg-k-notebook/

you can use any laptop AC adapter DC output-16V and 4A (current). if its jack size natch your laptop DC jack.
if the adapter DC current less than 4A (over 2.5A at least) you should only make the battery charging without laptop turn on!!!
please take a rating let me know how much helped you thanks!

try looking on the top of the laptop, around the keyboard to see if there is anything that will pop off, they are very bad about hiding more screws in places like that.

you may have hardware problems an may need to change something inside. if you have the manual check the part of beep codes

Usually there is a side or a bottom part of the case where you can pop the hard drive out. My best advice is to refer to a manual or sony directly.

you will most likely need to replace the dc jack, which is the port where your charger plug plugs into...

To test if your dc jack is bad... Remove the Battery, Plug the Power cord into laptop then attempt to power on... If no lights turn on, no fan spins.. your DC jack is bad...
DC Jacks Cost $6 to $10 but you need to find someone experienced to replace it, or you might end up with a dead motherboard as well..

If the adapter is working, the problem could be the jack on the back of the notebook. The nice thing is most of the Vaio notebooks the jack is replaceable without having to solder the jack to the board. I would call SONY regarding the jack for a mode number and a picture. it's easily replaceable but requires the disassembly of the notebook.

It's probably the power socket on the laptop not the power jack on the AC adapter. You need to open the laptop by removing the casing screws. Then remove the motherboard from the base so a new socket can be soldered on.