Diagnosing the DC Power jack problem.

Doing a correct DC Jack diagnostic is very important. Tearing down a laptop, doing the repair, and then having it not work can be really frustrating. A lot of the repairs we do are sent through the mail and I get them assuming they need the repair. That isn't always the case.
The first thing I do is check the ac adapter (Testing your ac adapter). You can get a simple volt meter from radioshack that will tell you is your ac adapter is giving off the proper voltage. Make sure to give it a wiggle because sometimes the wiggling to make it charge can be a break in the ac adapter.
If the adapter checks out I take a small flathead screwdriver and see if the actual jack is loose. These can be slightly loose from totally broken off and still have the same dc connection problem. If the jack is loose and the adapter checks out I try to get it to power on. I do this because I like to know that it can power on before I start working on it.
You also want to take out the battery and plug in the ac adapter. If the laptop can power on give the ac adapter plug a wiggle to see if the laptop shuts down.
Some of the main symptoms include:

• Move the power plug and the laptop loses connection
• Broken or cracked dc jack
• Laptop won't charge but worked on battery
• Power LED and battery LED flicker when the adapter tip is moved
• Battery won't charge
• Sparks come out the back of the laptop
• Melted or very hot ac adapter tip

I had a laptop come in this week and I don't think it's the dc jack. The customer was pretty sure it needed a dc jack repair but after a diagnostic I thought differently.
It won't power on even with the battery, just suddenly stopped working, dc jack isn't loose, and ac adapter checked out.
If you don't have any of the above mentioned symptoms you probably don't have the dc jack problem.
Even if the laptop isn't charging you don't necessarily have a dc jack problem.
Another common symptom that isn't the dc jack is when the laptop just won't charge the battery. I've seen a few laptops that won't charge the battery but work just fine on AC. These laptops have some type of motherboard problem.