I wanted to change the power cord for my laptop from a straight connector, to a 90 degree connector. Fear of snapping the straight connector off was my motivation for this project.
Step 1: Find a compatable connector
My HP Compaq 6720s had a strange power connector that has a spring in the middle to connect the pin. I found the correct one at Best Buy. Its made by Jensen. The power adapter itself will not be used. We are using just the supplied tip.
Step 2: Test
Shove a small wire into the new connector. Now with a multimeter, you can find out which of the two prongs is the center one or positive. You can use a battery and a light bulb to do the same process.
Step 3: Solder
Now solder the center wire of your original power cable to the positive pin, and the outer ground wire to the other. I used some heat shrink on each wire, and superglue to ensure it wasn't going to move.
Step 4: Test and Done
Using the same wire pushed into the center of the connector, I tested for voltage. It should measure close to the voltage labeled on the power brick.
Before the final layer of heat shrink, I cut off the plus and minus molded onto the sides of the plug with a razor blade. They were labeled wrong anyway for my application. Now heat the big outer piece of heat shrink.
Lastly I used a black sharpie to finish it off. I might try some black vinyl paint by duplicolor, the sharpie is turning purple.
Success!!! Now I can sit in my favorite lazy boy chair, without trying to break the power connector on the arm of the chair.