- Loosen the case screws on the electrical device. Open the case to expose the wiring behind the DC power jack.
- Plug the power cord into an electrical outlet. Turn on the multimeter and set the scale to "Volts DC." Place the black multimeter probe on the outside metal sleeve of the power cord tip. Place the red multimeter probe inside the center hole on the power cord tip. Check the voltage measurement; it will be equal to the rated output voltage of the power cord.
- Unplug the power cord from the electrical outlet, and remove the red probe from the power cord tip. Cut one of the wires off the power cord tip, and strip half an inch of insulation from the cut wire. Pull the wires apart until there is a 4-inch separation between the stripped wire end and the power cord tip.
- Attach the red probe to the stripped wire and plug the power cord back into the outlet. Check the multimeter display. If the voltage reading is zero volts, cut a piece of electrical tape and place it on the wire that is still attached to the power cord tip. If the voltage reading equals the power cord voltage rating, cut a piece of electrical tape and place it on the insulated part of the stripped wire.
- Remove the probes from the power cord, and switch the multimeter scale to measure "Ohms." Cut the remaining wire off the power cord tip, and strip the wire end.
- Place the red multimeter probe on the center connector of the DC jack. Touch the black probe to the exposed metal end of one of the wire leads behind the jack. Check the multimeter display. If the resistance measurement equals zero ohms, cut the wire off the back of the DC jack and place a small piece of electrical tape on the insulated part of this wire. If the resistance measurement is greater than zero ohms, cut the other wire connected to the jack, and place a piece of tape on the insulated part of this wire.
- Turn off the multimeter and remove the probes from the electrical device. Cut the remaining wire from the back of the DC jack. Use the screwdriver to remove the jack from the electrical device.
- Insert the wires from the power cord into the hole where the DC jack was previously installed. Twist together both wires that have a piece of electrical tape on them, and solder the connection. Place a piece of electrical tape over the metal parts of this connection.
- Twist together both wires that lack a piece of electrical tape on them, and solder the connection. Place a piece of electrical tape over the metal parts of this connection.
- Replace the electrical device's case, and tighten the retaining screws to close the device up.
How to Fix a Broken DC Jack
Many direct-current devices intended for household use have a detachable power cable. Over time, the electrical contacts on the device may become worn or loose. When this happens, the device may lose power intermittently, or may cease to function altogether. If the input jack becomes loose or broken, it may be necessary to remove the jack and hard wire the power plug to the electrical device.