A somewhat ommon problem with laptops (and most other devices with a cord) is for the DC jack to become damaged. This can be due to a broken pin in the receptacle or cracked solder joints. The symptoms include no power even when plugged in and/or needing to position, wiggle, and apply pressure to the DC jack "just right" in order to get power to the laptop.

Damage to the jack is caused by improperly handling the laptop and cord. Here are some tips to prevent damage to your DC Jack.
  • Do not let the power brick hang from the laptop. The weight of the box in the middle of the cord causes stress on the DC Jack.
  • If you need to move the laptop, remove the plug. If you cannot do this because of a bad battery, hold the power brick so that there is no tension on the DC Jack.
  • If the DC Jack is at the back of the laptop, do not tilt the laptop backwards, if it is at the side, do not tilt it towards that side. If you need to see underneath, lift the laptop up or remove the plug from the DC Jack before tilting it.

The name of the game is to keep tension and lateral force away from the DC Jack. This advice can also be applied to other objects with a cord. For example, I don't like loaning power tools because they are often returned with the cord improperly wrapped. Tension on the cord where it enters the appliance is what causes premature failure of the cord. The picture below shows the proper way to wrap the cord around a power tool (The excess cord is not a handle, it keeps tension away from where the cord meets the tool)


Plug Wiggling



If you must wiggle and move the DC Jack to get power, you should have it repaired ASAP since moving the plug around can cause further damage, even to the point where your motherboard needs to be changed (Usually results in replacing the computer). Why? If you have ever seen any circuit board, you may have noticed the copper traces/lines on the front and/or backside. these carry electricity between components and the components are soldered to these traces. On a computers motherboard, the traces you see on the front and backside are not the only traces. There can be several layers of traces within the board. Wiggling the plug on a DC jack that has been worked lose from the board can cause the hole it is in to become larger. As it becomes larger, traces within the walls of the hole become exposed and can short across the DC jack pin, causing damage to other components in the board. In some cases, fixing the DC jack will cause these exposed layers to also be soldered to the jack, causing damage to the board.


This is a cross section of a solder pin through a motherboard through-hole. In this picture, only the top and bottom layers are electrically connected to the component pin using solder. This is illustrated by the brighter color of the top and bottom layers.


Due to stress & pressure on the component pin, the solder cracks, causing loss of electrical connection with the motherboard.


Wiggling the DC-Jack may cause electrical contact to resume. Doing this can also enlarge the motherboard through hole and cause contact with other PCB Layers, which causes a short. Most AC Adapters will shut down to prevent serious damage, though damage does occur which may show up later.


In this illustration, the motherboard though-hole has been enlarged, causing the other PCB layers to be exposed inside the through-hole. It is unlikely that this can be repaired though the owner and the repair tech probably do not know this yet.


This illustration shows a repaired DC Jack. The solder has been re-flowed and contact with the motherboard has been restored. Unfortunately, the repair is too late. The exposed layers have been soldered to the component pin and the motherboard is now shorted and permanently damaged. Time to replace the motherboard.