DC jack on the laptop motherboard

The DELL motherboard DC jack with third wire center pin

The DC jack soldered at the laptop motherboard sits at a particularly risky position. It’s mechanical design should withstand sudden jolts/ impulses caused by the DC plug suddenly pulled away.

Whatever the design quality, DC jacks can come loose from the printed circuit board when enough force is applied.

For brands like DELL - the DC jack already has a notorious reputation. DC jack repairs, replacements or even motherboard replacements are not unheard of. Probable cause? Most likely lack of engineering time or poor manufacturing quality.
 







 

The 3rd pin in the laptop DC jack

When the laptop still runs from the AC power adapter, but the battery is not charging most likely the “3rd wire” identifying the AC power adapter is not making contact, because:

-    The third pin in the DC jack isn’t making proper contact with the plug
-    The third pin soldering of the DC jack on the motherboard is loose

Slowly turning / moving / re-inserting the plug in the DC jack can prove a problem with the DC jack. BIOS setup screen for the AC adapter (if applicable) can be of great help for diagnosis of contact problems. Most likely solution is DC jack re-soldering or DC jack replacement. In this case the motherboard needs to be disassembled.

Other possibility is a close inside inspection of the DC jack center "3rd wire" hole. The metal clips inside the DC jack embracing the center pin from the plug could be bend outward / worn down. Either the center pin of the plug should be thicker or the inside metal clips bend more inwards.
 

Intermittent DC jack power problems

When laptop power is intermittent when the DC jack is moved - most likely one of the power pins came loose from the motherboard. When manufacturing quality is poor, it doesn't need much for this problem to occur. Also in this case the motherboard needs to be disassembled for re-soldering or replacement of the DC-jack.
 

The docking station / port replicator test

Not sure if the DC jack is the problem? Test if your laptop battery charges again using a docking station or port replicator. Most laptops have a large docking station connector underneath or at the back. These pins include the power lines for powering the laptop.

If the laptop battery charges again using the docking station /  port replicator most likely the DC jack is loose from the motherboard or power input circuirty on the motherboard has died. A docking station can be the alternative to an expensive DC jack repair.

Back to the laptop battery charging diagram.