I had a Dell Inspiron laptop come to me for repair with intermittent power problems. I first check the AC adapter and it checked out fine. Next I moved the AC plug around in the DC power jack and found that there was a faulty connection. I disassembled the laptop down to the motherboard.
I noticed that there was very bad lint and dirt build up in both of the fans on this laptop.
I proceeded to blow out the laptop with compressed air and clean up the unit as best I could. After that, I got out my digital multi-meter and set it to sound so it would beep when I did my continuity check. I tested the points where the power jack positive and negative went through the PCB and there were no good connections. I then proceeded with a visual inspection of the solder joints. I found that the solder joints had cracks in them. I got out the soldering iron and reflowed the solder on the joints . I used the multi-meter to check again and now I had good connections from the power jack top side through to the bottom of the PCB. Next picture is after I soldered the joints.
I put the laptop together just enough to boot it up and test. It booted up fine, so I moved the AC plug around in the DC power jack to check my work. It performed as it should while I moved the plug around. I then proceeded to put the laptop back together. I booted it up to the operating system and checked to make sure everything was working ok. I let it run a couple of hours to make sure it was a good repair job. Everything was in working order so I gave it back to the customer.