Fault 1: a NEC VA23D notebook, when the external power adapter, the laptop on the battery indicator shows the status of the machine work, need to remove the plug several times before they could return to normal. This failure was more serious, and finally, no matter how remove the plug, laptop can not use the power adapter. When the battery runs out, the boot and no respond.
Analysis to solve: As notebook battery can work under the basic notebook itself does not determine much of a problem, so first check the focus on the power adapter. Remove the plug because of the need many times can the laptop to work, suspect the power adapter interface or power cable has poor contact situation. Then test the output voltage with a multimeter, and a hand twisted cord, but the output voltage is normal multimeter instructions, it seems the power adapter is no problem.
Problem or in a notebook, carefully disassemble the notebook, carefully observe the power connector in the vicinity of the components found in the interfaces have a presence Weld resistance phenomenon. According to circuit analysis, this resistance is an insurance, resistance, power adapter output current through the resistor to the supply of motherboards. Because of this resistance appears Weld, and plug the power head will Weld Department jitter occasionally connected to main board power adapter supplied by the current. But Weld's production to increase contact resistance, leading to fever increased, but the heat also caused the phenomenon of increasing Weld, and so a vicious cycle, eventually leading to solder joint completely off, causing the failure. After the repair welding joints (Figure 1), notebook finally back to normal.