Laptop Power problem

     1. Laptop Power problem: 

1.  When your Laptop power problem you should check/change AC power adapter/power cable.

1.   If no problem cable/AC power adapter Check/change.
2. If    AC power adapter is OK  Then check your mother board power mosfet.
3. . If the crystal damage change the crystal.4. Check all options but problem not solve. You should go to a computer servicing center.

AC power adapter

How the AC adapter works

The most common type of AC power adapter involves a small box, with one wire to go to the computer and another wire to go to the wall. There is usually an LED light on it, to tell you that it is on. (Is it lit on yours?) By the way, Apple notebook power adapters often have an LED that is actually built into the side of the computer, not into the adapter box, so obviously it wont light up when its not connected to the computer.
The power adapter box does several things. It lowers the voltage from the walls 120 volts AC to typically 19 volts DC (it will be labeled with the exact voltage). It includes some power noise filtering. It often includes an automatic circuit breaker or overload detection. If this gets tripped, you can generally reset it if you unplug it from everything for a few minutes.
You can measure the voltages on your AC adapter with a multimeter. When it is unplugged from the computer but still plugged in to the wall, it is normal to find that the voltage may be 1 to 3 volts higher than the printed output rating.

Troubleshooting: AC Power adapter LED is off when you plug the adapter into the wall but not into the computer

Has it been overloaded? Is the power strip turned on / is the outlet working? Is the cord from the adapter to the wall fully plugged in on both ends (try wiggling)? Your adapter may be fried- try borrowing an indentical adapter from a friend and seeing if that one will work in its place (but do not plug it in to your computer, or you might fry your friends adapter).

Troubleshooting: Check output voltages with a volt meter/multimeter

For those of you with circular connectors, your task is easy. Measure the voltage between the inside and the outside. A diagram on the adapters label will tell you which should be positi
ve and negative
For those of you with the 3-pin Dell power connectors, I dont have a diagram for you yet, sorry. If you try measuring each of the three possible pairs of pins, you should get 20 volts between one of the pairs.

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