This is my wife's Asus Eee PC notebook. It recently began shutting down spontaneously. An Internet search suggests others have also had this problem. Often the suggested fix has been simply to get a new computer. But, in our case, the problem turned out to be a frayed cord inside the strain relief, which is a very inexpensive problem to fix.

My wife noticed her computer seemed to cut out when she happened to bump the power cord. There is a blue LED on the power converter brick that indicates it is working. While she was showing me how moving the power cord often caused the computer to shut down I happened to notice the blue LED went out at the same time. Wiggling the strain relief on the load side of the power converter frequently caused the blue LED to light again.

Tools used--
Hacksaw
Screwdriver for prying
Sharp knife
Soldering iron
Multi-meter
Third hand to hold wires for soldering

Materials--
Solder
Electrical tape

Step 1: Crack the Case

I decided to crack the case on the converter brick. I used a hacksaw to cut along the seam. Then I used a screwdriver to break the rest of the case seam.

Step 2: The Case Opened

This photo shows the case fully removed from the power converter. There really are no exposed conductors that might hold a shock hazard. The white wire has a nick in its insulation, but this did not seem to be the problem. There was no evidence of burn marks, nor of broken strands of the wire, itself. I decided to cut about two inches of wire around the strain relief out of the cable. Since I could not access the points on the circuit board where the black and white wires attach, I decided to cut about midpoint in the visible portions of the black and white wires. I stripped some of the white and black insulation from the wires connected to the circuit board. I soldered stripped ends of the freshly cut cable to the white and black wires.

The connector that plugs into the computer is supposed to be center point positive (+), according to the label on the side of the converter brick. Do some checking with an electrical meter to be certain the polarity is not changed during reconnecting the cable.

Step 3: Soldered and Insulated

The ends of the cable have been soldered to the remains of the black and white wires after they were cut and stripped. I have used some green plastic electrical tape to insulate both as well as possible.

Step 4: Close It Up and Test

I wrapped the case with black electrical tape to hold its two halves together. I forced hot glue into the opening where the strain relief had been and held it steady until the glue solidified. Notice the blue LED lights as it should now.

I confess I accidentally reversed the polarity when I soldered the cable to black and white wires coming from the circuit board. It was easier to do than one would think because the internal construction of the cable was counter-intuitive. But, now the power converter that seemed to be defunct works. Whereas my wife's notebook computer worked fine when on battery power only, it now works fine on AC power without any spontaneous shut downs.

What was the problem? A simple break in a wire inside the strain relief should not have caused a spontaneous shut down. The computer should simply have drawn from its battery. But, a short in the strain relief seems more likely to cause both the power supply and the computer to shut down. I say that because shorting a gray wire to ground on an ATX power supply for a desktop computer causes an immediate shut down by dropping a critical CPU voltage below a minimum standard. (Deliberately shorting that gray wire momentarily can be used to make a reset button on a computer that has no reset button.)

The most surprising thing about this solution to a spontaneous shut down problem is that the cause was not something inside the computer, but something in the power supply. Spontaneous shut down issues are usually due to an overheated CPU, which can be caused by dust plugging the cooling fins, or to a faulty RAM memory stick. An exception for a desktop computer is that a faulty power supply often causes shut down problems, but a desktop does not have a battery from which to draw operating power like a notebook does.