Frequently Asked Questions
Q: How do I troubleshoot power supply issues?A: Because there can be a variety of causes for no power to the computer, several troubleshooting steps may be needed to diagnose the problem.
- The outlet into which the computer is plugged may be inoperative.
- The surge protector you are using may be inoperative.
- The power cable may be loose or damaged.
- An internal device may be damaged.
- The power supply may be inoperative.
- The power switch may be inoperative.
- The motherboard may be inoperative.
Power to the computer
There may not be a consistent flow of power to the computer.
- Verify that the outlet into which you are plugging the computer is operational.
- If you have the computer plugged into a surge protector, plug it directly into the outlet.
- Verify that the power cable is plugged securely into the back of the computer.
- If you have a monitor with a removable power cord, swap the power cords between the monitor and the computer.
Note: If you recently added a new hardware device before experiencing the no power issue, turn off the computer, and remove the newly added hardware. If there is still no power, reseat all of the other cards and cables in the computer to verify that all other devices are seated securely.
Resolving power supply issues
External device conflicts
There may be an external device causing the computer not to turn on properly.
- Before continuing, verify that the computer is turned off.
- After you have established that adequate electricity is going to your computer, verify that the voltage switch on the back of the power supply is set correctly. The small red switch is to be set to the 115-volt (V) setting.
- Remove all external devices except the monitor, and then turn on the computer. If the fan on the back of the computer now spins, turn off the computer. Plug in the external devices one at a time, and then turn on the computer after each device is added.
Note: If you removed all external components and the fan on the back of the computer does not spin, the issue is with something inside the computer.
Internal device conflicts
The following steps help determine if the issue is a damaged or badly seated component.
- Verify that the computer is turned off.
- Remove the case from the computer.
- Remove all of the red, yellow, and black power connectors from each floppy disk drive and ROM drive and the tape backup unit (TBU) that is in the computer. Remove all power connectors from the motherboard. The only device that needs to be connected to the power supply is the hard disk drive.
- Press and hold the test switch for five seconds on the power supply, and then verify that the green light on the power supply comes on.
- If the light comes on:
- The power supply is good and something that was plugged into the power supply is causing the computer to not turn on.
- Plug devices in one at a time, testing with the test switch between each device to determine what is causing the power issue.
- If all devices are plugged in and the light is working, the connections may have needed to be reseated, or it is possibly a power switch issue. Go to the Power Switch Section for additional troubleshooting steps.
- If the light does not come on:
- Disconnect the power from the hard disk drive, and then plug in power to the CD-ROM drive and determine whether the light comes on.
- Confirm that power from the power supply is connected to the motherboard. Remove all cards and cables from the motherboard, and press and hold the test switch for five seconds on the power supply and determine whether the green light-emitting diode (LED) comes on.
- If the LED comes on, put the devices back in one at a time, testing between each device to determine what is causing the issue.
- If the LED does not come on, replace the motherboard.
The power switch may not be functioning properly.
- You may need to open the case, and then readjust the power switch.
- Locate the control panel inside the computer, and then remove any screws holding it in place.
- Turn on the computer with the control panel by pressing the button on the control panel that corresponds to the power button. If the power supply fan spins or the computer turns on, put the control panel back in its place. Turn on the computer again.