Power problems

Status
This thread has been Locked and is not open to further replies. Please start a New Thread if you're having a similar issue. View our Welcome Guide to learn how to use this site.

jbezweb

Thread Starter
Joined
Jan 2, 2005
Messages
140
I have a PC that is not pwering up correctly.

If the power switch on the back of the pc is on and the pc is plugged in it will turn on without me having ot press the power button in the front.

Also the pc doesn't actually boot up. The fans turn but there is no beep , just nothing.

This is weird. It worked fine and then one night I turned it off, then the next day when I went to turn it on...the described situation.

It is a Socket 754 Athlon 64, 2.4 Ghz, 2000mhz FSB, 1Mb cache, 1Gb DDR 333 RAM, Geforce FX 5200 256Mb Video card.

Any help is appreciated.

PS I have removed every component (except the motherboard) from the case and reseated it.
 
Joined
Nov 25, 2005
Messages
437
Sounds like the front power button is jammed in the ON position. The power button on the front of the case is a momentary switch; when you push the button, it completes a circuit momentarily. As soon as you release the button, the physical contact is lost, but circuitry on the motherboard locks the power on. That way, there is no current running through the switch (small as it might be) any longer than necessary.

First, remember to take all normal and static electricity precautions; you don't want to do any harm to yourself, your system, or your property.

Next, UNPLUG the system from the back of the PSU, or from the wall. Then, open the case so you can see the back of the front power button. Once you've done that, trace the two wires from the back of the power button down to the motherboard. On two of my systems here, one wire from the power switch is yellow, and the other is white. On another case, one wire is blue, and the other wire is white-and-blue. I don't have the time to check any other systems here, so you'll have to check carefully to be sure you follow the correct wires down to the motherboard.

The pins where those wires connect are probably labeled "PWR", "PWR SW", or something similar. Look closely; use a flashlight and magnifying glass if need be.

Make a note of which position the wires are in, so you can put everything back the way you found it. Then, gently remove ONE wire; there is NO NEED to remove both of them. BE SURE YOU KNOW WHERE IT BELONGS BEFORE YOU REMOVE IT, so you can put it back in the proper position later.

While the wire is disconnected from the front panel power button, push the power button a few times to see if it feels normal. If it is jammed internally, you might be able to free it, so you can continue to use the system while you get a replacement switch or a new case, if the case is still under warranty. If nothing you do will make the switch functional again, at least you'll know you where the problem is.

For the next test, do NOT reconnect the wire from the front panel switch to the motherboard. Simply leave the wire dangling in air, or tucked out of the way where it won't get damaged, or damage anything else. If you prefer, you can put a piece of tape (masking tape, clear tape, electrical tape, a band-aid) over the end connector to insulate it, though that really isn't necessary.

Next, plug the power cord into the PSU, and flip the switch on the PSU to the ON position. The power should NOT turn on, because you've temporarily opened the circuit from the front panel power switch to the motherboard.

IF THE POWER TURNS ON while the front panel wire is disconnected, you most likely have a defective motherboard; something could be physically shorting power to the board (a loose screw that dropped into the case), or some internal circuit is getting a signal it shouldn't be getting ALL the time, which is why power is always applied once you turn the switch on the PSU to the ON position.

If the power does NOT turn on while the wire is disconnected, that indicates that the front panel power button is malfunctioning, and probably jammed in the ON position.

Once you've diagnosed the problems with the power button, UNPLUG THE PSU again, then reconnect the wire you removed. When you're sure everything is back to normal, plug the power cord into the PSU, and tun the PSU power switch ON. If you've corrected the problem, the power WON'T go on UNTIL you push the front power button. If the power turns on IMMEDIATELY, you'll know the front panel button is still jammed (if you haven't already decided the motherboard itself is the culprit).

This is a simple procedure, so take your time diagnosing this; you want to get this right the first time. Keep safety in mind, and think about what results you expect BEFORE you take the next step.

Happy troubleshooting; let us know what you learn.
 

jbezweb

Thread Starter
Joined
Jan 2, 2005
Messages
140
Thanks Sammy,

I have tested the button the way you suggested already and the power still came on. I will have to try and reseat the motherboard and if that fails, I think it is still under warranty.

Thanks again.
 
Status
This thread has been Locked and is not open to further replies. Please start a New Thread if you're having a similar issue. View our Welcome Guide to learn how to use this site.

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

As Seen On
As Seen On...

Welcome to Tech Support Guy!

Are you looking for the solution to your computer problem? Join our site today to ask your question. This site is completely free -- paid for by advertisers and donations.

If you're not already familiar with forums, watch our Welcome Guide to get started.

Join over 807,865 other people just like you!

Latest posts

Staff online

Members online

Top