Power On Problem

I received this pc from a friend that was upgrading a couple of years ago. It's a 800Mhz P2 with a ATX Power supply that has a on/off switch.

I noticed from the start if I tuned the pc off from the front power switch and then tried to turn back on it would not power up. Sometimes I could wait 15 or so minutes and it would work. Sometimes I would have to leave it for hours. I got to the point that I just left it on all the time. I moved last week and it came right up when I installed it in my new home.

Last night I turned it off and it still will not come back up. I suppose it could be the PS, but thought it unusual that it has always had this problem.

Any ideas??

 

I'd bet money on it being the power switch itself.

With ATX power supplies the on/off swith is usually just a very cheap little switch that makes a circuit when depressed. The switch is connected to a jumper on the motherboard. With the older AT power supplies the switch was a large mechanical device that connected directly to the power supply.

Simplest solution, disconnect the power switch wires (that come from the PC case's front panel) from the motherboard, by removing their connectors from their jumper pins on the motherboard.

Then move the wires from the reset switch to the pins the power switch was connected to.

You can then use the reset switch/button as the power switch. Obviously you loose the reset functionality, but that's no great loss.

The next easiest alternative is buy a new ATX case.

 

Thanks for the reply!
I removed the PS SW wires and replaced with the reset sw wires (all coming from the front of the pc). No dice
Any other ideas?

 

What is the Wattage of the power supply?

Try disconnection everything from the motherboard except the Power connector CPU, RAM, Video and power switch. (that is disconnect the drives, cards (sound, modem etc), USB connectors, other front panel connectors, mouse and keyboard).

Then try to boot. You should get the initial POST screens (white writing, black background, and then the boot up should halt at a "no OS found" warning.

If it boots, shut down and reconnect something. Boot it again. Repeat this until you find the device that is preventing the system booting.

If it won't boot, you probably have a motherboard or power supply fault.

 

Removed all componants except video and still will not attempt to boot.
Guess the PS or MB crashed. Will check those out.
Thanks for the suggestions.

Joe

 

To test the switch, just disconnect the wires from the switch at the mobo and use a small screwdriver to short the 2 pins momentarily. If the computer boots immediately, you've got a bad switch.

I'd prefer this test to juggling the other wires when troubleshooting remotely, although if the computer booted with reset wires it would also indicate a bad switch; but since it didn't, I'm not so sure.