power supply

[indianaguy]

working on a friends pc, the pc would not turn on so I replaced the power supply, now it turns on when you plug it up without using the on/off switch but doesn't post.

would this be a faulty power supply or something else?

 

[BadBigBen]

that last sentence of yours is way to confusing, I had to read it at least 4 times before I understood what you where saying...

to answer the question:

yes it could be a bad PSU... which leads me to ask, when you replaced the PSU, was the replacement NEW, used and known to function?

but it could also be mainboard, CPU, ODD, HDD, and a gamut of other things...

now, I would unplug any devices, e.g. HDD, DVD, PCI cards, PCIe Cards, USB devices, etc. just leaving the ONE stick of RAM (unless it is DUAL channel then two sticks or triple channel then 3 sticks), CPU and GFX card, and then attempt to POST...

if it does not, then replace the PSU with ONE that is KNOWN to function....



Ben
"If it works don't fix it! If it doesn't use a sledgehammer..."
How to ask a question, when posting them to a professional forum.
Only ask questions with yes/no answers if you want "yes" or "no"

 

[indianaguy]

This was a new psu. I guess I need to be a little clearer as to the issue, When I plug up the psu it automatically comes on without pushing the case on/off switch to power the pc up. While it is powered up it will not post. The power supply should not power up as you plug it in.

 

[mscallisto]

Are you absolutely certain the psu is the correct model and you properly connected it?

Have you checked for any visible shorts?

sam

 

[tlcscousin]

Have you checked the power button is not shorted or stuck?

 

[BadBigBen]

sometimes when PSU go out, they tend to take out other components along with it...

this is the reasoning behind removing every non essential device...

once it has been stripped down, cleared the CMOS, and it still behaves as you describe then I am more inclined to believe that it is the mainboard that is shot...


Ben
"If it works don't fix it! If it doesn't use a sledgehammer..."
How to ask a question, when posting them to a professional forum.
Only ask questions with yes/no answers if you want "yes" or "no"

 

[goombawaho]

To be sure, pull the motherboard out of the case, put it on a piece of cardboard, tile or wood. Then plug in the power supply and have everything else optional disconnected. Only have PSU, processor, memory and video card (if not integrated) connected.

Use a screw driver to short/start the computer - NOT the power switch.

This will rule out the power supply, other components and the power switch. The motherboard and cpu would still be in question.

To check the motherboard, pull all the memory and see if you get any warning beeps. No beeps, but with CPU fan turning probably means dead mobo.

 

[rclarke250]

Check the system board for blown caps, or bulging leaking caps.

http://www.badcaps.net/

here you can see what to look for. Also depending on how it is set in bios, if last state after ac loss is set to power on, once ac power is restored the system will attempt to power on, no switch needed.