PC Power Supply Bad?

[lneal]

Quick question for the TB geek squad: One of my pc's is doing something I've not seen before; the power supply fan runs but the computer is otherwise as dead as a door nail. Tried unplugging and replugging the AC cord but no change. It will not boot at all, just sits there with the PSU fan running constantly. This particular machine was a workhorse before we got this laptop, as reliable and fast as a pc can be. We had a power brownout yesterday while the pc in question was running. I suspect it may need a new power supply. Agreed? Any other ideas before I plunk down the beans for a new power supply?

 

[sloasdaylight]

Could be your power supply, it could also be your motherboard.

Your motherboard should have a little green light that will light up if it's connected to a power supply. I'd tell you to check it, but unfortunately in this situation it will probably not be lit.

Your best bet would probably be to buy a new power supply and see if that fixes the problem. If it doesn't, then replace the motherboard as well. At that point though you may very well need to replace the whole system, because if there was any kind of surge, it could have gone through into your HDDs, GPU, CPU, etc.

 

[lneal]

I haven't taken it apart yet but will probably do so tomorrow and will check for the light. Thanks for the help.

 

[sloasdaylight]

Well, like I said, the PSU needs to be connected to your wall and on in order for the light to be on. The fact that your PSU fan comes on makes me think that it may be a problem with your motherboard.

 

[lneal]

It just occurred to me I have a friend who probably has a PSU I can try to see if that's it. If it's the mobo I wouldn't be too upset as this machine has served me well over several years. I built it in about 2007 and it was the main pc here at home but I had put it in my studio to be used for mastering, etc. It may be time for a rebuild...

 

[Jake Saint]

PSU fan coming on in general = good PSU, indicating problem is somewhere else. i'd say it's safe to assume it's the mobo.

 

[T-Bird]

Hi.

Before You somewhat aimlessly swap the PSU, look for bulging or leaking electrolytic caps on the motherboard (or in the PSU for that matter).

Certain PSU's have tendency to keep the supplier in the business of supplying new PSU's though .

Regards
Sam

 

[lneal]

Well, I took the cover off when I got in from work, fiddled around with connectors and gave it as general inspection and found nothing obvious. Hooked it back up, turned it on and it booted right up, no problem. I'm posting this from the computer in question. Strange days.........

 

[Bob Lee (QSC)]

It's not unusual for a loose connection to cause that. I've had it happen a couple times with desktop computers. One of the first things you check should be to make sure all the connectors are seated well.

It's good that it was just something that you could fix by fiddling with connectors. If all the connections were good and the problem remained, you can buy PS testers (or borrow one if you have a suitably geeky friend) for around $20, maybe even less, that plug into the PS, emulate the "on" command from the mobo, and have LED indicators on all the supply bus voltages to verify that they're live.

 

[Sneakypete]

I would also suggest removing the motherboard RAM (dimms?) giving the edge connectors a wipe with a clean rag and maybe a tiny spot of Deoxit and then firmly re-seating them. The motherboard definitely won't start up if it's not 'seeing' the RAM and I've had a few instances of that over the years.

 

[Funky Ghost]

If you had a brown out that means you probably hard booted. That can cause registry errors galore.

Have you tried to install a boot disk to see if you go beyond a blank screen?

 

[lneal]

It's not unusual for a loose connection to cause that.

This is it, Bob. I left it running overnight and it was back to the PSU fan running next morning. I whacked the case on its side, the fan stopped, hit the start button and it fired right off. When I have the time I'm gonna reseat all the connectors and go from there. Thanks for the ideas everyone. Funny though how this machine is the fastest and most reliable PC I've ever had (built it myself) until that brownout. Kinda makes ya wonder.............