Bad Power Supply?

[rkr1958]

We got back late last night from vacation. We were gone a week. We'd plan to stay two weeks at the beach but got chased back by Hurricane Ivan. Away, I shut down and unplugged all computers and other electronics before I left. This morning I plugged my computer back in and heard a couple of cracks and pops. When I pushed the power button ... nothing. I took the side panel off and I couldn't see anything burned or scorched. My question ... since I heard the cracks and pops when I plugged it in and before I hit the power button on the computer is this likely my power supply? I have an Antec quite case which comes with a 380-watts power supply.

[dxj40c]

Sounds like it might be the power supply. I've had one supply go out that made those noises but there was also a good amount of smoke and you didn't mention smoke or odor. I understand there is a brief power surge when you turn something on but I don't know if that applies when you just plug something in. But, it might. If you only have to replace the power supply, you are in pretty good shape, but even when the computer is off there is voltage going to the MB (when mine is off there is a LED that still glows) to power the CMOS I would suppose. That is why you sometimes to have to unplug the computer for 20 secs or so to fix some BIOS problems; however, that would only be 3V and I'm not sure that would be enough to make the noises you describe. Just hope your cracking and poping wasn't on the MB (if it was, it might be visible). I would just put in a new PS and see what happens. Good luck.

[rkr1958]

Thanks for the reply. Of course I unplugged and plugged back in and tried the power button several times and same result. However, after I'd had let it sit for 15-minutes or so, plugged it back in and hit the power button ... it powered on this time. Also, this time when I plugged it back in I heard something inside spin-up or power-up (not sure exactly what that was) which I didn't hear last time. (This spin-up / power-up sound was prior to hitting the power button and booting the computer).

Is there some sort of automatic reset on the power supply? Because all I did was let my computer sit for 15-minutes or so and it work this time.

[Capmaster]

Newer PCs have "ATX-style" power supplies. Parts of the motherboard remain powered all the time, instead of the old style AT hard-wired power switch.

If you live in a humid climate, or if the house is closed up for a while and the heat and humidity climbs, you could have gotten some minor dendritic growth across the copper traces of your motherboard. They might have already been growing some before you went on vacation. This is particulary true nowadays with the closer trace geometries and spotty quality control. It is generally an industry practice to put a conformal coating on the board, or tin the copper, which shields the copper from the air. However, I have seen many a motherboard with bare copper traces.

This happens faster when one is powered to a potential higher than the other one, but it could happen to an unpowered board, since copper corrodes quickly when high humidity levels and heat are involved.

In my business we often see gold migration which is caused by a similar, but different phenomenon, but the result is the same - a low impedance path between the traces which sometimes clears itself when the power supply is powered up that first time in a while. If it's enough current it could blow the breaker on the supply. Letting it cool down will reset the breaker, and the growths will often be gone

[rkr1958]

Capmaster: Wow ... I'm impressed. Thanks ... Hopefully that's it. It's been up and running fine now for a few hours.

[Capmaster]

Capmaster: Wow ... I'm impressed. Thanks ... Hopefully that's it. It's been up and running fine now for a few hours.

No problem
I think that might have been it then. I've also seen small solder whiskers cleared the same way. Too bad the low current signal lines don't clear as easily. But a power trace next to a ground trace ...yep. That works sometimes

I hope that's all it was