# PC Dead After Being Unplugged



## jsudds (Sep 28, 2005)

Hi!

My desktop PC won't turn on, but I'm not sure if the cause is a faulty power supply or something else. It's an older model, an HP Pavilion a820n.

I went away for vacation over Thanksgiving weekend. Before leaving, I powered down the computer, then for extra precaution, I turned off the surge protector power strip and unplugged the strip from the wall. (I did not unplug the computer from the power strip.) I figured that the computer would be least vulnerable to power surges if it was completely unplugged.

When I returned from vacation & plugged the strip back in, the other devices on the strip (monitor, router, etc.) all worked, but the computer would not boot up. Several hours later, I tried again and it worked the first time I pushed the power button, so I didn't think any more about it.

Just got back from another trip, and again when I plugged the strip back in, all the devices work except for the PC tower. It's been over 12 hours and it still doesn't boot up when I press the power button.

I unplugged the PC from the strip and replugged it in; I unplugged the power cord from the back of the PC and plugged it in; I tried plugging it directly into the wall receptacle bypassing the strip; etc.; but still can't get it to boot up.

Other devices plugged into the strip still work, so I think it can't be the strip.

One possible clue: The green light on the jack where you plug the LAN cable into the back of the PC tower is flashing, which I believe is normal to indicate that the PC is receiving a signal from the cable modem. But I'm not sure this light would flash if the PC was completely without power.

Second clue: There's another green light, a round light right below where the power cord plugs into the back of the PC, that is also flashing in unison with the first green light I mentioned. The tower resides in the cabinet under a computer desk so I don't normally see the back of the PC and therefore don't know if this light normally flashes this way.

Third clue: Both lights are flashing in unison about twice per second. When I disconnect power from the PC, either by pulling the power plug out of the back of the PC, or by turning off the power strip, both lights continue to flash but at a slower pace. About once per second.

Since this has now happened twice and the computer is very old anyway, I am considering replacing it with a new computer. But even if I do that, I'd like to be able to boot up the computer to retrieve the data from the hard drive.

Does this sound like a problem with the power supply? If not, do you have any other suggestions on what may be the cause and how to fix it?

Any suggestions would be welcome.

Thank you for your help!


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## grimx133 (Jan 15, 2008)

Sure does sound like a power supply problem. You can test it with a multimeter.
http://www.techsupportforum.com/f210/test-your-power-supply-with-a-multi-meter-151526.html 

If you do replace it with a new computer, there's no need to fire up the old one.
The hard drive can be removed and read in another computer, whether with an 
internal install or an enclosure, either usb, e-sata, or firewire. Then the data can 
be copied off.


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## jsudds (Sep 28, 2005)

Hello again. I'm sorry it took me awhile to get a multimeter and get the time to do the testing. I followed the testing instructions and here are the results:

Testing the DC Voltages:
1. Pin 9 was ~3.0.
2. Pin 14 was ~2.0.
3. Pressing the pc case Power On switch and PS_On did not drop to ~0V. The reading bounced around a lot between ~1.8 and ~2.3 but never settled on a constant reading.

Actually, the readings in all 3 steps bounced around and never settled on a constant reading, but the ones for step #3 varied the most.

So I skipped steps 4, 5 & 6.

Testing for Continuity:
1. None of the black wire pins produced a zero reading. Some produced a reading of 1.0, others were 0.1.

That's where I stopped.

Oh, the green power light on the back of the pc case is still blinking as I stated in my first post, and I forgot to mention before that there's a ticking sound coming from the PSU - it ticks in unsion with the blinks.

So does it sound like only a bad PSU, or something worse?

Thanks!


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## grimx133 (Jan 15, 2008)

Sounds unstable, among other things, see if you can borrow one for testing purposes.
There's a psu sticky, it's a good read.
http://www.techsupportforum.com/f210/power-supply-information-and-selection-192217.html


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## m.c.robinson (Dec 29, 2010)

Mine does the same. The easy fix is pull out the mains power plug, remove the side panel, disconnect the main power connector from the motherboard and then plug in the mains connecter. The green led should not be flashing and the ticking should have stopped. Now plug in the motherboard connector and switch on the pc as normal.


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## Stopdroproll (Dec 22, 2010)

I had the same thing with HP a350n. Wouldn't boot up and the green light was blinking on the back of the PSU. I bought a new PSU and installed it. But it looks like the dead PSU also took out my motherboard.


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