No power at all

Is there anything but a dead power supply that would cause a total state of deadness in the box? I inherited a computer (and the former owner is out of town so I can't ask him about it) to rebuild. It looks like a pretty whiz-bang P3, but when I hooked it up and hit the switch absolutely nuthin' happened.

Yes I:

Checked the power cord/receptical. They make other dealies work
Checked the on/off switch on the back of the case. Nothing works in either direction
Checked the microswitch under the power cord-- it says 115
Checked the on/off switch on the front of the box by pulling off the front and making sure the switch really does things.
Patted its beige little head and called it a PREtty computer.


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Could be a bad motherboard. Of course, the first thing you should do is try another power supply. If still the same thing, unplug everything from the motherboard except the power connector from the power supply that powers the board and the switch wires. Meaning all the drives, USB, audio connectors etc... Remove the memory, video card, and processor and turn the machine on and see what it does. Most boards will beep because it can't pass the POST test, it doesn't detect the three things it needs to boot. If it beeps, try putting one back in at a time. Start with the processor, memory, and then the video card. It is possible its a bad hardware other than the board. If no beeps and it will not power on with all hardware unhooked except what it needs to turn on, then the motherboard is bad. If it does beep, just go back one by one all the way to the full system and see if you can pinpoint the  piece of hardware that stops the machine. Good Luck!!!
DecksawashAuthor Commented:
Wow, even the main box muffin fan won't go on if the motherboard is bad?
Sometimes it will, sometimes it won't. If nothing is happening, then the board is fried so bad that it is not transferring any power to anything. It is very possible that the power supply failed and took the motherboard with it.
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If the PC was not broke, before, it is likely you have a bad contact on your hands; removing and reseating all cards and connectors can help then.
Most likely culprits for a non starting computer :
-Power cable and switch
-power supply bad
-bad memory
-bad motherboard
-flat CMOS battery (coin like) replace it

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DecksawashAuthor Commented:
I wondered about the  CMOS battery because the box hasn't been plugged in in months, but again, thought that juice would always be obvious in the powerbox fan. I'll reseat cards/connectors today. I don't have any unused power supplies kicking around, though. I'll talk to my friend before I go messing with replacements, beyond the battery. My local Mom & Pop computer store is closed, but I might venture into the MegaStore for a battery today.

Errrr, if something was truely FRIED wouldn't there be some residual smell? This was one seriously dusty pup.

When I have fried monitors they definitely smell. Of course, flames come out of them. . .
>>    thought that juice would always be obvious in the powerbox fan   <<   you need to adjust on this matter, they are not so straightforward anymore; some levels are checked first, before starting the power supply. If they are wrong, it does  not start. The cmos battery should read 3 V, if in doubt, replace it; cost = 4$
A failed component doesn't always have a residual smell. Coil, capacitor, resistor, transformer, etc. could have just failed. Take the power supply somewhere and have them test it with a tester.
DecksawashAuthor Commented:
Shucks. The CMOS battery it was not. All cards/connections seem to be tight. I'm in a holding pattern 'til the former owner calls.

I tried waving my multimeter at it in non-contact voltage mode, but there's power stored in too many things to give me any clue what might be dead. The bugger buzzes at the power box and drives even when the box is unplugged.

>>some levels are checked first, before starting the power <<

Like an internal GFCI that works to minimize what gets fried when a componant fails? Good idea.
Y ou can diagnose the hardware by disconnecting/removing things.
A good start is  to have only mobo +cpu, video card, 1 ram stick, 1disk, kbd + mouse. if this setup starts, you can add devices later.
If it does not, try without kbd+mouse, and without disk.
if possible, try another power supply,video card , or another disk drive.(can be old ones)
DecksawashAuthor Commented:
Ah HAA! The AGP warning light is on-- so I got power. It might have been on all along, because I can't see the bugger unless I am lying down on the floor staring sideways into the guts.

I don't have a clue as to why the light would be on. It was the whizbang video card that the former owner was proudest of, so it formerly worked with this card.

Unfortunatly, I do not have the motherboard map for that particular motherboard in front of me, so I don't know if there are some qualifiers on the warning. And the only other AGP card around is in the box I am using to type this. What's safest-- putting *this* card into the non-working box to test it, or putting the card from the non-working box into *this* computer?
DecksawashAuthor Commented:
Found details for the vid card at AUSU, if that is useful
i would try first with another video card, or other ram; swapping the power suppply is also a good thing to try.
DecksawashAuthor Commented:
I swapped the video card with the one in my box. Works fine-- that is the card from the problem computer works in my box and the card from my box plays dead in the problem box.

The AGC warning light goes on as soon as I put either card in place. And I talked to the previous owner, and he says the box worked fine last week when he need to pull some info off of it.

Since the warning light goes on just fine, I am guessing that the power is okay and something is making the board think I have the wrong kinda card in here.

That being the case, I assume I should pay up here and re-open the question with another batch of points. Would that be the usual drill?

since it are both AGP cards, you can try a cheap pci video card for testing; be aware it can be a power issue too.
>>  Since the warning light goes on just fine, I am guessing that the power is okay    <<<  don't bet on it, if possible, try another Power supply (that from the other box maybe?)
DecksawashAuthor Commented:
Okay, I stole the power supply out of my husband's computer. No change at all. Warning light's on, nothing else working.

Hmmm. Pulled the AGP card, so there is no vid card in it at all and the warning light is *still* on.
DecksawashAuthor Commented:
Stuck a pci vid card in. No joy. Warning light on, box otherwise playing dead.

Can this be anything other than a dead motherboard?
well, the easiest way is to disconnect devices, and start with the minimum :
mobo+cpu + 1ram stick, video card, 1 harddisk, kbd + mouse
if still no joy, try without the disk, kbd + mouse.
if still no joy, culprits are mobo or cpu
DecksawashAuthor Commented:
I pulled all that stuff a couple of days ago, before I pulled the power. I guess it's time to take it in to my favorite in-the-flesh tech.
DecksawashAuthor Commented:
Russ the super tech pulled everything, too, and when he put it back together it worked. He says his workbench is magic. Obviously my floor, where I was working, is not. Box is loaded with graphics software (legal!) so we're all busy playing with it.

Thanks for the help.
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