Help.....my PC has died!

[harvest1]

I decided to plug in my new mobile via USB a few moments ago. I used the front USB port, and the computer said something about a power surge. The mouse froze (which was USB) but everything else seemed to be working okay.

However when I shutdown, it froze just before the computer completely shutdown. Like a fool, I just pressed the power button for 4 seconds with a vierw to re-booting.

Now when I switch the PC on, I get absolutely nothing. All the fans work, and the HDD seems to be functioning, but it doesn't seem to boot and I can get no display.

Is there a fuse/switch somewhere that needs resetting? Or do I need a new Motherboard? I can't believe something as simple as a mobile phone could kill a computer.

I've tried unplugging the graphics card and replugging that in?

Any ideas.....please!!!!!! :(

[Sylvander]

Did you perhaps plug the USB plug into the socket the wrong way round?
When I did that once, there was a click and the PC powered off.
I assume I'd caused a short circuit [which would cause a power surge].
In my case I removed the USB plug and put it in the right way around and restarted the PC and all was well.
Perhaps your PC has a protective system that doesn't power off the PC, but just warns the user of the power surge.

Have you removed your Mobile Phone USB plug?
Do it if you have not already done so.
At the moment your PC is failing to complete the BIOS's POST; indeed it may not be getting that far and the POST may not even be starting.
Do you see any signs of the POST in operation?
Any LED's blinking on the optical drives, keyboard, HDD?
The video card is only enabled Late in the POST sequence about the time you hear the single short beep.
Does your beep normally come shortly before or after the first video display image is seen?
Now you get neither of those huh?

Sylvander’s Diagnostic Flowcharts
Download a copy of my diagnostic flowcharts from here
www.erniek.eclipse.co.uk/downloads/sylvanderdiags.zip
and print them to leaf through.
Begin on the STARTUP chart.
-----------------------------------------------
NO POST, NO BEEP, NO VIDEO
www.pcguide.com/vb/showthread.php?t=39685
-----------------------------------------------
If you startup with no RAM in place and get warning beeps, then you know that at least the POST is running and testing and warning [a good sign].

[Sylvander]

Post #2 answer by Ski HERE (http://www.pcguide.com/vb/showthread.php?t=46957) gives a very complete sequence of procedures to test a PC that won't display.

You may decide not to go so far at this stage, but hold that in reserve for when or if simpler measures fail.

[harvest1]

Thanks for the response.

I've unplugged the USB mobile cable. I've even unplugged the front USB lead from the motherboard.
There are no beeps at all. Literally, the fans start and that's it. I am able to eject the CD tray.
It's as if the computer has detected the surge and tried to protect itself. Is there a fuse or something on Motherboards that need switching back/resetting.

That link to the process map is quite useful. Will have a look at that!

:)

[Sylvander]

"Is there a fuse or something on Motherboards"
There is a fuse in the PSU I've heard, but if that had gone the PC would appear "dead".

"That link to the process map is quite useful"
If you begin on the START UP chart, the PC isn't "dead", you're not sure if the POST runs, there are no beeps, so you go to the NO POST chart.
At the NO POST chart you really aught to check that the PSU output is ok, or swap in a known good PSU [a new one?]
Although you could assume it to be ok and disconnect all non-essential items for a bare-bones boot.
This reduces the number of possible culprits to a minimum.
If you still get no completion of the POST you might try a startup with no RAM to see if the POST gives warning beeps [therefore is running although not completing].
Which would you rather do first?
Test the PSU voltages or strip back the hardware to bare-bones?
I can supply instructions for testing the PSU.

"There are no beeps at all"
Which means...
1. Either the POST isn't running, or...
2. The POST begins, but is halted part way through by a failure that the POST isn't designed to give beeps about. Removing the RAM [if the RAM test comes before that point] would result in warning beeps, which would tell you the POST is indeed running.

"the fans start and that's it"
Does the CPU fan run?

[mjc]

It's as if the computer has detected the surge and tried to protect itself. Is there a fuse or something on Motherboards that need switching back/resetting.


No, but there is one or more fuses in the power supply, and yes a power supply can partially work. Remember it supplies several different voltages and drives use the 5 and 12v rails...one of the others could be blown and you could still get fans/drives.

[harvest1]

No, but there is one or more fuses in the power supply, and yes a power supply can partially work. Remember it supplies several different voltages and drives use the 5 and 12v rails...one of the others could be blown and you could still get fans/drives.

Are they standard 5a/3a fuses that you find in plugs? Is is the same process to replace a fuse in the PSU as it is in a plug?

Thanks

[saphalline]

PSU's aren't meant for user servicability. If any part of the PSU dies, it's much better/safer (for those inexperienced in electrical modification) to just buy a new PSU. Many times, simply opening the PSU voids the warranty, so keep that in mind.

To test your PSU, you can try it in another computer or buy a PSU tester for $10-20 at any local computer store/shop.

At this point it doesn't look good. How were your USB ports on the front of your case designed? Was the cable terminated as one solid plug that fit on the mobo's USB header, or were the wires individually set with plugs?

[harvest1]

They all went to one plug on the motherboard!

[harvest1]

No luck with resetting the bios. I've taken the CMOS battery out for 20 mins and replaced, and also tried bridging the reset pins - with no effect.

What I find strange, is before I turned it off everything was fine except for the USB mouse (and presumably all other USB devices). Why when shutting down and rebooting does the PC then do this. I could understand if the screen had gone blank when I originally did this!!!


All the capacitors are fine. I've tried unplugging everything except RAM, CPU, FAN and still nothing.

I'm hoping it's the motherboard and not the CPU, as that's the cheaper option.

Any help would be appreciated!! Thanks

[saphalline]

Have you tried testing the PSU yet?