Dead: Motherboard or CPU?

  • Thread starter Thread starter donotemailme
  • Start date Start date
D

donotemailme

My machine crashed, and now when I press the power button nothing
happens - no BIOS screen, no LEDs, no fans. I tried a new power supply,
same result. I tried a different power switch, same result.

The motherboard is an ARIMA HDAMB.

I noticed that if I plug the 24pin power supply connector into the m/b
first, all the fans start running. When I plug the 8pin connector into
the m/b, all the fans stop and nothing happens when I press the power
button. I saw in the ARIMA manual that the 8pin connector is dedicated
for the CPUs. Do you suspect that the m/b has failed or one of the
CPUs?

Thanks for your input.
 
Thanks WebWalker. That makes a difference, but it doesn't fix the
problem. Now, when I hit the power button the drive (HDD, DVD-ROM,
Floppy) LEDs light up, the fans all kick on, after a second or two the
drive LEDs turn off, but nothing else happens. No video (the card is
fine, and I tried a PCI card in there too in case the AGP slot was
bad), pressing num-lock doesn't turn the num-lock LED on, and the power
LED *never* comes on.

I should have also mentioned, when I first plug the power supply into
the motherboard, I get a quick whiff of an electrical burning smell.
It goes away pretty quickly and I don't see any smoke.
 
Thanks WebWalker. That makes a difference, but it doesn't fix the
problem. Now, when I hit the power button the drive (HDD, DVD-ROM,
Floppy) LEDs light up, the fans all kick on, after a second or two the
drive LEDs turn off, but nothing else happens. No video (the card is
fine, and I tried a PCI card in there too in case the AGP slot was
bad), pressing num-lock doesn't turn the num-lock LED on, and the power
LED *never* comes on.

I should have also mentioned, when I first plug the power supply into
the motherboard, I get a quick whiff of an electrical burning smell.
It goes away pretty quickly and I don't see any smoke.
Click to expand...

Sounds like you have a bad cap on the motherboard.
 
Your are doing what bad technicians so often recommend -
shotgunning. Do as engineers have done for generations.
Newer unplug or disconnect anything to find the failed item up
front. It requires a 3.5 digit multimeter that is so
ubiquitous as to be sold even in Home Depot, Lowes, Radio
Shack and Sears. In your case, voltage on the purple, green,
and gray wires should have special attention before, during,
and after the switch is pressed. Previous text that provides
the underlying concepts and procedures for verifying the power
supply 'system' (yes the system is more than just a power
supply) are discussed in:
"Computer doesnt start at all" in alt.comp.hardware on 10
Jan 2004 at
http://tinyurl.com/2t69q and
"I think my power supply is dead" in alt.comp.hardware on 5
Feb 2004 at
http://www.tinyurl.com/2musa

Now for something that bothers me in you post. Did you make
or break any connections when the power cord was plugged into
the wall? No just powered off. Computer must be completely
disconnected from the wall receptacle so that damage does not
get created when disconnecting power supply 24 pin connector
from other parts of the power supply 'system'.

If you collect the numbers and still don't understand what
you have, well, now you have something to post that will
attract the more knowledgeable. Currently your post about
fans spinning when you first make a connection tells us
nothing useful. And you have not provided enough information
to even suspect fails capacitors. Get the meter, get the
numbers, and identify the failed part up front without even
replacing the power switch on a whim.
 
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