Help - dead computer (A7V133)

  • Thread starter Thread starter John
  • Start date Start date
J

John

The power went out at my house last night and when it came back on my
computer was dead. I was using a name-brand surge supressor but it
looks like it didn't do what it was supposed to do. Pushing the
computer's power and/or reset buttons yields nothing - the machine
doesn't POST, the hard drive and fans don't start - no activity
whatsoever.

My system has an Asus A7V133 board with an Athlon 1.2GHz processor.
The motherboard must still be getting power because the green LED on
the board will still light up when the machine is plugged in. Other
than being able to conclude that my power supply is probably still
okay I have no idea how to begin troubleshooting this. Where do I
start?


If there was a previous thread that escaped my search and answers this
question please point me to it.

Thanks
 
Strange enough a computer I have with the same motherboard and processor
shows the same behaviour after I came back from a 3 week vacation the
day before yesterday, never had a problem before.
 
The power went out at my house last night and when it came back on my
computer was dead. I was using a name-brand surge supressor but it
looks like it didn't do what it was supposed to do. Pushing the
computer's power and/or reset buttons yields nothing - the machine
doesn't POST, the hard drive and fans don't start - no activity
whatsoever.

My system has an Asus A7V133 board with an Athlon 1.2GHz processor.
The motherboard must still be getting power because the green LED on
the board will still light up when the machine is plugged in. Other
than being able to conclude that my power supply is probably still
okay I have no idea how to begin troubleshooting this. Where do I
start?


If there was a previous thread that escaped my search and answers this
question please point me to it.

Thanks
Click to expand...

It could still be the power supply and/or the motherboard. The power
supply has two independent sections, one supplies the green LED, the
more powerful section supplies the rest of the voltages. Since the
power supply takes the abuse first, I would try another power supply.
If you are still stuck with just the green LED, next you'll need
to RMA the motherboard (or this could be an opportunity to upgrade
to a newer board). But start with the PS first.

If you have a multimeter, you can pull the PS and short PS_ON# to GND
(COM) to switch on the supply. You have to maintain this connection
for as long as you want to test the supply. Then, use your multimeter
to check for voltages on the rest of the supply pins. Without a load
connected, some of the voltages could be higher than normal, so
if you don't have some test loads, the voltage measured alone doesn't
guarantee you've detected a failure. (I use a collection of power
resistors to draw 1 amp or less from each rail.)

http://www.formfactors.org/developer/specs/atx/atx2_1.pdf (pg.19)

If you don't have a multimeter, you can listen for the fan to
start spinning (it should run off +12V inside the PS). If the PS can
be started this way (PS_ON# shorted to COM), then that would lend
more credit to the "dead motherboard" theory.

HTH,
Paul
 
Very quietly manufacturer forget to mention the one type of
surge that expensive product does not protect from. 'Whole
house' type protector connected less than 10 feet to single
point ground was required to protect from the rare and so
destructive surge type. A protector that typically costs
about $1 per protected appliance. Unfortunately, those
expensive plug-in protectors don't even claim protection from
that type of surge. So instead they forget to mention which
surge they protect from - so that you will assume it protects
from all types of surges.

However now that damage exists, repair starts with a 3.5
digit multimeter. Don't remove or replace anything. First
collect basic facts. What is voltage on purple wire that
connects power supply to motherboard - with only power cord
plugged in and no attempt to turn computer on? That is the
first measurement. Should be about 5 volts.

Then voltage on green wire is verified for response to a
pressed power switch. Above 2 volts when power supply should
be off. Less than 0.7 volts when power supply should be turned
on.

If these voltages exist, then monitor each voltage as power
supply is turned on, as listed in chart at:
http://www.hardwaresite.net/faqpowersupply.html

Most important is reaction monitored on yellow, red, and
orange wires.

Based upon numbers learned here, only then are we ready to
plan the next step.
 
BTW, with too much voltage cycling, control circuits can
lock out the power supply. This lockout is removed by
unplugging computer, waiting a few seconds, then restoring
power cord.

Others dealing with similar problem are in the newsgroup
alt.comp.hardware.pc-homebuilt entitled "Do you think my PSU
is powerful enough?" starting 13 Oct 2003 and in the
newsgroup alt.sys.pc-clone.gateway2000 entitled
"How do you test a power supply?" on 10 Oct 2003.
 
Thanks for the advice, it was the power supply.

I swapped it out for another one I have and everything works fine.

Now I need to try to get Belkin to replace my very expensive and very
dead ProSilence PSU. I suspect they'll have some way of avoiding any
responsibility. If anyone has experience in dealing with this type of
situation I'm open for suggestions.

Thanks
 
Back
Top