a7v600 burns out power suppliers ?

  • Thread starter Thread starter Max
  • Start date Start date
M

Max

Hi, does anyone who owns the mb
had power supply burns out ?

That did happens to a 350W,
I replaced with a 400, there
was nothing on the pc but
a videocard, and a hard disk,
what happened ?

The only strange thing that I noticed
was a raising +12V level, alarmed.

I did raised the limit, then it shuts down
and never started again until I replaced
the power supply. Will it happen again ?

that's the mother board or a defective power supply ?

cheers
Max
 
"Max" said:
Hi, does anyone who owns the mb
had power supply burns out ?

That did happens to a 350W,
I replaced with a 400, there
was nothing on the pc but
a videocard, and a hard disk,
what happened ?

The only strange thing that I noticed
was a raising +12V level, alarmed.

I did raised the limit, then it shuts down
and never started again until I replaced
the power supply. Will it happen again ?

that's the mother board or a defective power supply ?

cheers
Max
Click to expand...

A lot of PC power supplies use one primary circuit to
drive the multiple secondary circuits. If one of the
outputs becomes heavily loaded, feedback from secondary
to primary asks the supply to increase all the outputs.

Say there are the three outputs +3.3V, +5V, +12V.
If you find two of them are abnormally high in voltage,
then the third voltage is the one being shorted, and the
supply tries to increase all the outputs, to compensate
for the load.

First of all, go to the monitor page in the BIOS and write
down the voltage readings. Then, remove the motherboard
from the case and assembly a minimum system while the
motherboard rests on an insulator, like a piece of
cardboard. If you find the voltage readings in the monitor
have returned to more normal values, then the short must
have been to the bottom of the board. Remove any standoffs
on the motherboard tray that don't align with a plated
hole in the motherboard.

Occasionally, something will short on or inside the
motherboard itself. Someone on the Abit group, posted a
link to a picture of a motherboard that burned up. All
of the area around the processor was blackened by the
large currents drawn by a short in the processor area.

I would not install a third power supply, and would RMA
the motherboard if the warranty is still valid. The
motherboard will just keep damaging power supplies or
end up burning.

It would be a relatively simple matter for a service
person to determine which power rail is being shorted,
but it is damn tough to find the part on the board doing
the shorting. I've tried looking before, in a lab
enironment, for heat or magnetic field, and some shorts
(power planes) are just impossible to find. If the short
is inside the motherboard (i.e. on one of the internal
copper layers of the four layer board), it cannot be fixed
anyway, and Asus would have to discard the RMA'ed board.

Good luck,
Paul
 
Paul said:
A lot of PC power supplies use one primary circuit to
drive the multiple secondary circuits. If one of the
outputs becomes heavily loaded, feedback from secondary
to primary asks the supply to increase all the outputs.

Say there are the three outputs +3.3V, +5V, +12V.
If you find two of them are abnormally high in voltage,
then the third voltage is the one being shorted, and the
supply tries to increase all the outputs, to compensate
for the load.

First of all, go to the monitor page in the BIOS and write
down the voltage readings. Then, remove the motherboard
from the case and assembly a minimum system while the
motherboard rests on an insulator, like a piece of
cardboard. If you find the voltage readings in the monitor
have returned to more normal values, then the short must
have been to the bottom of the board. Remove any standoffs
on the motherboard tray that don't align with a plated
hole in the motherboard.

Occasionally, something will short on or inside the
motherboard itself. Someone on the Abit group, posted a
link to a picture of a motherboard that burned up. All
of the area around the processor was blackened by the
large currents drawn by a short in the processor area.

I would not install a third power supply, and would RMA
the motherboard if the warranty is still valid. The
motherboard will just keep damaging power supplies or
end up burning.

It would be a relatively simple matter for a service
person to determine which power rail is being shorted,
but it is damn tough to find the part on the board doing
the shorting. I've tried looking before, in a lab
enironment, for heat or magnetic field, and some shorts
(power planes) are just impossible to find. If the short
is inside the motherboard (i.e. on one of the internal
copper layers of the four layer board), it cannot be fixed
anyway, and Asus would have to discard the RMA'ed board.

Good luck,
Paul
Click to expand...

I cant see it being a short on the board. He is able to star the pc and
monitor the voltages, if the short was there then this should cause the psu
to shut down (or burn out) faster than it would take him to load the bios
and navigate to the monitor screen. Not saying it's not possible however,
just that I wouldnt put my bets on it being a short :).
 
"rstlne" said:
I cant see it being a short on the board. He is able to star the pc and
monitor the voltages, if the short was there then this should cause the psu
to shut down (or burn out) faster than it would take him to load the bios
and navigate to the monitor screen. Not saying it's not possible however,
just that I wouldnt put my bets on it being a short :).
Click to expand...

He has noted one of his output voltages is high, and that
means the power supply is working hard right now, fighting
the overload on another output. Since he has the experience
with two PS, the motherboard is doing it. (The combination
of a high output rail voltage, plus the fact he's burned out
a PS already, is how I reach this conclusion. Either symptom
by itself would not be enough to reach a conclusion.)

Sometimes you get lucky, and by feeling around the system
with your hand, or using your nose, you can locate the part
of the system that is in overload. But it doesn't work that
way all the time.

HTH,
Paul
 
Paul said:
He has noted one of his output voltages is high, and that
means the power supply is working hard right now, fighting
the overload on another output. Since he has the experience
with two PS, the motherboard is doing it. (The combination
of a high output rail voltage, plus the fact he's burned out
a PS already, is how I reach this conclusion. Either symptom
by itself would not be enough to reach a conclusion.)

Sometimes you get lucky, and by feeling around the system
with your hand, or using your nose, you can locate the part
of the system that is in overload. But it doesn't work that
way all the time.
Click to expand...

Thanks for your answers, gentlemen.

Does the fact that the power supply smell of barbecue rightnow
(rightnow I mean nowadays with the new PS, because I barely use
this pc) sounds in the direction all this is happening right now ?

The moment the first PS died, it becan to beep to warn for an
increase, this one isn't yet, but I will wait no more to test isolation.

And if it is the mother board, well, I will rma'it very fast

thanks again and wish you the best

Max
 
I've got a 2600+ with 4 drives and a video board on an A7V600 hooked up to
an antec 300 watt PS. THe voltage readings according to the ASUS utilites
are just about dead on what they should be. Its only been up two weeks but
so far nothing untoward from the PS as far as I can tell.
 
I cant see it being a short on the board. He is able to star the pc and
monitor the voltages, if the short was there then this should cause the psu
to shut down (or burn out) faster than it would take him to load the bios
and navigate to the monitor screen. Not saying it's not possible however,
just that I wouldnt put my bets on it being a short :).
Click to expand...

I guess this is a small terminology problem. I use the word "short",
because everyone will understand that to mean an "unintended ohmic
path". If the ohms from such a path are high, the PS will hardly
even notice the extra load. As the quality of the ohmic path improves,
the supply will be driven to its rated load, and the air coming out
of the PS will be hot. Since the current limits on some supplies
are set really high (to prevent accidental shutdowns, when running
at exactly the rated output), with the right value of unintended
ohmic path, you can cook a supply, without the protection being
triggered.

One poster here who had a power problem, claimed he couldn't touch
the metal on the back of his PS. That means the case temp of the
PS was over 50C, and yet the power supply was still running. I
wouldn't expect a supply running with that kind of overload, to
live too long.

With the current output capabilities of ATX PS, just about any
"short" is a "partial short", and the PS keeps on grunting.

Paul
 
Paul said:
He has noted one of his output voltages is high, and that
means the power supply is working hard right now, fighting
the overload on another output. Since he has the experience
with two PS, the motherboard is doing it. (The combination
of a high output rail voltage, plus the fact he's burned out
a PS already, is how I reach this conclusion. Either symptom
by itself would not be enough to reach a conclusion.)

Sometimes you get lucky, and by feeling around the system
with your hand, or using your nose, you can locate the part
of the system that is in overload. But it doesn't work that
way all the time.
Click to expand...

I did unplug the mobo and plug it again, what comes out from the
voltage monitor is that the 12v is slightly high, like 12.8-12.9,
is this normal ? with this new power supply this is stable.

the feeling I had with the former was that it was rising up to
a not reliable level, and then it stops to what I tought was
a normal precautional shutdown.
 
Back
Top