Power Supply compatibility?

[My father's son]

I had a Soyo computer which didn't work: All it did was turn on, light up a
few lights on the CD-ROM, start the fan whirring and I got some very minor
clicking. Nothing whatsoever got transmitted from the computer to the
monitor which would stop the light on the monitor from flashing as if there
was nothing connected

Soyo eventually told me that the mobo was probably at fault so I replaced it
with an Asus P3V133 which I am now using with the 450 Mhz Pentium 11.

Which (when I THINK I got all the processor and voltages/bus speeds and
multiples correct) does exactly the same thing

So I am wondering if it might actually be a problem with the power supply,
a problem Soyo didn't consider.

So I bought a Compaq one for a munificent $3 at a local flea market.

Does anyone know if all ATX power supplies will work with Asus mobos? I
found out (not the hard way) that apparently all Dell ones are different and
if you plug a Dell one into a non-Dell mobo, it may welll fry the circuits.
Unlike the original Soyo power supply the Compaq doesnt have a power switch
on it and when I tried testing the voltages to see if they went with the
voltages cleverly set out on the manual, nothing is measures apparently
unless you plug it in to place a load on it (the fan doesnt even go on when
you plug the power supply into the mains)

"Brothers and Sisters Have I None
But That Man's Father is My Father's Son"

 

[DaveW]

If you're willing to risk all your computer hardware on a $3 non-standard
Compaq power supply, I wish you much luck...

 

[My father's son]

I think there may be some possibility that you might just conceivably have
missed the point of my message somewhat completely? What I was asking was
whether anyone knew whether it IS a standard power supply? (Not whether
there was any risk if it isn't)

 

[Paul]

I think there may be some possibility that you might just conceivably have
missed the point of my message somewhat completely? What I was asking was
whether anyone knew whether it IS a standard power supply? (Not whether
there was any risk if it isn't)

You can find the pinout for a 20 pin ATX power connector on page 19 of:
http://www.formfactors.org/developer/specs/atx/atx2_1.pdf

To start an ATX supply, switch on the switch on the back of the unit.
Then, connector PS_ON# to one of the COM pins. You should hear and
see the PS fan start to spin. Now, grab your voltmeter and probe
the supply pins with respect to another one of the COM pins. You should
see voltages in the ballpark of the stated values.

If instead, you got an AT supply, I think the supply runs as soon as
the supply is switched on. There is no PS_ON# on an AT supply. I think
there are also two separate groups of wires for the motherboard power.
Based on that, you may be able to determine whether you bought an
AT or an ATX supply. (The P3V133 looks like it has an ATX connector in
the manual I downloaded.)

About the only other issue would be the capacity of the supply. Each output
of the supply has a current limit as to how much it will provide. It
is pretty hard to calculate how much a motherboard will need, because
hardly any manufacturers list power consumption for hardware. The label
on the supply may indicate the limits on each of the rails. Older
motherboards tend to draw most of their power from +3.3V and +5V, while
new boards use more +12V. A guess would be that the board draws somewhere
around 120W total, and a 250W supply or higher might be enough to do the
job - just be aware that the real determinant is the rating of the
individual supply outputs. Sorry I cannot be more precise than that.

Also, be careful while working on the PS. If you short an output, many
amps can flow and stuff can get hot (wires, PS, whatever). Not all PS
are equally well designed - it is amazing how many supplies don't
have overcurrent and overvoltage protection.

Good luck,
Paul

 

[Gary Tait]

I had a Soyo computer which didn't work: All it did was turn on, light up a
few lights on the CD-ROM, start the fan whirring and I got some very minor
clicking. Nothing whatsoever got transmitted from the computer to the
monitor which would stop the light on the monitor from flashing as if there
was nothing connected

Soyo eventually told me that the mobo was probably at fault so I replaced it
with an Asus P3V133 which I am now using with the 450 Mhz Pentium 11.

Which (when I THINK I got all the processor and voltages/bus speeds and
multiples correct) does exactly the same thing

So I am wondering if it might actually be a problem with the power supply,
a problem Soyo didn't consider.

So I bought a Compaq one for a munificent $3 at a local flea market.

Does anyone know if all ATX power supplies will work with Asus mobos? I
found out (not the hard way) that apparently all Dell ones are different and
if you plug a Dell one into a non-Dell mobo, it may welll fry the circuits.
Unlike the original Soyo power supply the Compaq doesnt have a power switch
on it and when I tried testing the voltages to see if they went with the
voltages cleverly set out on the manual, nothing is measures apparently
unless you plug it in to place a load on it (the fan doesnt even go on when
you plug the power supply into the mains)

"Brothers and Sisters Have I None
But That Man's Father is My Father's Son"

Buy a real clone supply, not one from an OEM.