HP power supply and PC shutting off

  • Thread starter Thread starter NuQ
  • Start date Start date
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NuQ

Friend brought me her HP desktop, don't have the model in front of me
now, but it's a 2.0 GHz P4.

It keeps powering off, not Windows shutdown, but just cuts right off.
The first thing I thought of was heat, so I blew it out, although it
wasn't terribly dusty. Seen much much worse. That didn't help. NExt
thing I thought was virus or spyware, but it came up clean. Next thing
I tried was booting into safe mode and leaving it. Seemed to stay up
longer, a couple of hours as opposed to 10 - 40 mins in normal mode.

So, I thought maybe it IS a hardware issue. I tried a known working
Antec 400W that I had, but it doesn't power on at all. And yes, I
connected the main power and the 4 pin power, but had it laying on the
desk. Tried resting on the case thinking it may need to be grounding to
case of something.

Any advise in this area would be appreciated. I don't have a volt meter
to take readings, but maybe it's time I invest in one.
 
NuQ said:
Friend brought me her HP desktop, don't have the model in front of me
now, but it's a 2.0 GHz P4.

It keeps powering off, not Windows shutdown, but just cuts right off.
The first thing I thought of was heat, so I blew it out, although it
wasn't terribly dusty. Seen much much worse. That didn't help. NExt
thing I thought was virus or spyware, but it came up clean. Next thing
I tried was booting into safe mode and leaving it. Seemed to stay up
longer, a couple of hours as opposed to 10 - 40 mins in normal mode.

So, I thought maybe it IS a hardware issue. I tried a known working
Antec 400W that I had, but it doesn't power on at all. And yes, I
connected the main power and the 4 pin power, but had it laying on the
desk. Tried resting on the case thinking it may need to be grounding to
case of something.

Any advise in this area would be appreciated. I don't have a volt meter
to take readings, but maybe it's time I invest in one.
Click to expand...

An overheating CPU perhaps ? P4's are equipped with THERMTRIP, which
will shut off the power. Check that the heatsink is making good contact.
Or find a utility that can report the CPU temp, to give some idea
whether that is the problem or not.

Paul
 
Paul said:
An overheating CPU perhaps ? P4's are equipped with THERMTRIP, which
will shut off the power. Check that the heatsink is making good contact.
Or find a utility that can report the CPU temp, to give some idea
whether that is the problem or not.

Paul
Click to expand...

Good thought and should have mentioned that. I did install Everest Home
Edition which gave a CPU temp of around 38 celsius and I'm sssuming that
the reading is accurate, but it may very well not be. Your right, it
might be a good idea to remove the heatsink, clean it and apply some
thermal compound anyway. Thanks for the suggestion!
 
NuQ said:
Good thought and should have mentioned that. I did install Everest Home
Edition which gave a CPU temp of around 38 celsius and I'm sssuming that
the reading is accurate, but it may very well not be. Your right, it
might be a good idea to remove the heatsink, clean it and apply some
thermal compound anyway. Thanks for the suggestion!
Click to expand...


Is the HP supply an ATX type ? Maybe the reason the Antec didn't work,
is a difference in pinout. At the very least, compare the wire harness
colors, and see if they are the same. Since your CPU seems decently
cool, it could be the original PSU which has become weak. PSUs are
one of the most common failure types.

Paul
 
Paul said:
Is the HP supply an ATX type ? Maybe the reason the Antec didn't work,
is a difference in pinout. At the very least, compare the wire harness
colors, and see if they are the same. Since your CPU seems decently
cool, it could be the original PSU which has become weak. PSUs are
one of the most common failure types.
Click to expand...

It is an ATX, it even says it on the sticker. I just noticed that the
PS fan stays on even after the PC is shut off. I have to press and hold
in the power button so that it completely powers down before I can power
it back on.

Seems really strange and seems like it could be a Windows problem. What
do you think?
 
Paul said:
Is the HP supply an ATX type ? Maybe the reason the Antec didn't work,
is a difference in pinout. At the very least, compare the wire harness
colors, and see if they are the same. Since your CPU seems decently
cool, it could be the original PSU which has become weak. PSUs are
one of the most common failure types.

Paul
Click to expand...

Well, I found out it's not a Windows problem. I remembered I had a
Ubuntu Linux disc that I could boot off of and run live. About 4 mins
into booting from the CD it powering off.

Since I'm home now, it's a HP Pavilion 533w with a 2.0 Celeron (thought
it was P4). The PS is smaller than the Antec I tried, the Antec
wouldn't fit in the case, but it still seems like it should POST with it.

Does HP use some odd power supplies or something?
 
NuQ said:
Well, I found out it's not a Windows problem. I remembered I had a
Ubuntu Linux disc that I could boot off of and run live. About 4 mins
into booting from the CD it powering off.

Since I'm home now, it's a HP Pavilion 533w with a 2.0 Celeron (thought
it was P4). The PS is smaller than the Antec I tried, the Antec
wouldn't fit in the case, but it still seems like it should POST with it.

Does HP use some odd power supplies or something?
Click to expand...

That is why I suggested checking the wire harness colors. Just to see if
there are any significant differences. Maybe the Antec is missing -5V,
although there is no good reason for a motherboard to depend on the -5V
supply. It has been obsolete for some time.

To start a power supply (like the Antec), the motherboard has to be
able to pull the PS_ON# logic signal low (near zero volts). The signal
is open collector, meaning a resistor pulls the signal towards +5VSB,
and the motherboard is supposed to sink the current from that resistor,
and send a low level to the power supply. That is supposed to turn it
on. If your motherboard was sitting in front of me, I'd connect my
multimeter, and verify that with the Antec connected, I have a hot
+5VSB rail, from PSU to motherboard, and the PS_ON# changes from
5V to near 0V, when the front panel switch is pushed.

If, for any reason, the motherboard cannot maintain a 0 volt level on
the PS_ON# signal, and the signal goes back to 5V, then that'll
shut things off.

Paul
 
Paul said:
That is why I suggested checking the wire harness colors. Just to see if
there are any significant differences. Maybe the Antec is missing -5V,
although there is no good reason for a motherboard to depend on the -5V
supply. It has been obsolete for some time.

To start a power supply (like the Antec), the motherboard has to be
able to pull the PS_ON# logic signal low (near zero volts). The signal
is open collector, meaning a resistor pulls the signal towards +5VSB,
and the motherboard is supposed to sink the current from that resistor,
and send a low level to the power supply. That is supposed to turn it
on. If your motherboard was sitting in front of me, I'd connect my
multimeter, and verify that with the Antec connected, I have a hot
+5VSB rail, from PSU to motherboard, and the PS_ON# changes from
5V to near 0V, when the front panel switch is pushed.

If, for any reason, the motherboard cannot maintain a 0 volt level on
the PS_ON# signal, and the signal goes back to 5V, then that'll
shut things off.
Click to expand...

Ok, I compared the wires and there is a difference besides just the
colors. There are two wires going into one pin at the end of the HP PS
that plugs into the motherboard. You know what I mean? There are 20
pins and 20 wires, but one pin is empty and one pin has two wires. On
the Antec there is just one wire in each of the 20 pins.
 
NuQ said:
Ok, I compared the wires and there is a difference besides just the
colors. There are two wires going into one pin at the end of the HP
PS that plugs into the motherboard. You know what I mean? There are
20 pins and 20 wires, but one pin is empty and one pin has two wires.
On the Antec there is just one wire in each of the 20 pins.
Click to expand...

What is the color of those two wires, and which pins are involved ?
 
NuQ said:
Well, I found out it's not a Windows problem. I remembered I had a
Ubuntu Linux disc that I could boot off of and run live. About 4 mins
into booting from the CD it powering off.

Since I'm home now, it's a HP Pavilion 533w with a 2.0 Celeron (thought
it was P4). The PS is smaller than the Antec I tried, the Antec
wouldn't fit in the case, but it still seems like it should POST with it.

Does HP use some odd power supplies or something?
Click to expand...

Often, they're an odd size/shape. But Standard ATX pins. Your antec
ought to work for troubleshooting, at least.
 
NuQ said:
Ok, I compared the wires and there is a difference besides just the
colors. There are two wires going into one pin at the end of the HP PS
that plugs into the motherboard. You know what I mean? There are 20
pins and 20 wires, but one pin is empty and one pin has two wires. On
the Antec there is just one wire in each of the 20 pins.
Click to expand...

Why you didn't think to mention the color of the wire with two wires
going into one pin is beyond me. Chances are it is the 3.3v, and the
extra wire is a voltage sense wire. Likely not your problem, anyway.

What pin numbers had different color of wires? HP *has* used some
proprietary PSUs in the past, but I thought they stopped. If not, the
PS_ON wire is not standard in the regular place, so the standard PSU
won't even turn on.
 
Rod said:
What is the color of those two wires, and which pins are involved ?
Click to expand...

The two wires are orange and light brown or tan. It is the last (or
first) pin, it's on the every end. The missing pin is on the opposite
side third from the end.
 
Often, they're an odd size/shape. But Standard ATX pins. Your antec
ought to work for troubleshooting, at least.
Click to expand...

I just realized it's a micro ATX PS, not a full sized ATX.
 
UCLAN said:
Why you didn't think to mention the color of the wire with two wires
going into one pin is beyond me.
Click to expand...


Cause I'm a knucklehead!

Chances are it is the 3.3v, and the
extra wire is a voltage sense wire. Likely not your problem, anyway.

What pin numbers had different color of wires? HP *has* used some
proprietary PSUs in the past, but I thought they stopped. If not, the
PS_ON wire is not standard in the regular place, so the standard PSU
won't even turn on.
Click to expand...

There were too many different ones. Some colors are in different places
and some colors are not common between them.
 
The two wires are orange
Click to expand...

Thats a 3.3V
and light brown or tan.
Click to expand...

That's remote sense for the 3.3V, so the power supply can regulate that at
the connector itself, rather than at the power supply end of the orange wire.
It is the last (or first) pin, it's on the every end.
Click to expand...

First, pin 1.
The missing pin is on the opposite side third from the end.
Click to expand...

Pin 18, -5V which isnt used anymore.

http://www.technick.net/public/code/cp_dpage.php?aiocp_dp=pinconmth_atx_power

Odd that the Antec didnt work, it should have.
 
NuQ said:
Cause I'm a knucklehead!

Chances are it is the 3.3v, and the

There were too many different ones. Some colors are in different
places and some colors are not common between them.
Click to expand...

That certainly explains why the Antec didnt work.
 
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