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Possibly Dead P4S8X?



 
 
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  #1  
Old August 14th 04, 02:01 PM
JPeterman
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Posts: n/a
Default Possibly Dead P4S8X?

After returning from a camping trip I hit the power button on my
computer.

The red light on the front came on but no display. I noticed that the
red light is burning solid. I took the cover off the computer and made
sure connections were tight. When I power it up a red light on the
motherboard flashes once. There is a green light on the motherboard
that stays lit. However the onboard fan does not start. The fan on the
computer case does work.

The last time I used the computer (yesterday) everything was running
fine.

The computer has a 2.8GhZ P-IV with WinXP Pro
512 MB DDR
120 MB Maxtor 7200 rpm HDD
40 MB Maxtor 7200 rpm HDD
Pioneer DVDROM
Pioneer DVD-Writer

The computer is only about 1.5 years old.

Any ideas? Thank you.
  #2  
Old August 15th 04, 12:23 AM
DaveW
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Posts: n/a
Default

It sounds like either the power supply unit or the motherboard failed. The
easiest way to see is to try replacing the PSU with a known working one of
adequate output.

--
DaveW



"JPeterman" biteme@thelibrary wrote in message
...
After returning from a camping trip I hit the power button on my
computer.

The red light on the front came on but no display. I noticed that the
red light is burning solid. I took the cover off the computer and made
sure connections were tight. When I power it up a red light on the
motherboard flashes once. There is a green light on the motherboard
that stays lit. However the onboard fan does not start. The fan on the
computer case does work.

The last time I used the computer (yesterday) everything was running
fine.

The computer has a 2.8GhZ P-IV with WinXP Pro
512 MB DDR
120 MB Maxtor 7200 rpm HDD
40 MB Maxtor 7200 rpm HDD
Pioneer DVDROM
Pioneer DVD-Writer

The computer is only about 1.5 years old.

Any ideas? Thank you.



  #3  
Old August 15th 04, 12:55 AM
Paul
external usenet poster
 
Posts: n/a
Default

In article , awtwtw wrote:

After returning from a camping trip I hit the power button on my
computer.

The red light on the front came on but no display. I noticed that the
red light is burning solid. I took the cover off the computer and made
sure connections were tight. When I power it up a red light on the
motherboard flashes once. There is a green light on the motherboard
that stays lit. However the onboard fan does not start. The fan on the
computer case does work.

The last time I used the computer (yesterday) everything was running
fine.

The computer has a 2.8GhZ P-IV with WinXP Pro
512 MB DDR
120 MB Maxtor 7200 rpm HDD
40 MB Maxtor 7200 rpm HDD
Pioneer DVDROM
Pioneer DVD-Writer

The computer is only about 1.5 years old.

Any ideas? Thank you.


As Dave said, the power supply is always a likely source of
failure to boot.

But, one of your other symptoms bothers me a bit. The red LED
on the motherboard is the "AGP_Warn" circuit. It is supposed
to check for an illegal 3.3V only video card, and prevent the
computer from starting. If an illegal (improperly keyed) video
card is present, the PS_ON# signal is prevented from reaching
the power supply, by AGP_Warn.

The AGP_Warn has two ingredients. One I have traced down, so
I know it is there. The TYPEDET# signal from pin A2 on the
video card is connected to one of the transistors. Apparently,
if TYPEDET# is grounded, everything is OK. If TYPEDET# floats,
then that will cause the red LED to light up.

A second ingredient of the check, is the circuit can only
stop the power, if an AGP card is inserted. It would be
inappropriate for the circuit to light the LED, if no video
card is present. So, to do its job, the logic has to be
AGP_Present AND TYPEDET#_floating. I don't know what pin is
checked to verify the card is present.

Now, your symptom of the LED flashing for a moment is weird.
The inputs to AGP_Warn are supposed to be static and unchanging.
Yet, your AGP_Warn lights for a moment and then stops, and
I cannot think of a mechanism for that to happen, unless +5VSB
is going out. And, you said the green LED on the motherboard
stays lit and the fan runs on the back of the case. That means
+5VSB is present and +12V is there to run the fan.

If you have another video card compatible with the board,
try swapping that in. It could be the video card, but as I
say, I cannot really think of a failure mechanism that would
cause the LED to light (indicating trouble) and then
extinguish, unless all power was being lost at the same time.

Paul
  #4  
Old August 15th 04, 02:36 AM
JPeterman
external usenet poster
 
Posts: n/a
Default

On Sat, 14 Aug 2004 23:23:58 GMT, "DaveW" wrote:

It sounds like either the power supply unit or the motherboard failed. The
easiest way to see is to try replacing the PSU with a known working one of
adequate output.


Thank you Dave.

  #5  
Old August 15th 04, 02:52 AM
JPeterman
external usenet poster
 
Posts: n/a
Default

On Sat, 14 Aug 2004 19:55:28 -0400, (Paul) wrote:

In article , awtwtw wrote:



As Dave said, the power supply is always a likely source of
failure to boot.

But, one of your other symptoms bothers me a bit. The red LED
on the motherboard is the "AGP_Warn" circuit. It is supposed
to check for an illegal 3.3V only video card, and prevent the
computer from starting. If an illegal (improperly keyed) video
card is present, the PS_ON# signal is prevented from reaching
the power supply, by AGP_Warn.

The AGP_Warn has two ingredients. One I have traced down, so
I know it is there. The TYPEDET# signal from pin A2 on the
video card is connected to one of the transistors. Apparently,
if TYPEDET# is grounded, everything is OK. If TYPEDET# floats,
then that will cause the red LED to light up.

A second ingredient of the check, is the circuit can only
stop the power, if an AGP card is inserted. It would be
inappropriate for the circuit to light the LED, if no video
card is present. So, to do its job, the logic has to be
AGP_Present AND TYPEDET#_floating. I don't know what pin is
checked to verify the card is present.

Now, your symptom of the LED flashing for a moment is weird.
The inputs to AGP_Warn are supposed to be static and unchanging.
Yet, your AGP_Warn lights for a moment and then stops, and
I cannot think of a mechanism for that to happen, unless +5VSB
is going out. And, you said the green LED on the motherboard
stays lit and the fan runs on the back of the case. That means
+5VSB is present and +12V is there to run the fan.

If you have another video card compatible with the board,
try swapping that in. It could be the video card, but as I
say, I cannot really think of a failure mechanism that would
cause the LED to light (indicating trouble) and then
extinguish, unless all power was being lost at the same time.

Paul


Firstly let me thank you for your detailed response. Most of this was
over my head but I understand the gist of it.

The power button on the front of the case will not turn the power off.
I have to hit the switch on the back.
I just tried it again and the red LED on the motherboard will not
flash at all.

I forgot that there is a voice "post reporter" at boot that may tell
me something. I didn't have the speakers on when this happened so I'm
going to try it.

So the power supply may be suspect even though it powers the other two
fans?
I don't have another video card but I have been leaning towards
getting another one.
Thanks again for your patience and time.


  #6  
Old August 15th 04, 10:57 AM
Paul
external usenet poster
 
Posts: n/a
Default

In article , JPeterman
biteme@thelibrary wrote:

On Sat, 14 Aug 2004 19:55:28 -0400, (Paul) wrote:

In article , awtwtw wrote:



As Dave said, the power supply is always a likely source of
failure to boot.

But, one of your other symptoms bothers me a bit. The red LED
on the motherboard is the "AGP_Warn" circuit. It is supposed
to check for an illegal 3.3V only video card, and prevent the
computer from starting. If an illegal (improperly keyed) video
card is present, the PS_ON# signal is prevented from reaching
the power supply, by AGP_Warn.

The AGP_Warn has two ingredients. One I have traced down, so
I know it is there. The TYPEDET# signal from pin A2 on the
video card is connected to one of the transistors. Apparently,
if TYPEDET# is grounded, everything is OK. If TYPEDET# floats,
then that will cause the red LED to light up.

A second ingredient of the check, is the circuit can only
stop the power, if an AGP card is inserted. It would be
inappropriate for the circuit to light the LED, if no video
card is present. So, to do its job, the logic has to be
AGP_Present AND TYPEDET#_floating. I don't know what pin is
checked to verify the card is present.

Now, your symptom of the LED flashing for a moment is weird.
The inputs to AGP_Warn are supposed to be static and unchanging.
Yet, your AGP_Warn lights for a moment and then stops, and
I cannot think of a mechanism for that to happen, unless +5VSB
is going out. And, you said the green LED on the motherboard
stays lit and the fan runs on the back of the case. That means
+5VSB is present and +12V is there to run the fan.

If you have another video card compatible with the board,
try swapping that in. It could be the video card, but as I
say, I cannot really think of a failure mechanism that would
cause the LED to light (indicating trouble) and then
extinguish, unless all power was being lost at the same time.

Paul


Firstly let me thank you for your detailed response. Most of this was
over my head but I understand the gist of it.

The power button on the front of the case will not turn the power off.
I have to hit the switch on the back.
I just tried it again and the red LED on the motherboard will not
flash at all.

I forgot that there is a voice "post reporter" at boot that may tell
me something. I didn't have the speakers on when this happened so I'm
going to try it.

So the power supply may be suspect even though it powers the other two
fans?
I don't have another video card but I have been leaning towards
getting another one.
Thanks again for your patience and time.


Your observation that the switch on the back is needed for control
changes things a bit.

The PSU has several output voltages. Perhaps only one of them is
not working, and the others are. If you own a voltmeter, you can
take a disk drive power connector in hand, and check for +5V and
+12V. If the PSU has a six pin Aux power connector, there will
be a +3.3V pin on it. Those are the major voltages, and I don't
know if the motherboard depends on -5V and -12V in any meaningful
way or not. On my P4C800-E for example, -12V is used by
the serial port, so if -12V dies, my serial port will die, but
the rest of the board will still run. It could be your PSU has
lost +3.3V or +5V.

When using your voltmeter, connect the black lead to a lug on
one of the connectors on the back of the computer. I'm assuming
you have some alligator clips or another clever way to connect it.
The reason is, you don't want to accidently touch the two voltmeter
leads together while working on the power supply. I find with one
red lead in my hand, things are much safer. It is like safety rules
for jumpering car batteries - there is a lot of available current
there if you make a mistake.

I think as Dave said, I'd try a PSU swap first. If the result is
that the red LED stays on, borrow another video card, to see
if it will go off again. If the red LED stays on even with
another video card, it is time to RMA the motherboard. The
AGP_Warn circuit has failed on some motherboards out of the box,
but I've never heard of one dying on a system that was working
for a while.

Your AGP_Warn is just another mystery for the books :-)
I haven't traced the whole circuit, and as those SMT components
are so hard to identify, I probably never will finish it.

HTH,
Paul
  #7  
Old August 15th 04, 03:28 PM
JPeterman
external usenet poster
 
Posts: n/a
Default

On Sun, 15 Aug 2004 05:57:28 -0400, (Paul) wrote:

In article , JPeterman
biteme@thelibrary wrote:

On Sat, 14 Aug 2004 19:55:28 -0400,
(Paul) wrote:

In article , awtwtw wrote:



As Dave said, the power supply is always a likely source of
failure to boot.

But, one of your other symptoms bothers me a bit. The red LED
on the motherboard is the "AGP_Warn" circuit. It is supposed
to check for an illegal 3.3V only video card, and prevent the
computer from starting. If an illegal (improperly keyed) video
card is present, the PS_ON# signal is prevented from reaching
the power supply, by AGP_Warn.

The AGP_Warn has two ingredients. One I have traced down, so
I know it is there. The TYPEDET# signal from pin A2 on the
video card is connected to one of the transistors. Apparently,
if TYPEDET# is grounded, everything is OK. If TYPEDET# floats,
then that will cause the red LED to light up.

A second ingredient of the check, is the circuit can only
stop the power, if an AGP card is inserted. It would be
inappropriate for the circuit to light the LED, if no video
card is present. So, to do its job, the logic has to be
AGP_Present AND TYPEDET#_floating. I don't know what pin is
checked to verify the card is present.

Now, your symptom of the LED flashing for a moment is weird.
The inputs to AGP_Warn are supposed to be static and unchanging.
Yet, your AGP_Warn lights for a moment and then stops, and
I cannot think of a mechanism for that to happen, unless +5VSB
is going out. And, you said the green LED on the motherboard
stays lit and the fan runs on the back of the case. That means
+5VSB is present and +12V is there to run the fan.

If you have another video card compatible with the board,
try swapping that in. It could be the video card, but as I
say, I cannot really think of a failure mechanism that would
cause the LED to light (indicating trouble) and then
extinguish, unless all power was being lost at the same time.

Paul


Firstly let me thank you for your detailed response. Most of this was
over my head but I understand the gist of it.

The power button on the front of the case will not turn the power off.
I have to hit the switch on the back.
I just tried it again and the red LED on the motherboard will not
flash at all.

I forgot that there is a voice "post reporter" at boot that may tell
me something. I didn't have the speakers on when this happened so I'm
going to try it.

So the power supply may be suspect even though it powers the other two
fans?
I don't have another video card but I have been leaning towards
getting another one.
Thanks again for your patience and time.


Your observation that the switch on the back is needed for control
changes things a bit.

The PSU has several output voltages. Perhaps only one of them is
not working, and the others are. If you own a voltmeter, you can
take a disk drive power connector in hand, and check for +5V and
+12V. If the PSU has a six pin Aux power connector, there will
be a +3.3V pin on it. Those are the major voltages, and I don't
know if the motherboard depends on -5V and -12V in any meaningful
way or not. On my P4C800-E for example, -12V is used by
the serial port, so if -12V dies, my serial port will die, but
the rest of the board will still run. It could be your PSU has
lost +3.3V or +5V.

When using your voltmeter, connect the black lead to a lug on
one of the connectors on the back of the computer. I'm assuming
you have some alligator clips or another clever way to connect it.
The reason is, you don't want to accidently touch the two voltmeter
leads together while working on the power supply. I find with one
red lead in my hand, things are much safer. It is like safety rules
for jumpering car batteries - there is a lot of available current
there if you make a mistake.

I think as Dave said, I'd try a PSU swap first. If the result is
that the red LED stays on, borrow another video card, to see
if it will go off again. If the red LED stays on even with
another video card, it is time to RMA the motherboard. The
AGP_Warn circuit has failed on some motherboards out of the box,
but I've never heard of one dying on a system that was working
for a while.

Your AGP_Warn is just another mystery for the books :-)
I haven't traced the whole circuit, and as those SMT components
are so hard to identify, I probably never will finish it.

HTH,
Paul


Since I don't have a voltmeter or another video card I think I''m
going to buy another power supply. The one I have is a Duro
400 watt supply so I probably won't buy one of these. If that fails
to correct the situation I'' buy a new video card.

Thanks for all of your help. I've got a lot more insight for the
future.


 




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