Archived from groups: comp.sys.hp.hardware (More info?)

I have a Pavilion XT 868 that will not power on. When I plug in the
power, a green LED on the power unit flashes on for a split second and
then off again.

When I press the power switch on the front, I get nothing-- no front
LED lights, no whirring from the HDD, no fans spinning, no POST beep.

I'm thinking it's the motherboard but need to know how to rule out the
power unit. (I've changed power cable, used a different outlet,
bypassed the surge protector, check the position of the voltage
selector switch, checked all power conections inside the case, and
drained residual power.)

Also, if it is the motherboard, how do I go about choosing the correct
replacement?

Thanks!

-- Christian

Save Darfur -- http://www.savedarfur.org/
World Vision (Darfur) -- http://donate.wvus.org/OA_HTML/xxw [...] em=1072182
ICC (Sudan) -- http://www.persecution.org/Countries/sudan.html

Archived from groups: comp.sys.hp.hardware (More info?)

The XT768 is a microATX chassis with the usual smallish power supply used by HP
in its microATX boxes.

Make sure you do all work of removal and installation of parts with the system
unplugged from external electrical power.

The first step in problem isolation is to disconnect cables and power from
everything except motherboard and video card. Remove all add-in cards such as
modems and sound cards. Make sure that the memory sticks are all firmly placed
in their sockets. Now try to power up the system. If it powers up, the failure
is not due to the tested components, but, instead, the disconnected ones. If
the system fails to power up, the failure is due to a failed motherboard, video
card, processor, memory or power supply. To isolate a single failed component,
substitute them one at a time. Clearly, it's not feasible to swap out the
motherboand CPU, but you can test with a different video card, different or less
memory, or a different power supply.

Problem is that HP often uses power supplies with an extra lead from the
motherboard TO the power supply, to control the power supply fan
thermostatically. Check if your system has one of these 3-pin connectors to the
motherboard. If so, you need an HP or similar replacement power supply for
testing. If not, any good ATX power supply will do for testing, since all you
need to do is connect the power supply to the motherboard and leave it dangling
outside the computer's case.

In short, isolation of causes of failure is not simple unless you have spare
parts to use for testing and sometimes other hardware to use such as a POST
(Power On Self Test) card. If this sounds too difficult, find a local shop that
services systems with AMD CPUs. Not all of them do.

The exact board replacement for your system would be another HP-branded board.
A "near" replacement would be a Asus microATX with Slot A for the CPU. A
not-as-near replacement would be another brand of microATX Slot A.

A newer Athlon or Pentium 4 board would not make sense, because you would also
need to find an HP power supply with the additional required 12v connector to
the motherboard... Ben Myers

On Fri, 08 Apr 2005 23:01:21 -0600, Inky <newsgroupinky@hotmail.com> wrote:

>I have a Pavilion XT 868 that will not power on. When I plug in the
>power, a green LED on the power unit flashes on for a split second and
>then off again.
>
>When I press the power switch on the front, I get nothing-- no front
>LED lights, no whirring from the HDD, no fans spinning, no POST beep.
>
>I'm thinking it's the motherboard but need to know how to rule out the
>power unit. (I've changed power cable, used a different outlet,
>bypassed the surge protector, check the position of the voltage
>selector switch, checked all power conections inside the case, and
>drained residual power.)
>
>Also, if it is the motherboard, how do I go about choosing the correct
>replacement?
>
>Thanks!
>
>-- Christian
>
>Save Darfur -- http://www.savedarfur.org/
>World Vision (Darfur) -- http://donate.wvus.org/OA_HTML/xxw [...] em=1072182
>ICC (Sudan) -- http://www.persecution.org/Countries/sudan.html

Archived from groups: comp.sys.hp.hardware (More info?)

Thanks for the help. I'll try to isolate the problem and then move on
from there. I'll post the results.

-- Christian


On Sat, 09 Apr 2005 13:09:03 GMT, ben_myers_spam_me_not @ charter.net
(Ben Myers) wrote:

>The XT768 is a microATX chassis with the usual smallish power supply used by HP
>in its microATX boxes.
>
>Make sure you do all work of removal and installation of parts with the system
>unplugged from external electrical power.
>
>The first step in problem isolation is to disconnect cables and power from
>everything except motherboard and video card. Remove all add-in cards such as
>modems and sound cards. Make sure that the memory sticks are all firmly placed
>in their sockets. Now try to power up the system. If it powers up, the failure
>is not due to the tested components, but, instead, the disconnected ones. If
>the system fails to power up, the failure is due to a failed motherboard, video
>card, processor, memory or power supply. To isolate a single failed component,
>substitute them one at a time. Clearly, it's not feasible to swap out the
>motherboand CPU, but you can test with a different video card, different or less
>memory, or a different power supply.
>
>Problem is that HP often uses power supplies with an extra lead from the
>motherboard TO the power supply, to control the power supply fan
>thermostatically. Check if your system has one of these 3-pin connectors to the
>motherboard. If so, you need an HP or similar replacement power supply for
>testing. If not, any good ATX power supply will do for testing, since all you
>need to do is connect the power supply to the motherboard and leave it dangling
>outside the computer's case.
>
>In short, isolation of causes of failure is not simple unless you have spare
>parts to use for testing and sometimes other hardware to use such as a POST
>(Power On Self Test) card. If this sounds too difficult, find a local shop that
>services systems with AMD CPUs. Not all of them do.
>
>The exact board replacement for your system would be another HP-branded board.
>A "near" replacement would be a Asus microATX with Slot A for the CPU. A
>not-as-near replacement would be another brand of microATX Slot A.
>
>A newer Athlon or Pentium 4 board would not make sense, because you would also
>need to find an HP power supply with the additional required 12v connector to
>the motherboard... Ben Myers
>
>On Fri, 08 Apr 2005 23:01:21 -0600, Inky <newsgroupinky@hotmail.com> wrote:
>
>>I have a Pavilion XT 868 that will not power on. When I plug in the
>>power, a green LED on the power unit flashes on for a split second and
>>then off again.
>>
>>When I press the power switch on the front, I get nothing-- no front
>>LED lights, no whirring from the HDD, no fans spinning, no POST beep.
>>
>>I'm thinking it's the motherboard but need to know how to rule out the
>>power unit. (I've changed power cable, used a different outlet,
>>bypassed the surge protector, check the position of the voltage
>>selector switch, checked all power conections inside the case, and
>>drained residual power.)
>>
>>Also, if it is the motherboard, how do I go about choosing the correct
>>replacement?
>>
>>Thanks!
>>
>>-- Christian
>>
>>Save Darfur -- http://www.savedarfur.org/
>>World Vision (Darfur) -- http://donate.wvus.org/OA_HTML/xxw [...] em=1072182
>>ICC (Sudan) -- http://www.persecution.org/Countries/sudan.html


Save Darfur -- http://www.savedarfur.org/
World Vision (Darfur) -- http://donate.wvus.org/OA_HTML/xxw [...] em=1072182
ICC (Sudan) -- http://www.persecution.org/Countries/sudan.html