Pavilion 7800 no boot

[John Baiamonte]

Hi All,
I have a HP Pavilion 7800 that won't boot up. The green light on the back
of the power supply is on. None of the fans spin, nor any of the drives.
When I push the start button on the front panel the only thing that happens
is the light on the CD-ROM drive blinks. I am hard of hearing so if any
beeps were present I would not hear them.
I would like to check the power supply but forgot what two pins on the
motherboard connector need to be jumped when the connector is unplugged. I
do remember that they were next to each other, if anyone can tell me I would
be most thankful.
Thanks
John

[Ben Myers]

John,

I am not aware of any motherboard which requires jumpers or connectors to be set
differently when the power supply is unplugged. This would be a little odd, but
perhaps HP did choose an oddball motherboard.

As a rule, the fans in a system spin only if the motherboard begins running,
because the fans either draw their power directly from the motherboard or they
are triggered by a circuit on the motherboard.

My best guess is that something is not right with the motherboard, CPU or
memory.

Unplug the power cord whenever you are working on the innards of a computer.

If the system is more than two or three years old, replace the C2032 3v
motherboard battery, and try again. Failed or failing batteries can create all
kinds of wierd symptoms. Also, remove and re-install the memory DIMMs. if one
of them came loose, this could cause problems.

To troubleshoot further, open up the case, and remove all boards (except a video
card, if present), disconnect all external cables (except for keyboard, mouse
and monitor), disconnect all power from floppy diskette, hard drive, and CD-ROM
drive. Of course, remember where all these things connect up. Doing so gets
down to a bare bones motherboard-CPU-memory-video setup. If the motherboard
starts up and displays something on the monitor screen, you know the motherboard
and power supply are good. If not, then you need more sophisticated diagnostic
tools and/or extra parts to determine which component failed. If the board
boots up, reconnect the other devices one at a time. If the system fails to
boot after you connect up a device, disconnect it. It is likely the cause of
failure... Ben Myers

On Tue, 03 Aug 2004 10:54:51 GMT, "John Baiamonte" <donotrespond@all.com> wrote:
Hi All, I have a HP Pavilion 7800 that won't boot up. The green light on the backof the power supply is on. None of the fans spin, nor any of the drives.When I push the start button on the front panel the only thing that happensis the light on the CD-ROM drive blinks. I am hard of hearing so if anybeeps were present I would not hear them. I would like to check the power supply but forgot what two pins on themotherboard connector need to be jumped when the connector is unplugged. Ido remember that they were next to each other, if anyone can tell me I wouldbe most thankful. Thanks John

[John Baiamonte]

Hey Ben,
Thanks a lot for all the info I will follow your advise. The jumper I
was referring to was the 20 pin connector coming from the power supply.
Last year I had another computer fail and I disconnected the 20 pin
connector from the mother board and used a paper clip to connect two of the
pins on the connector and checked the voltages. All the pins were dead,
bought a new power supply and everything worked fine. I just can't
remember what two pin needed to be jumper. If you don't jump the two pins
even a good power supply will test dead.





<ben_myers_spam_me_not @ charter.net (Ben Myers)> wrote in message
news:410f9564.4171820@news.charter.net... John, I am not aware of any motherboard which requires jumpers or connectors to
be set differently when the power supply is unplugged. This would be a little
odd, but perhaps HP did choose an oddball motherboard. As a rule, the fans in a system spin only if the motherboard begins
running, because the fans either draw their power directly from the motherboard or
they are triggered by a circuit on the motherboard. My best guess is that something is not right with the motherboard, CPU or memory. Unplug the power cord whenever you are working on the innards of a
computer. If the system is more than two or three years old, replace the C2032 3v motherboard battery, and try again. Failed or failing batteries can
create all kinds of wierd symptoms. Also, remove and re-install the memory DIMMs.
if one of them came loose, this could cause problems. To troubleshoot further, open up the case, and remove all boards (except a
video card, if present), disconnect all external cables (except for keyboard,
mouse and monitor), disconnect all power from floppy diskette, hard drive, and
CD-ROM drive. Of course, remember where all these things connect up. Doing so
gets down to a bare bones motherboard-CPU-memory-video setup. If the
motherboard starts up and displays something on the monitor screen, you know the
motherboard and power supply are good. If not, then you need more sophisticated
diagnostic tools and/or extra parts to determine which component failed. If the
board boots up, reconnect the other devices one at a time. If the system fails
to boot after you connect up a device, disconnect it. It is likely the cause
of failure... Ben Myers On Tue, 03 Aug 2004 10:54:51 GMT, "John Baiamonte" <donotrespond@all.com>
wrote:Hi All, I have a HP Pavilion 7800 that won't boot up. The green light on the
backof the power supply is on. None of the fans spin, nor any of the drives.When I push the start button on the front panel the only thing that
happensis the light on the CD-ROM drive blinks. I am hard of hearing so if anybeeps were present I would not hear them. I would like to check the power supply but forgot what two pins on themotherboard connector need to be jumped when the connector is unplugged.
Ido remember that they were next to each other, if anyone can tell me I
wouldbe most thankful. Thanks John