PC NO POST -- I'm stumped on this one )o:

[Ian]

Ok lads and lass's,
Here's the problem. my wifes PC WAS working absolutely fine
most of the time but more and more often it started to
switch off with NO warning at all. It then would'nt even POST when
I attempted to restart. No bios screen no hard drive activity no CPU fan.
The PSU fan would be on and the RED HD light would be permanantly lit
until I disconnected both the CD Rom drive and switched the pc off at the
back. It would then boot as normal when I reconnected them.

But as of today it will now not start-up at all. Still PSU fan noise and
permanent
red light at front of case but thats as far as it will go even after being
left unplugged
for 2 hours.


Here's what I've done so far to troubleshoot the problem....
when the machine WAS working of course.

1....Removed cd rom power and ide cables ..still failed after a few days.
2....Booted from floppy and used 2 different DOS ram testers and left them
running
for 10 hours .. NO faults reported.
3....Checked the temp of the cpu which was fairly normal (38c in bios).
4...Within Windows Xp (Sp2) .. ran 3d mark2001 and prime 95 seperately and
together
to try and test CPU/RAM & video card to force a crash .. no failures after
10 hours
of testing.

And these extra things I've tried today in an attept to revive the machine

1 . Disconnected all ide drives .....still no boot
2. Tried working cmos battery ...still no boot

So I've tried ALL I know.. can anybody give me any more ideas .. can the
PSU be dead even if he fan on it is working. and giving out power to the led
?
Does anybody know how to test the drive power connectors with a meter ..
I've got one but I'm not sure which setting to use to test them !!

If more info is required please ask ..if I've forgotten anything !!

PC stats are as follows...
Abit bx6 (rev2)
************
Cpu P2 300 (slot 1)
320mb edo ram
1 Ibm 30gb HD ....own IDE channel
1 DVD rom drive .own IDE channel

Geforce1 256DDR .................................AGP slot
3com Ethernet 10/100 card.......................pci 2
SB 128....................................................pci 4

 

[Michael Hawes]

Ok lads and lass's,
Here's the problem. my wifes PC WAS working absolutely fine
most of the time but more and more often it started to
switch off with NO warning at all. It then would'nt even POST when
I attempted to restart. No bios screen no hard drive activity no CPU fan.
The PSU fan would be on and the RED HD light would be permanantly lit
until I disconnected both the CD Rom drive and switched the pc off at the
back. It would then boot as normal when I reconnected them.

But as of today it will now not start-up at all. Still PSU fan noise and
permanent
red light at front of case but thats as far as it will go even after being
left unplugged
for 2 hours.


Here's what I've done so far to troubleshoot the problem....
when the machine WAS working of course.

1....Removed cd rom power and ide cables ..still failed after a few days.
2....Booted from floppy and used 2 different DOS ram testers and left them
running
for 10 hours .. NO faults reported.
3....Checked the temp of the cpu which was fairly normal (38c in bios).
4...Within Windows Xp (Sp2) .. ran 3d mark2001 and prime 95 seperately and
together
to try and test CPU/RAM & video card to force a crash .. no failures after
10 hours
of testing.

And these extra things I've tried today in an attept to revive the machine

1 . Disconnected all ide drives .....still no boot
2. Tried working cmos battery ...still no boot

So I've tried ALL I know.. can anybody give me any more ideas .. can the
PSU be dead even if he fan on it is working. and giving out power to the led
?
Does anybody know how to test the drive power connectors with a meter ..
I've got one but I'm not sure which setting to use to test them !!

If more info is required please ask ..if I've forgotten anything !!

PC stats are as follows...
Abit bx6 (rev2)
************
Cpu P2 300 (slot 1)
320mb edo ram
1 Ibm 30gb HD ....own IDE channel
1 DVD rom drive .own IDE channel

Geforce1 256DDR .................................AGP slot
3com Ethernet 10/100 card.......................pci 2
SB 128....................................................pci 4

Try another PSU!
Mike.

 

[DaveW]

Sounds like the power supply unit has failed. Yes. The easiest way to test
your system next is to replace the PSU with a known working one of adequate
wattage output.

 

[Ian]

An update to my earlier post...
After leaving it for 10 hours overnight the PC will now post and let me
into bios.
on each boot it now shows post screen detects cpu, harddrive and updates
ESCD then
resets EVERY time.

Also since last post I've tested PSU with multimeter and found it to
accurate
on each Molex connector and also on the ATX 20 pin power connector pins
to what the manual states AND various tech sites on the net.

I've replaced the cpu with another ..Exactly same ..still no boot
I've replaced Video card with another ..still no boot
I've now removed sound card and network card ... still no boot.

I CAN boot with floppy and used the hard drive util from Ibm ..
It passes all manufacturer tests.
When booting from floppy I can "see" the Hardrive and its contents !

So it's even more confusing now .... perhaps the HD boot block is now
corrupt,
but would that make the machine reboot....I would have thought a bad boot
block would
just throw up an error message or something ??

ANYMORE thought fellas ??

 

[Dave]

Ian,

I am a bit confused, so let me make this clear.

You've replaced everything but the motherboard and hard drive, and can get
the machine to POST, but not boot from the hard drive; although, it will
boot from the floppy. So, basically, we are down to a faulty motherboard or
screwed up hard drive.

The motherboard:

First, take a flashlight and look inside the computer at the motherboard.
Remove any obstructions and look for bulging or blown capacitors. They
should be smooth and flat, or slightly recessed, on top. Here is a picture
of some bad capacitiors:

http://www.auroracomputer.ca/images/bad_cap.jpg

Do you see any 'gunk' on the caps? Any that are bulging? Look at all of
them.

Second, did you reset the boot settings in the BIOS, so that the system
boots from the hard disk?

The fact that you had problems starting the computer at all leads me to
think that it is a motherboard problem, though misadjusted BIOS settings and
bad capacitors can cause similar problems.

The Hard Drive:

Do you have a spare hard drive that you can try installing an OS on, to see
if you can boot from it?
If not, can you boot from the DVD Rom?

Dave

 

[Ian]

Thanks for the interst Dave..I'll look at those caps tomorrow in daylight.
I realize my post was Sprawling to say the least !
The main problem WAS...if I can re-word it !

The PC was intemittingly switching off ..no warning at all just a reboot to
a
black screen and a "no Signal" message on monitor.. (no post just red light
on
case and PSU fan spinning ..NO CPU fan spinning)
The only way I found to get it booting again was to remove power cable
& one CDRom IDE cable ..then it booted fine and was fine for several days
(I could reconnect the CDrom again and all would be fine still ) ..then
after several
days/weeks the fault would repeat
Then a few days ago after cutting out .. even the IDE trick didn't work
....DEAD
apart from PSU fan and case lights .
so I left it over night ..and presto in the morning it DID post as normal
but reset after post
screen . I could always "see" the HD contents with a boot discand I've SINCE
realised that
this booting RESET was caused by a screwed XP installation (agp440.sys)
caused by the last cut-out ..as a repair of Xp sorted it out).
So its back to normal completely although without sound card & nic for the
moment .
As before it seems rock steady and will pass all benches/tests I can thow at
it.
But one day I'll simply cut out I'm pretty convinced as I've changed
nothing ..weird !

As you may have read I did TRY another CPU (and cleared bios) and
although it made no
diffrence to the booting problem. I've noticed that when I did all my
probing with my meter when IT was
installed ALL the voltages looked well within the limits.
BUT tonight I've put the original CPU back in and noticed in Bios sensors
(haven't had time
to probe with meter yet) that the +12V was fluctuating from around 8v to no
higher than 11v the whole time I was observing & the CPU fan would slow as
the voltage dropped.
This definatly did not happen with the other CPU installed.
So I'm now thinking that somehow this CPU is dragging the voltage down and
this has been
causing the resetting symptoms described over the last 6 months or so.
Not sure if it possible for this to be the cause .. any ideas ???

Again Cheers for your time !!