This problem has baffled everyone...

Yo Nick,

I've seen this on 2 puters.

One was my old 486 dx2 66 on god knows which board. When I got it fresh
from the store (I tested it in the store btw and it was fine), it won't
power up at home. So I thought it might be the static from the carpet, and
I put a large piece of aluminum under it and ground that to the screw of the
elec. jack it still won't power up. so I unplugged the AC cord for a bit,
plug it back in and it works fine.

The next day this can't power up thing is gone magically and it runs fine
till I replaced the computer.

Another puter I saw this was with my friend's p3-500, ASUS P3B-F, and cheapo
300W PSU. It started exhibiting what you said, and we did exactly the same
thing you did to try to use it anyway. Until one day, the PSU fan die also.
When we replace the PSU and had to unplug the white AC plug connecting to
the mobo, we noticed that the socket on mobo got rusted. The pins that is,
got rusted. So you know, the mobo's garbage, unless you're desparate enough
to get a socket and solder it.

Anyway, those are the areas you might check. But my final guess is that it
has nothing to do with static or rust. From you saying that it takes the
same time the LED die to a recharge, I am guess something's wrong with the
mobo's capacitor feeding the AC header.

And also try plugging the puter on a completely different elec. outlet, like
the one in the kitchen. Also try a different AC Cord.


-bron


"Nick G" ignore @ nospam.com ¦b¶l¥ó
¤¤¼¶¼g...
The following problem has confounded every IT friend and support person i
have presented it to and appears to defy logic so i am throwing it to a
broader audience of experts to see if it elicits some ideas. Thanks in
advance for considering it and apologies for cross-group posting!

Problem: Spontaneous power-offs that take place between 15 seconds and 30
minutes after booting. As if the power cord was yanked out of the back.
Green M/B LED remains on, power cord has to be disconnected for several
seconds before re-boot can take place.

On Tue, 10 Feb 2004 14:43:51 +0000 (UTC), "Nick G" ignore @ nospam.com
wrote:

snip

PSU
300W unbranded, came with case

You should've never even hooked this one up to a system, especially not
with any of the above video cards. Any number of components could be
damaged because of this power supply. We can hope that didn't happen.

I would tend to agree except that it ran fine with the 9800pro (most recent
addition) for around a month during which the card received intense use (no
o/cing i might add, just lots of games).

I don't think you understand. Not all damage is so immediate as, 1st try,
smoke pours out of box.



400W high quality, multi-fan

Not to be picky, but specific make/model is more useful than telling us,
"high quality, multi fan". For example, some people think Enermax is high
quality, but might not be adequate for the parts you've mentioned above,
due to insufficient 3V/5V rail capacity. I've even seen people claiming
that trashy power supplies, like Kingwin or Turbolink, were high quality.

the 400w PSU is made by Q-Tec and is not running the monitor (separate
power). It is the recommended PSU from Maplin (a specialist UK
tech/electronics components company). I dont think i need more than 400w as
i simply do not have enough components to require that power. however, i do
accept that given the symptoms it may well be that the psu or some other
power problem is at the root of this. The chances, however, of encountering
exactly the same problem with two different PSUs seems remote.

Q-Tec is NOT a high quality power supply.
Your system doesn't need 400W, but, the Q-Tec may not even be able to
supply 300W, regardless of it's labeling. Maplin likely recommends it
because it has the highest profit margin... Some 'sites sell 400W Q-Tec
for less than 1/3 the price of a 430W Antec... ever wonder why?

It's not at all unlikely that you're seeing the same problem from 2
different power supplies, if neither of them can adequate capacity to
supply enough power. You can stack up low (true) capacity power supplies
and see the same problem over and over again, it's not significant that
it's happened with two different units. I cannot be sure this (power
supply) is your problem, but now I certainly wouldn't assume it isn't the
power supply, would take a closer look at that possibility.

Actually, the need to pull the AC from a system usually IS a power supply
problem, either the unit itself or at least an indirect power supply
problem like a board shorting out, a fan shorting out, wires frayed
against a drive cage or similar power issue, where the power supply's
current or voltage monitoring senses the problem and shuts off the supply.

yes, but only in windows or during the install. it has yet to power off
whilst in the bios

Have you ever left it sitting in the bios for extended periods of time?
You might try that if not.

"Alien Zord" wrote in message
...
"Nick G" ignore @ nospam.com wrote in message
...
The following problem has confounded every IT friend and support person
i
have presented it to and appears to defy logic so i am throwing it to a
broader audience of experts to see if it elicits some ideas. Thanks in
advance for considering it and apologies for cross-group posting!

Problem: Spontaneous power-offs that take place between 15 seconds and
30
minutes after booting. As if the power cord was yanked out of the back.
Green M/B LED remains on, power cord has to be disconnected for several
seconds before re-boot can take place.


One of the PCs under my supervision exhibits a similar problem. It very
often shuts down when a CD is inserted into its CDRW drive. It then cannot
be switched ON by pressing the power button, the PSU's rocker switch has
to
be flicked to OFF position for a few seconds then back to ON. Only then
will
the power button work as normal.
ATX mobos have a flip-flop powered by the Vsb line (pin 9) that is under
software and hardware control and sinks the PON line (pin 14) in order to
turn ON the PSU. I suspect that something on the mobo overloads the Vsb
line
causing the FF to release line 14 and go into a latched state.
I shall be looking at this PC in a few hours time so will post my
findings.


I've had my session with the problem PC and this is what I found:
When the PC shut itself down the Vsb remained normal and the PON pin was low
indicating that the PSU was not shut down by the power control flip-flop. In
fact holding the power button for 5 secs reset it to the OFF state and
pressing it again powered up the PC as normal. So the PSU shut itself down
via a different mechanism. Inserting a CD in the troublesome CDRW drive
revealed why. When it spun the disc it sounded like a jet engine even
vibrating the desk itself. The 12V line dropped to 9V indicating a large
current drain and the PSU shut down about half a second later. So an
overload on one of the supply lines can cause the PSU to switch off. Changed
the CDRW (Ionics - a Philips subsidiary) for a Samsung and all is now well.

If you have an access to a multimeter I suggest you check pin 9 (Vsb: +5V)
and pin 14 (PON should be close to 0 when the PC is ON and close to Vsb when
OFF).

Hi,

Was unaware of the residual damage potential. Interesting, thought it does
not necessarily get me closer to id'ing the offending part:
However your PSU points are noted. I do actually suspect that it is
power-related and will have someone check the voltage tomorrow. Guess i
failed to see how a brand new PSU can fail to run what is a pretty ordinary
PC set up...
The bios runs fine for longer than any other configuration but i have not
left it going for over 45 mins or so. will test that now.
Many thanks
N

Q-Tec is NOT a high quality power supply.
Your system doesn't need 400W, but, the Q-Tec may not even be able to
supply 300W, regardless of it's labeling. Maplin likely recommends it
because it has the highest profit margin... Some 'sites sell 400W Q-Tec
for less than 1/3 the price of a 430W Antec... ever wonder why?

It's not at all unlikely that you're seeing the same problem from 2
different power supplies, if neither of them can adequate capacity to
supply enough power. You can stack up low (true) capacity power supplies
and see the same problem over and over again, it's not significant that
it's happened with two different units. I cannot be sure this (power
supply) is your problem, but now I certainly wouldn't assume it isn't the
power supply, would take a closer look at that possibility.

Actually, the need to pull the AC from a system usually IS a power supply
problem, either the unit itself or at least an indirect power supply
problem like a board shorting out, a fan shorting out, wires frayed
against a drive cage or similar power issue, where the power supply's
current or voltage monitoring senses the problem and shuts off the supply.

yes, but only in windows or during the install. it has yet to power off
whilst in the bios

Have you ever left it sitting in the bios for extended periods of time?
You might try that if not.

it appears to close down too quickly to generate a log (think power cord
yanked from the back of the PC).
Have it running on a surge protector and have not noticed any other
electricity supply problems to either houses it was tried in.


1. Have you looked in the event log to see if anything is reported? What
are the last few events in the applications and systems logs.

2. Have you tried running it on an UPS to eliminate any brown outs or
other
power anamolies. A good power supplie should filter most short dips, but
doesn't always happen in real life.

JT

Surge protectors will do nothing about drop outs, and after a few surges
are not effective on surges as well. Have seen some strange problems when
cheap surge protectors fail. An ups will prevent voltage drop outs at the
minimum. The better ones also add filtering and prevent overvoltages as
well.

Either way sounds like a power problem. Could be external, as in loose/bad
connection in surge protector, power cord, etc. Bad power to the wall
socket, etc.. Or interenal such as a bad PSU or a component/drive/fan/light
pulling too much power and causing the PSU to shut down due to the
overload.

JT

On Tue, 10 Feb 2004 16:04:52 +0000 (UTC), "Nick G" ignore @ nospam.com
wrote:

it appears to close down too quickly to generate a log (think power cord
yanked from the back of the PC).
Have it running on a surge protector and have not noticed any other
electricity supply problems to either houses it was tried in.


1. Have you looked in the event log to see if anything is reported? What
are the last few events in the applications and systems logs.

2. Have you tried running it on an UPS to eliminate any brown outs or
other
power anamolies. A good power supplie should filter most short dips, but
doesn't always happen in real life.

JT

In article m,
JT datacare@www wrote:
Surge protectors will do nothing about drop outs, and after a few surges
are not effective on surges as well. Have seen some strange problems when
cheap surge protectors fail. An ups will prevent voltage drop outs at the
minimum. The better ones also add filtering and prevent overvoltages as
well.

Either way sounds like a power problem. Could be external, as in loose/bad
connection in surge protector, power cord, etc. Bad power to the wall
socket, etc.. Or interenal such as a bad PSU or a component/drive/fan/light
pulling too much power and causing the PSU to shut down due to the
overload.

JT


If the OP has any computers in his house that _do_ work he can
prove/disprove the house power+surge protector hyphosis by running the
good computer from the receptacle while testing his parts.

Seems to me that you have to test by substitution, putting parts, one
at at a time, into a known-good system. Unique parts, like the mobo,
memory chips, and CPU, that can't be subsitiution-tested with the
resources available, just have to be tagged as questionable and put on
the shelf for another day.



On Tue, 10 Feb 2004 16:04:52 +0000 (UTC), "Nick G" ignore @ nospam.com




wrote:

it appears to close down too quickly to generate a log (think power cord
yanked from the back of the PC).
Have it running on a surge protector and have not noticed any other
electricity supply problems to either houses it was tried in.


1. Have you looked in the event log to see if anything is reported? What
are the last few events in the applications and systems logs.

2. Have you tried running it on an UPS to eliminate any brown outs or
other
power anamolies. A good power supplie should filter most short dips, but
doesn't always happen in real life.

JT




--
Al Dykes
-----------

kony wrote:
"Nick G" ignore @ nospam.com wrote:

The following problem has confounded every IT friend and support
person i have presented it to and appears to defy logic so i am
throwing it to a broader audience of experts to see if it elicits
some ideas. Thanks in advance for considering it and apologies
for cross-group posting!

Problem: Spontaneous power-offs that take place between 15
seconds and 30 minutes after booting. As if the power cord was
yanked out of the back. Green M/B LED remains on, power cord has to
be disconnected for several seconds before re-boot can take place.

To clairify, every time it powers off, you MUST disconnect AC cord
(or flip PSU rear switch) to get it working again, you can't just
wait a few, say 3 minutes, and it'll come on again?

Wild guess - something is putting spikes on a power line and
triggering a crow-bar shutdown. At least it fits the facts.

--
Chuck F ) )
Available for consulting/temporary embedded and systems.
http://cbfalconer.home.att.net USE worldnet address!

I will hopefully get this checked tomorrow. Thanks v much for keeping me
informed.
Nick

I've had my session with the problem PC and this is what I found:
When the PC shut itself down the Vsb remained normal and the PON pin was
low
indicating that the PSU was not shut down by the power control flip-flop.
In
fact holding the power button for 5 secs reset it to the OFF state and
pressing it again powered up the PC as normal. So the PSU shut itself down
via a different mechanism. Inserting a CD in the troublesome CDRW drive
revealed why. When it spun the disc it sounded like a jet engine even
vibrating the desk itself. The 12V line dropped to 9V indicating a large
current drain and the PSU shut down about half a second later. So an
overload on one of the supply lines can cause the PSU to switch off.
Changed
the CDRW (Ionics - a Philips subsidiary) for a Samsung and all is now
well.

If you have an access to a multimeter I suggest you check pin 9 (Vsb:
+5V)
and pin 14 (PON should be close to 0 when the PC is ON and close to Vsb
when
OFF).

It was tested in two different properties in different parts of London and
on multiple mains sockets. I am writing this in one of those properties and
on a working laptop which is being mains powered with no problems. The most
bizarre thing about this problem is that i have replaced every single major
component at least once if not twice and have still got the problem!

"Al Dykes" wrote in message
...
In article m,
JT datacare@www wrote:
Surge protectors will do nothing about drop outs, and after a few surges
are not effective on surges as well. Have seen some strange problems when
cheap surge protectors fail. An ups will prevent voltage drop outs at the
minimum. The better ones also add filtering and prevent overvoltages as
well.

Either way sounds like a power problem. Could be external, as in
loose/bad
connection in surge protector, power cord, etc. Bad power to the wall
socket, etc.. Or interenal such as a bad PSU or a
component/drive/fan/light
pulling too much power and causing the PSU to shut down due to the
overload.

JT


If the OP has any computers in his house that _do_ work he can
prove/disprove the house power+surge protector hyphosis by running the
good computer from the receptacle while testing his parts.

Seems to me that you have to test by substitution, putting parts, one
at at a time, into a known-good system. Unique parts, like the mobo,
memory chips, and CPU, that can't be subsitiution-tested with the
resources available, just have to be tagged as questionable and put on
the shelf for another day.