Leaving Dell Dimension 8300 running 24/7 ...?

[w_tom]

The observation is a failed computer. That tells us nothing
about why failure happened nor anything else that is
inciteful. Any claim that failure was caused due to power
cycling is classic speculation.

Observation alone was never sufficient to create a
conclusion. At best, observation alone only creates
speculation - and too often myths.

But we have a world full of only oberservations. The
management saw the space shuttle launched just fine in
sub-freezing weather. That alone was sufficient for a
conclusion that all shuttles could launch when it was that
cold. Therefore any and every engineer who objected was
ignored. What do engineers know. We had observations. We
called the explosion Challenger.

Those aluminun tubes were observed. Therefore they must be
for manufacturing weapons of mass destruction. Clearly that
was an irrefutible conclusion because we had observations.

Those trucks were configured so they could be used to create
bio-chemical weapons. Therefore they clearly were for WMDs.
Again, that must be a valid conclusion. We observed those
trucks.

Light bulbs would always fail when powered on. That alone
is proof that power cycling caused the light bulb failure.
Even the light bulb industry says that observation is wrong.

Observation is sufficient - at best - only for speculation.
We use speculation - tempered by other concepts, numbers, and
facts - to form hypothesis. Then later, we experiment, obtain
the necessary numbers, and eventually learn facts. Exactly as
taught in junior high school science. Based upon information
from that building of 2000 computers, we can only speculate.
When we apply that speculation to other concepts, numbers, and
facts, then the hypothesis does not stand.

In the meantime, experience from discovering why failures
happen - also tempered by concepts, numbers, and data sheets -
says power cycling is not destructive in the short one decade
life of that computer.

Observation alone is never a conclusion. Observation
without corresponding numbers and other relevant details is
called junk science speculation.

 

[w_tom]

Again, thermal cycling must not create feedthrough
failure. Thermal stress that created a feedthrough failure
is due to a defect from the factory. A defect long since made
extinct by good design and current manufacturing practices.

Can thermal cycling eventually cause a feedthrough failure?
Yes. And then we apply numbers. Not in the life time of
those electronics.

Thermal stress on a PC Board? Yes, when the board is
exposed to hundreds of degrees of molten solder. Not in
trivial, single digit temperature changes during normal
operation.

Yes, all appliances can be damaged by power cycling. And
then we apply numbers. For example, power switches are
typically rated for 100,000 power cycles. That is seven
times, every day, for ....
39 years. IOW once we apply the numbers, then damage due to
power cycling is irrelevant. And that was the point. The
numbers - those details - are necessary to put things into
perspective. Observation alone can only provide - at best -
speculation.

Speculation will tell us power cycling is destructive.
Details such as the numbers - 100,000 cycles - tells us that
destructive power cycling is also completely irrelevant.

Again, if power cycling was so destructive, then those who
have seen this damage could then tell us what is damaged by
power cycling. With such details (ie the power switch), then
power cycling was demonstrated irrelevant to failure.

How long have I been repairing things? Did you fix TVs at
the age of 13 ... and when TVs were using vacuum tubes? I've
got a wee bit experience attached to these degrees. When was
the last time you were shocked by the B+. For those who are
still a little wet behind the ears - that is about 250 volts
DC.

 

[w_tom]

It was not a thermal fuse. It was a standard 250 volt glass
cartridge line fuse. It failed because it was defective (for
the function) by design. And yet, using only observation, one
would assume it failed due to thermal cycling.

Again, as in that above power switch example, thermal
cycling does cause failures. And then we apply the numbers.
Numbers say that failure rate is completely irrelevant.
Machines will have long since gone to the landfill.

Why do I fixated on components? Because that is where
investigations start to solve problems. In other sciences,
the best evidence is also the dead body. Without going right
down to the reason for that failure - the component - then one
cannot say why failure happened. One cannot eliminate or
reduce failures without first learning why those failures
happen. Again, its called best evidence - the dead body.

What is this fixation with thermal stress for trivial
temperature changes. If component must be designed to
withstand 500 degrees from molten solder, then why would
single digit temperature changes be destructive? Yes, thermal
cycling is destructive. But no one reading this will exist to
witness that failure. Again, the perspective provided by
numbers.

The numbers - those pesky details. Its a problem we
engineers have. Those numbers just will not go away as long
as we must live with reality.

 

[Thomas G. Marshall]

w_tom coughed up:

The observation is a failed computer. That tells us nothing
about why failure happened nor anything else that is
inciteful.

That's right. But you said this (you snipped it out):

w_tom:
IOW observation - that the computer failed due
to power cycling - was found erroneous once
we add underlying details.


Which is not observation at all. The minute you said "due", it became a
conclusion that you were at odds with.

I only point this out because you were supplying an enormous amount of words
leading up to a point, one that may be just fine (I'm not sure yet), but
then seemed to *completely* sabotage it all at the end by counter-defining
your own definitions. I only pointed out that /that/ is where some of the
confusion lay.

 

[Thomas G. Marshall]

Roger Wilco coughed up:

....[rip]...

And
that is the point. Those who claim power cycling is so
destructive don't learn the whys - they only speculate. IOW
they are easily deceived by the myths of power cycling rather
than acutally learn facts. Again, what component is being
damaged by power cycling?

The "wear" part of "normal wear and tear" is increased on some
components by this - while other components may see decreased wear by
it. Overall, it probably doesn't matter either way in most high
quality modern computers.

When you look at all things in physics, I suspect that you'll see that all
state deltas have cascading effects.

Let me use rampant speculation, since all of this hoo hah is nearly
impossible to prove, "numbers" or not:

As I type on my keyboard, the minute flex that it is inducing in the table
regardless of strength, is wearing it out. I suspect that if I were to
simply hold down the shift key, that it is less so, simply because the bend
in the desk not required to cycle. Basically, 1 delta is easier for it to
bear than multiples.

As current shows up in a conductor, the electron propagation necessarily
wanders to the edge. It is the nature of electrons to repel each other.
All conductors, other than mystical perfect superconductors, resist to some
degree. This resistance results in heat and EM emission. The heat appears
greater at the edges causing the conductor to expand and contract
non-uniformly. I suspect that this repeated flex in the outer shell of the
conductor weakens it compared to a single flex, even if that flex is firmly
within spec.

As I search and search for something that can handle multiple deltas as
easily as a single, I come up empty. I think of a single delta not having a
wear effect, I also come up empty, but maybe with this one below. {shrug}.
And multiple deltas here are assumed by me to be worse than single deltas.

A wagon wheel with its axel buried in the ground so that it is free to spin
like a top. A bunch of 3 foot ropes attached to the edge of the wagon
wheel, one at every 10 degrees around the circle, emanating from the edge of
the wheel at a tangent. Each one is pulled gently. This will still place
/uneven/ stress on the wheel and its bearings, even if the bearings were
mystically tight and friction free. All within enormously minute metrics,
but it would still be there.

 

[Thomas G. Marshall]

w_tom coughed up:

news:[email protected]...

....[rip]...

What is this fixation you have for components? It is what is
in-between these components (what connects them) that is most
affected. A physical trait of dissimilar materials is that they
expand and contract with temperature with differing amounts even
though they are physically connected (and often rigidly).

....[rip]...

Why do I fixated on components? Because that is where
investigations start to solve problems. In other sciences,
the best evidence is also the dead body. Without going right
down to the reason for that failure - the component - then one
cannot say why failure happened. One cannot eliminate or
reduce failures without first learning why those failures
happen. Again, its called best evidence - the dead body.

What is this fixation with thermal stress for trivial
temperature changes. If component must be designed to
withstand 500 degrees from molten solder, then why would
single digit temperature changes be destructive?

Because a paper clip is designed to be flexed, but not designed to be flexed
10,000 times.

Yes, thermal
cycling is destructive. But no one reading this will exist to
witness that failure.

Ok, so it's clearly a question of whether this is true:

Damage of Thermal Deltas > Damage of Thermal Stasis.

Again, the perspective provided by numbers.

The numbers - those pesky details. Its a problem we
engineers have. Those numbers just will not go away as long
as we must live with reality.

The /meaning/ of those numbers is what is being argued about. *Meaning*.
You remind me of someone using statistics for political arguments. As if
the statistics /without interpretation/ mean something.

 

[Roger Wilco]

Again, if power cycling was so destructive, then those who
have seen this damage could then tell us what is damaged by
power cycling. With such details (ie the power switch), then
power cycling was demonstrated irrelevant to failure.

I agree with this, but you seemed to be saying before that cycling
didn't cause failure at all (without numbers) not that the failure was
irrelevant in the normal useful life of the equipment.

How long have I been repairing things? Did you fix TVs at
the age of 13 ... and when TVs were using vacuum tubes?

Not at 13 - back then I was ripping the audio amplifiers out for my
homemade stereo cludges.

I've
got a wee bit experience attached to these degrees. When was
the last time you were shocked by the B+.

I've been out of the industry for some time now. The most modern
consumer electronics gizmos I worked on were CLV and CAV videodisc
players. You (readers) may not have ever seen any of those because they
quickly went the same way as the 8-track (and 4-track) endless loop
audiocassettes.

For those who are
still a little wet behind the ears - that is about 250 volts
DC.

I was hit by 50,000 VDC once, I was lucky that the muscle reation was to
pull away - even so, I was very sick (nausea and nervous tremors) for a
long while after - I thought I was just taking a long time to die from
it.

 

[w_tom]

50,000 volts? What was that? An ignition system? A
microwave?

 

[Roger Wilco]

50,000 volts? What was that? An ignition system?

As you know, voltage means very little - ignition coil voltage will
measure about 1 volt with a multimeter due to the short on period of the
duty cycle.

A microwave?

High power HF transmitter (Collins IIRC A/N designation FRT-85C Fixed
Radio Transmitter). I think the FPA was capable of 250 kilowatts and the
50k I caught was plate or screen grid voltage.

Anyway - I think it damned near killed me. I always kept my elbow to
ground while tweaking and the path was from ring finger to elbow to
chassis ground ( and my travel path ended some ten feet away from the
unit). The fact that I was contacted on the outside of the ring finger
(near the knuckle) caused me to recoil back and away instead of grasping
which would have been deadly.

Strangely your mentioning being shocked brought back fond memories of
antics in my past.

 

[Thomas G. Marshall]

Roger Wilco coughed up:

As you know, voltage means very little

Right. I was wondering if it was static charge from rubbing your socks on
the carpet. Though I'm betting that wouldn't have made you feel so sick...

- ignition coil voltage will
measure about 1 volt with a multimeter due to the short on period of
the duty cycle.


High power HF transmitter (Collins IIRC A/N designation FRT-85C Fixed
Radio Transmitter). I think the FPA was capable of 250 kilowatts and
the 50k I caught was plate or screen grid voltage.

Anyway - I think it damned near killed me. I always kept my elbow to
ground while tweaking and the path was from ring finger to elbow to
chassis ground ( and my travel path ended some ten feet away from the
unit). The fact that I was contacted on the outside of the ring finger
(near the knuckle) caused me to recoil back and away instead of
grasping which would have been deadly.

Strangely your mentioning being shocked brought back fond memories of
antics in my past.

When I was a kid, one of our house's 50A fuses blew. (no circuit breaker on
this house for some reason---old design). Big fat very old looking
horizontal tube for a fuse, held at both ends, in a waterproof box on the
outside of the house. Now this is 110V A/C, so of course no where near as
horrifying as your DC jolt. But still enough to fry you into the emergency
room, or morgue.

So here I am outside trying to figure out how to remove this sucker and
replace it with a new one. Hmmm..... Sucker is in there tight. Can't get
it out from the middle, the ends are held in the clips like cement. And I
cannot shut the power source off (I forget why). So I said to meself:
"self, if you are careful, you can take this handy screwdriver and prie it
directly out of one of the metal clips, and it won't hurt you if you hold
only the plastic handle."

Worked fine, until I tried to use the edge of the fusebox for leverage.

 

[w_tom]

When it comes to electrocution, current is the important
number. And not just current through the body. As explained
by a medical doctor, the amount of current locally through
vital organs AND (in the case of the heart) the period
(relative to organ cycles) that current passes through.

Electricians with good training or too many previous events
work with electrically taped tools AND one hand in the back
pocket (no current path through the heart).

When shocked by 50,000+ volts, some appear to have longer
lasting problems. IOW I suspected that the higher voltage
could penetrate or adversely effect what would normally be
less conductive nervous system cells. This being a hypothesis
to explain why some shocked by much higher voltages can
require a month plus to fully recover.

How long were adverse effects from that transmitter? Did
you have some way to externally measure your mental abilities
in the days and months after the event?

 

[Thomas G. Marshall]

w_tom coughed up:

....[rip]...

When shocked by 50,000+ volts, some appear to have longer
lasting problems. IOW I suspected that the higher voltage
could penetrate or adversely effect what would normally be
less conductive nervous system cells.

Too many variables.

Nerves work by sodium and potassium ion interchange. They are essentially
long tubes with holes which allows either ion to flow in and out of the
membrane, everywhere there isn't myelin to insulate. The cascade of this
interchange starts at one end and flows to the other. It's the speed of
this ripple which is the nerve speed.

During this process, the "action potential" of the nerve membrane is
measured from roughly -70 mV to +55 mV. Tiny potentials, enough for the K+
and Na+ (both single positive charges) to shift places. These ions are let
through specific "gates", the holes in the tube, dedicated for each ion.

I can easily imagine these gates becoming damaged, or even charged, to the
point where it is difficult for the ions to pass, or that fewer gates
actually function correctly.

....[rip]...

 

[Roger Wilco]

It was not a thermal fuse. It was a standard 250 volt glass
cartridge line fuse.It failed because it was defective (for
the function) by design.

But you said "The manufacturer so undersized a fuse that in a warm room,
the fuse would blow" - if ambient tenperature is a factor it seemd to me
that thermal fuses were the subject. Anyway, most fuses are meltable (or
vaporizable) links. They don't use nanotech robots to dismantle the
bridge.

You had me Googling and I found a mention of lightbulbs...

http://www.wizard-labs.com/fuse_to_install.html

Also mentioned is thermal cycling as it pertains to fuses.

And yet, using only observation, one
would assume it failed due to thermal cycling.

Again, as in that above power switch example, thermal
cycling does cause failures. And then we apply the numbers.
Numbers say that failure rate is completely irrelevant.
Machines will have long since gone to the landfill.

Engineering has come a long way in its quest to increase the mean time
between failures, but that does not eliminate the problem of thermal
cycling it only mitigates it. I agree that thermal cycling is not so
much an issue when numbers (especially with regard to the time involved)
are brought to bear. My computer has been on and off several times daily
for about ten years without failure - but it was practically obsolete by
the time it was taken out of the box.

Why do I fixated on components? Because that is where
investigations start to solve problems.

Sometimes failed components are the symptoms of the problem and the real
problem is inadequate design albeit state-of-the-art at the time of said
design.

In other sciences,
the best evidence is also the dead body. Without going right
down to the reason for that failure - the component - then one
cannot say why failure happened. One cannot eliminate or
reduce failures without first learning why those failures
happen. Again, its called best evidence - the dead body.

What is this fixation with thermal stress for trivial
temperature changes. If component must be designed to
withstand 500 degrees from molten solder, then why would
single digit temperature changes be destructive?

Single digit?? What temperature scale are you using that yeilds a single
digit change between up-and-running for several hours and deenergized
for several hours.

In addition to temperature considerations there is heat. If repeated
thermal stress between the heatsink and the device using that keatsink's
heat capacity causes the interface to lose contact the loss of heat (the
flowing of thermal energy) will give rise to excessive temperature in
the device. Heat-sink compound (is that a component?) is used to lessen
this possibility. Would you look at the charred device and say the
failure was caused by inadequate design? Or would you look past the
symptom to the real cause?

[snip]

 

[Roger Wilco]

When it comes to electrocution, current is the important
number. And not just current through the body. As explained
by a medical doctor, the amount of current locally through
vital organs AND (in the case of the heart) the period
(relative to organ cycles) that current passes through.

Electricians with good training or too many previous events
work with electrically taped tools AND one hand in the back
pocket (no current path through the heart).

This case was my fault in that I neglected to use the shorting probe and
relied on the bleeder resistors/voltage divider circuit to have drained
the charge. The bleeder closest to ground was open leaving the charge on
the remaining divider resistors. I was working in the IPA where the
voltage divider tapped off for ... I forget what reason.

When shocked by 50,000+ volts, some appear to have longer
lasting problems. IOW I suspected that the higher voltage
could penetrate or adversely effect what would normally be
less conductive nervous system cells. This being a hypothesis
to explain why some shocked by much higher voltages can
require a month plus to fully recover.

How long were adverse effects from that transmitter?

I was okay the next day (didn't sleep very well) - but much more
apprehensive and cautious.

Did
you have some way to externally measure your mental abilities
in the days and months after the event?

No. This was a military establishment and I wasn't put under any
observation.

 

[Roger Wilco]

"Thomas G. Marshall"

Roger Wilco coughed up:


Right. I was wondering if it was static charge from rubbing your socks on
the carpet. Though I'm betting that wouldn't have made you feel so sick...

That static charge (socks and carpet) is quite high in voltage too as I
understand it.
[snip]

When I was a kid, one of our house's 50A fuses blew. (no circuit breaker on
this house for some reason---old design). Big fat very old looking
horizontal tube for a fuse, held at both ends, in a waterproof box on the
outside of the house. Now this is 110V A/C, so of course no where near as
horrifying as your DC jolt. But still enough to fry you into the emergency
room, or morgue.

So here I am outside trying to figure out how to remove this sucker and
replace it with a new one. Hmmm..... Sucker is in there tight. Can't get
it out from the middle, the ends are held in the clips like cement. And I
cannot shut the power source off (I forget why). So I said to meself:
"self, if you are careful, you can take this handy screwdriver and prie it
directly out of one of the metal clips, and it won't hurt you if you hold
only the plastic handle."

Worked fine, until I tried to use the edge of the fusebox for

leverage.

I was surprised by 110 AC when I was a kid. I suppose that is how I got
interested in electrical and electronic things - like a moth to the
flames.

 

[Thomas G. Marshall]

Roger Wilco coughed up:

"Thomas G. Marshall"
message
....[rip]...

Worked fine, until I tried to use the edge of the fusebox for
leverage.

I was surprised by 110 AC when I was a kid. I suppose that is how I
got interested in electrical and electronic things - like a moth to
the flames.

Sounds familiar . Walk into the light roger...walk into the light....

 

[Stuart Krivis]

How long have I been repairing things? Did you fix TVs at
the age of 13 ... and when TVs were using vacuum tubes? I've
got a wee bit experience attached to these degrees. When was
the last time you were shocked by the B+. For those who are
still a little wet behind the ears - that is about 250 volts
DC.

Never. I was always careful.

B+ can be quite a bit higher than that too, although it's hard to get
condensers rated for 500 or more VDC these days...

 

[Thomas G. Marshall]

Stuart Krivis coughed up:

Never. I was always careful.

B+ can be quite a bit higher than that too, although it's hard to get
condensers rated for 500 or more VDC these days...

That's nothing. Have you ever licked a nine volt battery?

I told my wife once that you can quickly test if a 9v was dead by touching
the terminals briefly to your tongue. I assured her it was "going to be
ok". She tried it and ran from the room screaming with her arms in the air.
She was clearly more sensitive to it than I was.


--
Iamamanofconstantsorrow,I'veseentroubleallmydays.Ibidfarewelltoold
Kentucky,TheplacewhereIwasbornandraised.ForsixlongyearsI'vebeenin
trouble,NopleasureshereonearthIfound.ForinthisworldI'mboundtoramble,
Ihavenofriendstohelpmenow....MaybeyourfriendsthinkI'mjustastrangerMyface,
you'llneverseenomore.ButthereisonepromisethatisgivenI'llmeetyouonGod's
goldenshore.

 

[Thomas G. Marshall]

Thomas G. Marshall coughed up:

Stuart Krivis coughed up:

That's nothing. Have you ever licked a nine volt battery?

I told my wife once that you can quickly test if a 9v was dead by
touching the terminals briefly to your tongue. I assured her it was
"going to be ok". She tried it and ran from the room screaming with
her arms in the air. She was clearly more sensitive to it than I was.

'course I'm reffering to a consumer radio battery, not some 400A thing you
probably have in your basement

--
Iamamanofconstantsorrow,I'veseentroubleallmydays.Ibidfarewelltoold
Kentucky,TheplacewhereIwasbornandraised.ForsixlongyearsI'vebeenin
trouble,NopleasureshereonearthIfound.ForinthisworldI'mboundtoramble,
Ihavenofriendstohelpmenow....MaybeyourfriendsthinkI'mjustastrangerMyface,
you'llneverseenomore.ButthereisonepromisethatisgivenI'llmeetyouonGod's
goldenshore.

 

[timberlandko]

Just an off-the-wall observation re consumer 9V batteries - a fresh one with
exposed contacts in a pocketful of loose change can bring about a real
attention-getter.