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

Discussion in 'Dell' started by Thomas G. Marshall, Feb 12, 2005.

  1. Thomas G. Marshall

    Sparky Guest

    Maybe GE's were designed to handle the power off/power on sequence
    better than the IBM iron? After all, they "bring good things to life".
    Sparky, Feb 18, 2005
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  2. Thomas G. Marshall

    w_tom Guest

    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

    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, Feb 19, 2005
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  3. Thomas G. Marshall

    w_tom Guest

    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

    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 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
    w_tom, Feb 19, 2005
  4. Thomas G. Marshall

    w_tom Guest

    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

    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.
    w_tom, Feb 19, 2005
  5. w_tom coughed up:
    That's right. But you said this (you snipped it out):

    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, Feb 19, 2005
  6. Roger Wilco coughed up:

    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, Feb 19, 2005
  7. w_tom coughed up:
    Because a paper clip is designed to be flexed, but not designed to be flexed
    10,000 times.

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

    Damage of Thermal Deltas > Damage of Thermal Stasis.

    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.
    Thomas G. Marshall, Feb 19, 2005
  8. Thomas G. Marshall

    Roger Wilco Guest

    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.
    Not at 13 - back then I was ripping the audio amplifiers out for my
    homemade stereo cludges. :)
    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
    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
    Roger Wilco, Feb 19, 2005
  9. Thomas G. Marshall

    w_tom Guest

    50,000 volts? What was that? An ignition system? A
    w_tom, Feb 19, 2005
  10. Thomas G. Marshall

    Roger Wilco Guest

    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.
    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. :)
    Roger Wilco, Feb 19, 2005
  11. 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...

    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.
    Thomas G. Marshall, Feb 20, 2005
  12. Thomas G. Marshall

    w_tom Guest

    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?
    w_tom, Feb 20, 2005
  13. w_tom coughed up:


    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.

    Thomas G. Marshall, Feb 20, 2005
  14. Thomas G. Marshall

    Roger Wilco Guest

    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...


    Also mentioned is thermal cycling as it pertains to fuses.
    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. :)
    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
    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?

    Roger Wilco, Feb 21, 2005
  15. Thomas G. Marshall

    Roger Wilco Guest

    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.
    I was okay the next day (didn't sleep very well) - but much more
    apprehensive and cautious.
    No. This was a military establishment and I wasn't put under any
    Roger Wilco, Feb 21, 2005
  16. Thomas G. Marshall

    Roger Wilco Guest

    "Thomas G. Marshall"
    That static charge (socks and carpet) is quite high in voltage too as I
    understand it. :)

    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. :)
    Roger Wilco, Feb 21, 2005
  17. Roger Wilco coughed up:
    Sounds familiar :) . Walk into the light roger...walk into the light....
    Thomas G. Marshall, Feb 21, 2005
  18. 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...
    Stuart Krivis, Mar 14, 2005
  19. 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.

    Thomas G. Marshall, Mar 14, 2005
  20. Thomas G. Marshall coughed up:
    'course I'm reffering to a consumer radio battery, not some 400A thing you
    probably have in your basement :)

    Thomas G. Marshall, Mar 14, 2005
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