Holy Moly -- Residual Electricity????

Discussion in 'Dell' started by Prisoner at War, Nov 5, 2007.

  1. Prisoner at War

    JimboCat Guest

    I had a Dell notebook whose backlight just wouldn't go on. Removing
    the batteries for an hour didn't help. Removing them for a week (while
    I researched the process for disassembly and replacement of the HV
    source) did! It was all good to go again. Glad I decided to give it
    one more try before taking it apart.

    Somehow it just didn't get the message that the top had been opened,
    and it kept the light off thinking it was closed. Of course, I have no
    evidence that an hour and a quarter wouldn't have done the job...or a
    good bang with a small hammer.

    Jim Deutch (JimboCat)
    JimboCat, Nov 16, 2007
    1. Advertisements

  2. Prisoner at War

    Unknown Guest

    Surely you don't think his head is THAT big?
    Unknown, Nov 16, 2007
    1. Advertisements

  3. Prisoner at War

    w_tom Guest

    Wow. First M.I.5 3/4 says I don't know anything. Then he explains the
    process I specifically defined: Confidence Levels. Why do you
    insult when the point is secondary and trivial;, and when Confidence
    Levels are how virtually all manufacturer capacitors meet (or exceed)

    Confidence Levels are why virtually all capacitors meet or exceed
    specs. Do you know where your 'tables' come from? Please learn
    about confidence levels. Sampling is part of the process so that
    virtually all product meets or exceeds a spec. Charts are given to
    those who don't have a clue beyond Mean, Variance, Standard Deviation.
    - concepts from "Intro to Statistics'. Statistical Process Control
    requires more education. Confidence Levels are why virtually all
    capacitors meet or exceed manufacturer specs.

    It is M.I.5 3/4 who "really don't know anything do you?" M.I.5 3/4 does
    not even know what a Confidence Level is. So he insults others to
    mask his ignorance rather than ask to learn. Then Bwahahs like a
    baby who needs to be fed.

    Meanwhile this (including M.I.5 3/4 ignorance of basic Statistical
    Process Control) is irrelevant. Room temperature has nothing to do
    with creating the OPs problem. Any PC that requires an air
    conditioned room contains hardware defects.
    w_tom, Nov 16, 2007
  4. Prisoner at War

    Androcles Guest

    Yes... and hollow. The distance between his ears is approximately
    5¾"/pi ~= 1.67 with volume of empty space 2.44 cubic inches.
    : Surely you don't think his head is THAT big?
    : : >
    : > : > :
    : > : : > : >
    : > : > : > : > :
    : > : > : : > : > : > Sounds like a short circuit to me. Perhaps he's connecting
    : > : > : > them with the wrong polarity of the "certain type".
    : > : > : >
    : > : > :
    : > : > : It's not a short circuit as such, just a lower resistance in
    : > parallel
    : > : >
    : > : > If you connect a copper wire or a solder splash across the cap
    : > : > you'd be connecting a lower resistance in parallel, even copper
    : > : > wire has some resistance. That's a short circuit by definition.
    : > : >
    : > :
    : > : So?
    : >
    : > So it is a short circuit of "the certain type" "as such", contrary to
    : > hand-waving waffle. What's the 5¾ for? Not your hat size, surely?
    : >
    : >
    Androcles, Nov 17, 2007
  5. Prisoner at War

    AnimalMagic Guest

    The "soft switch" of the laptop lid fired a transistor which turns the
    HV source on.

    Banging it with a hammer would merely produce a dent.
    AnimalMagic, Nov 17, 2007
  6. Prisoner at War

    Saucerhunter Guest

    Holy pulse capacitors. Batman!! Wanna try blowing something to hell??
    Or maybe a good Marx generator will do.
    Saucerhunter, Nov 17, 2007
  7. Or a huge, charged pulse cap.

    Wouldn't "reducing voltage fluctuations" also cause the current to be
    "smoothed" as well? Simple Ohm's law would say yes. If voltage peaks or
    "fluctuations" are reduced, then so too would be the instantaneous
    currents associated with the circuit that said "reduced fluctuation"
    voltages are passing though.
    GoldIntermetallicEmbrittlement, Nov 17, 2007
  8. Prisoner at War

    TheKraken Guest

    There is a such thing as an overtly crosspoting Usenet retard!

    You qualify!
    TheKraken, Nov 17, 2007
  9. Prisoner at War

    jimp Guest

    Yes, but you are confusing cause and effect.
    jimp, Nov 17, 2007
  10. Prisoner at War

    bstrom1953 Guest

    Capacitors store charge, not volts.
    bstrom1953, Nov 18, 2007
  11. Prisoner at War

    krw Guest

    No. The reason the voltage is fluctuating is because the current is
    fluctuating. The capacitor supplies the "surge" current when the
    load demands it (but the supply, can't). It effectively lowers the
    impedance of the supply but doesn't reduce current fluctuations,
    Indeed may increase them.
    krw, Nov 18, 2007

  12. Absolutely not. The term "smoothing cap" is valid, and has been in use
    in the power supply industry for decades. The fucking "effect" doesn't
    matter. Both voltage ripple as well as current ripple is reduced.

    They are goals, not "effects".
    GoldIntermetallicEmbrittlement, Nov 18, 2007
  13. Prisoner at War

    jimp Guest

    Absolutely not. The term "smoothing cap" is valid, and has been in use
    in the power supply industry for decades. The fucking "effect" doesn't
    matter. Both voltage ripple as well as current ripple is reduced.[/QUOTE]

    The whole point of capacitors on a voltage source is to keep the
    voltage constant, effectively lowering the power source internal
    resistance, under a changing load, which means the current changes
    with the load; it isn't "smoothed".

    You haven't a clue what you are talking about.
    jimp, Nov 18, 2007

  14. The current signatures of many of my power supply designs state that
    you are incorrect.

    If you spend years characterizing power supplies, you understand.

    Perhaps you haven't, and hence, you don't.
    ChairmanOfTheBored, Nov 18, 2007
  15. Prisoner at War

    jimp Guest

    The current signatures of many of my power supply designs state that
    you are incorrect.[/QUOTE]
    I retired from designing and characterizing power supplies years ago.
    Perhaps you are just a foul mouthed snot.
    jimp, Nov 18, 2007
  16. Prisoner at War

    Don Kelly Guest

    It appears that "saucerhunt" and "krw" are looking at different currents.
    The load voltage (and hence current) is smoothed (otherwise there is no
    point to having a capacitor) but the total current from the rectifier will
    "fluctuate" more- higher peaks and discontinuous current pulses even though
    the output voltage fluctuates less than without capacitors.

    Don Kelly
    remove the X to answer
    Don Kelly, Nov 19, 2007

  17. An easy proof is a low power HV supply. One designs them ONLY with
    enough stored energy to do the customer spec.

    We use the same supply for a high precision, 0.00006% ripple X-Ray
    supply as we do for the higher ripple, higher power unit. The only
    difference is that the high precision unit has an RC network on the
    output, which makes for very low ripple, but cannot handle much loading
    over a couple uA, yet the same supply with "storage caps" across the
    output will push several uA, but have a slightly greater ripple.

    One is to make for a very clean X-Ray flux emission where the cleaner
    the DC rail is, the cleaner the electron beam striking the target is, and
    the cleaner the X-Ray flux will be, and, and the other is for pushing a
    Geiger counter where a fair deal of ripple in the output rail is
    perfectly tolerable for proper , precise circuit operation. Same supply,
    different output stage, different results.
    ChairmanOfTheBored, Nov 19, 2007
  18. Prisoner at War

    krw Guest

    What exactly do you call "keep the voltage constant", other than
    Perhaps you were too quick in forgetting what you did?
    Well, now there you got me.
    krw, Nov 19, 2007
  19. Prisoner at War

    krw Guest

    Not at all. Think about a load like a microprocessor. The current
    of the load may fluctuate a couple of orders of magnitude. The
    current varies all over the place but the voltage can't.

    Of course the capacitor may increase the current in the rectifier
    considerably, as well.
    krw, Nov 19, 2007
  20. Prisoner at War

    jimp Guest

    Regulation, which is something different.

    The big capacitors in a power supply remove the ripple component by
    virtue of forming a simple RC low pass filters.

    Before most of the people here were born, the output section of a DC
    power supply was invariably a Pi filter with two shunt "condensors"
    and a series inductor.

    With the availability of cheap, high value capacitors, the Pi section
    and heavy, expensive inductor were replaced with one big ass capacitor
    and people stopped going through the calculations to come up with the
    optimal Pi section at the least cost.
    Not likely, DC power supply design is trivial for the most part.

    The only non-trivial one I was involved with was a 3 phase switcher
    that put out 35 volts with a 100 amp pulse load with millvolts ripple
    and the only non-trivial problem with that was reliable start up sequencing.
    jimp, Nov 19, 2007
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.