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Holy Moly -- Residual Electricity????
Is there some such concept as "residual electricity"??? There was a problem with a computer at work...it's a new Dell running WinXP Pro...everything's fine, I go to lunch and come back to a blank screen that won't wake up from power-save/sleep mode!! I do the obvious and check connections, making sure they're secure and whatnot. I turn off the computer and turn it back on a few times, to no effect! Tech Support suspects some kind of a "power management" issue -- whatever that is -- and suggests that I leave the system off for a few minutes, literally, to let things "clear"...whatever that means. Sure enough, however: it works! So now I'm here asking, because Tech hasn't the time to puzzle over it with me, WHAT HAPPENED??? And how come shutting off power for a few seconds isn't comparable to leaving power off for a few minutes???????????? TIA! |
#2
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Holy Moly -- Residual Electricity????
In sci.physics Prisoner at War wrote:
Is there some such concept as "residual electricity"??? There was a problem with a computer at work...it's a new Dell running WinXP Pro...everything's fine, I go to lunch and come back to a blank screen that won't wake up from power-save/sleep mode!! I do the obvious and check connections, making sure they're secure and whatnot. I turn off the computer and turn it back on a few times, to no effect! Tech Support suspects some kind of a "power management" issue -- whatever that is -- and suggests that I leave the system off for a few minutes, literally, to let things "clear"...whatever that means. Sure enough, however: it works! So now I'm here asking, because Tech hasn't the time to puzzle over it with me, WHAT HAPPENED??? And how come shutting off power for a few seconds isn't comparable to leaving power off for a few minutes???????????? TIA! Capacitors. -- Jim Pennino Remove .spam.sux to reply. |
#3
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Holy Moly -- Residual Electricity????
wrote in message
news Capacitors. capacitors usually discharge when the current is switched off - their main job is to smooth current, not to store volts.... |
#4
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Holy Moly -- Residual Electricity????
When you turn it off and leave it off for a few minutes, it allows the
capacitors in the power supply to discharge. With the power supply caps discharged, you in effect are guaranteeing a good power on reset when you power on. "Prisoner at War" wrote in message oups.com... Is there some such concept as "residual electricity"??? There was a problem with a computer at work...it's a new Dell running WinXP Pro...everything's fine, I go to lunch and come back to a blank screen that won't wake up from power-save/sleep mode!! I do the obvious and check connections, making sure they're secure and whatnot. I turn off the computer and turn it back on a few times, to no effect! Tech Support suspects some kind of a "power management" issue -- whatever that is -- and suggests that I leave the system off for a few minutes, literally, to let things "clear"...whatever that means. Sure enough, however: it works! So now I'm here asking, because Tech hasn't the time to puzzle over it with me, WHAT HAPPENED??? And how come shutting off power for a few seconds isn't comparable to leaving power off for a few minutes???????????? TIA! |
#5
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Holy Moly -- Residual Electricity????
They discharge, but it can take some time depending on the capacitors.
A few minutes is not at all unusual. -- Jupiter Jones http://www3.telus.net/dandemar http://www.dts-l.org "Gordon" wrote in message ... capacitors usually discharge when the current is switched off - their main job is to smooth current, not to store volts.... |
#6
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Holy Moly -- Residual Electricity????
On Mon, 05 Nov 2007 20:52:31 GMT, "Unknown" wrote: When you turn it off and leave it off for a few minutes, it allows the capacitors in the power supply to discharge. With the power supply caps discharged, you in effect are guaranteeing a good power on reset when you power on. That is my understanding too of capacitors in general !! |
#7
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Holy Moly -- Residual Electricity????
Gordon wrote:
wrote in message news Capacitors. capacitors usually discharge when the current is switched off - their main job is to smooth current, not to store volts.... True, but they don't discharge instantaneously. Ever hear about the "time constant" of an R-C circuit? T = R × C whe T = time constant in seconds R = resistance in ohms C = capacitance in farads The time constant is the time taken for the charging (or discharging) current (I) to fall to 1/e of its initial value (Io). After each time constant the current falls by 1/e (about 1/3). After 5 time constants (5RC) the current has fallen to less than 1% of its initial value and we can reasonably say that the capacitor is fully (dis)charged, but in fact the capacitor takes for ever to (dis)charge fully! -- Lem -- MS-MVP - Networking To the moon and back with 4KB of RAM and 72KB of ROM. http://en.wikipedia.org/wiki/Apollo_Guidance_Computer http://history.nasa.gov/afj/compessay.htm |
#8
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Holy Moly -- Residual Electricity????
"Gordon" wrote in message ... : wrote in message : news : : Capacitors. : : : : capacitors usually discharge when the current is switched off - their main : job is to smooth current, not to store volts.... That shows how much you know -- which is zilch. |
#9
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Holy Moly -- Residual Electricity????
"Androcles" wrote in message
.uk... "Gordon" wrote in message ... : wrote in message : news : : Capacitors. : : : : capacitors usually discharge when the current is switched off - their main : job is to smooth current, not to store volts.... That shows how much you know -- which is zilch. Well rooty toot to you. |
#10
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Holy Moly -- Residual Electricity????
On Mon, 5 Nov 2007 16:36:06 -0500, "Tom Lake"
wrote: "Jupiter Jones" wrote in message news:1xLXi.29858$XF6.22011@edtnps90... They discharge, but it can take some time depending on the capacitors. A few minutes is not at all unusual. You can get some nasty burns from a TV that's unplugged due to those things! Tom Lake Almost sounds like you speak from experience grin. I've unplugged tv's but never had any ill effects from it luckily. Of course I don't open it up either. |
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