On Apr 24, 2009, at 11:33 PM, Ernest L. Gunerius wrote:
> >> On Apr 24, 2009, at 10:03 PM, Meghrouni Vince wrote: >> >>> >>> Does time unplugged diminish the voltage? >>> >>> What should I look for to avoid? I'm sure this may seem >>> obvious, but >>> it is not to me. >> >> I would suggest consulting an expert electrician ... and one that is >> familiar with computer power supplies. The computer repair centers >> sometimes will share info ... even the ones repairing those Windoze >> machines ... I think most power supply's function the same ... >> although there are different styles: >> http://www.atxpowersupplies.com/ >> >> Have you ever started plugging the power cord back into the back of >> the computer, with the other end in an active power strip or wall >> socket, and a NASTY spark jumps out to meet you? I believe that is >> the capacitor(s) discharging. I do not know if this is a way to do >> the deed or not ... I repeat, I do not know. >> >> Just more food for thought. >> >> Bill Connelly >> artsite: http://mysite.verizon.net/moonstoneartstudio >> myspace: http://www.myspace.com/moonstoneartstudio > > If you get a spark when plugging in a power supply that has been > unplugged for at least 30 minutes it is most likely the charging > current recharging the Power Supply Input capacitors. The only > Impedance to input current to the discharged capacitors is the Input > Filter(if present), The Rectifiers and the series resistance(very > small) of the Input Capacitors. > > Thus the turned off and discharged Power Supply looks like a short > circuit to the line voltage and the initial Inrush current can be > quite large and also decays to a small value rapidly as the Voltage > on the Input Capacitors rises. As the Power supply begins to switch > and produce the output voltages(3.3 volt, 5 volt,12 Volt) then an > extra pulse of current is drawn to charge all the capacitors on those > voltages in the Power Supply and the rest of the Computer. > > This all happens quite fast, typically about 2 tenths of a second. > > The Power Supply cannot discharge back through the Power Line. The DC > Voltage is isolated from the Line by the Rectifiers. > > HTH, > > ErnieG OIC. I thought it was discharging through Grounding. Possibly a fatal mistake ... See ... better to ask a Pro! Bill Connelly artsite: http://mysite.verizon.net/moonstoneartstudio myspace: http://www.myspace.com/moonstoneartstudio --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed Low End Mac's G3-5 List, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/g3-5-list?hl=en Low End Mac RSS feed at feed://lowendmac.com/feed.xml -~----------~----~----~----~------~----~------~--~---
