Hardware Information

The Right Way To Discharge Capacitor In Switch Mode Power Supplies


Switch mode power supply contain some large filter capacitors that can hold dangerous charges even if the unit has not been used for several days. Typical values of this type of filter capacitor are 220uf 250volt and 330uf 400volt! If you are going to work on the power supply circuits, it's a good idea to discharge that capacitor first.

There are three ways to discharge the big filter capacitor in a power supply.

1)Discharge it with a screw driver (not recommended).

The reason for not using the screw driver to discharge a capacitor is because

-the printed circuit board or circuitry can be damage due to the spark generated while discharging the high voltage capacitor. I once blowed the power section using this method. However, if you know that the capacitor stored voltage is not too large, you can easily discharge it with a small screw driver.

-if the capacitor holds a heavier charge of electricity. Discharging the capacitor may melt the tip of the screw driver and the copper on the printed circuit board.

-Sometimes a heavier spark may cause small disintegrated solder lead or copper to fly out from the circuit board and may injured your eyes.

2)Place the leads of a socketed 100 watt electric bulb on the leads of the capacitor.

This method had been used by many technicians around the world for the light bulb will act as an indicator to see if the capacitor still holds the charge. If there is a charge the light bulb will light and after discharged the light bulb will goes off.

3)Place the leads of a high wattage resistor on the leads of the capacitor. I use a 2.2k ohm 10 watt resistor to discharge the high voltage capacitor in a switch mode power supplies. It is simple to use and very effective .It takes only couple of seconds to fully discharge the capacitor.

Conclusion

I strongly suggest for those who use screw driver to discharge a capacitor to swift to the second and third method as these is the safest method to protect the circuit and most importantly is yourself.

Jestine Yong is a electronic repairer and a writer. For more electronic repair information please visit his website at http://www.noahtec.com/electronic-repair-articles.htm


MORE RESOURCES:

NASA Receives First Stage Rocket Hardware for Ares IX Test Flight
MarketWatch - 5 hours ago
10 of important hardware for the Ares IX rocket's upcoming test flight. Called the forward skirt, the component is part of the rocket's first stage. ...


Ars Technica

4.8Gbps USB 3.0 spec finalized; hardware still long way off
Ars Technica, MA - 19 minutes ago
By Joel Hruska | Published: November 17, 2008 - 10:00PM CT The USB 3.0 Promoter Group announced today that the USB 3.0 specification has been finalized, ...


CNET News

Adobe plans to move its software onto ARM hardware
SDTimes.com, CA - 7 hours ago
Adobe will make the AIR runtime and Flash Player 10 for ARM hardware available to OEMs. Flash Player will also be released to partners royalty-free under ...
Adobe strikes deal to bring Flash, AIR to ARM devices Macworld
Adobe Flash 10 support for smartphones in late 2009 infoSync World
Adobe shows ARM-ready Flash 10; Spansion names Apple in suit Apple Insider
EETimes.com - Fiercemobilecontent
all 280 news articles


Carr Hardware Robbery Case Nears Conclusion
Dunn Daily Record, NC - 10 hours ago
The August 2007 case of an attempted robbery at Carr Hardware in Dunn is nearing its resolution as all three defendants have pleaded guilty to their charges ...


Dash Exits PND Hardware To Focus On Licensing
Twice, NY - 12 hours ago
By Amy Gilroy -- TWICE, 11/17/2008 SUNNYVALE, CALIF. — Dash Navigation, the marketers of the first two-way Internet-connected personal navigation device ...


The Money Times

October NPD: Nintendo reigns the hardware sales
The Money Times, India - 13 hours ago
This accounts for a total hardware sales of Nintendo reaching 59.3% (of the industry’s total hardware unit sales). Cammie Dunaway, Nintendo of America’s ...
The Divnich Tapes: Sony Most Affected By Economic Turbulence Gamasutra
Nintendo dominates US hardware chart Digital Spy
October: Gaming Industry Not Affected By The Economic Crisis eFluxMedia
Game Informer - Sci-Tech Today
all 381 news articles


Research and Markets: Analyse the 'IT Selling Opportunities Map ...
MarketWatch - 14 hours ago
... drivers and company level developments and events, we have made the 'IT Selling Opportunities Map' for hardware, software and IT services for Pfizer. ...


Mays Hardware to close
Examiner.com - 1 hour ago
Nov 17, 2008 6:25 PM (4 mins ago) AP FREDERICK, Md. (Map, News) - The owner of Mays Hardware says he is closing the business, which has been in Frederick ...


Extreme Engineering Solutions Introduces XPedite5330: A Low-Power ...
MarketWatch - 15 hours ago
To provide a system designer with multiple hardware options, XPedite5330 is available in a full range of convection- or conduction-cooled configurations. ...


Home Hardware Selects MessageWay for Retail Network Advanced ...
SYS-CON Brasil (Assinatura), NJ - 15 hours ago
MessageWay will be used to manage the exchange of electronic files between more than 1000 retail outlets and the Home Hardware order processing and ...

Hardware - Google News

home | site map
© 2006