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
Latest News
Lenovo Offers Hardware-Based Security In ThinkPad Laptop InformationWeek, NY - By Antone Gonsalves Lenovo on Monday introduced a business notebook with hardware-based security, made possible through a partnership with Intel and ... |
Fitch: US Consumer Products Sector To Face Challenges in 2009 MarketWatch - Appliances, Home, Hardware and Tools: Credit protection metrics for this sector are trending negative. 2009 will be extremely difficult with expected ... Fitch Enhances US RMBS Surveillance with Launch of 'RMBS Loss Metrics' |
More Reliable X360 Hardware Launches Gamespy.com, CA - 1, 2008 Venture Beat's Dean Takahashi has written an article which suggests Microsoft has finally released its new Xbox 360 "Jasper" hardware. ... Xbox 360 Jasper Revision Caught in the Wild Getting a new Xbox 360? Make sure it answers to "Jasper" |
3FN Ups Hardware Swap Capability Web Host Industry Review - Partner with DataPipe – Improve your ROI - Extend your IT resources "Hardware monitoring and replacement services can be the key criteria for successful web ... HostNine Re-Launches New Website |
East Longmeadow Hardware Store Robbed WSHM-TV, MA - By Liz Tufts Employees at the Rocky's Hardware store on North Main Street in East Longmeadow were closing up for the night on Sunday, when they got the ... • Police probe East Longmeadow hardware store robbery East Longmeadow Store Robbed |
Research and Markets: The IT Market in Malaysia Report Can Help IT ... MarketWatch - Further, the overall IT market is segmented into software, hardware, services and communication for the years 2007, 2008, 2009 and 2010. ... |
Apple adds DMCA charge to Psystar suit ZDNet - Adrian Kingsley-Hughes, in a Hardware 2.0 blog entry, posts excerpts of Apple’s amended complaint, highlighting Psystar’s inclusion of an OS X “restore ... Apple adds DMCA charge to lawsuit against Psystar Apple adds DMCA charge to complaint against Psystar Feds Considering DMCA Anti-Circumvention Exemptions |
StudioDave Does A Hardware Review And Meets Ubuntu 8.10 Linux Journal - That machine's audio capabilities were negligible even with external hardware, but it had been serviceable for writing articles and as a portable MIDI ... |
![]() Telegraph.co.uk | On Black Friday, the treasures were found off the beaten path Sky Hi Daily News, CO - I needed some hardware to repair my daughter’s Christmas tree. I avoided to big-name store and found a hardware store that had no lines and a store owner ... Shoppers start early Super Sales: Black Friday on par' — so far Stores entice customers |
![]() SlashGear | Are you ready for Linux? San Jose Mercury News, USA - Some versions, like DSL Linux, are compact and fast, and thus able to run on minimal hardware, including that old 486 PC or Mac you've got stashed in the ... Browser swallows OS gOS Cloud: browser-based OS for Netbooks Good OS Announces Cloud |
Resources
-
All Computer Wholesale, PC Wholesale, Reseller, Wholesaler
Buy computers, software, Hardware, games and accessories from real wholesale companies, be a computer reseller!

