{"id":836,"date":"2014-04-22T11:10:45","date_gmt":"2014-04-22T18:10:45","guid":{"rendered":"https:\/\/www.circuitspecialists.com\/blog\/?p=836"},"modified":"2021-02-12T13:46:32","modified_gmt":"2021-02-12T20:46:32","slug":"discharge-capacitors-in-switch-mode-power-supplies","status":"publish","type":"post","link":"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/","title":{"rendered":"How to Discharge Capacitors in a Switched-Mode Power Supply"},"content":{"rendered":"
Here is a short tutorial on how to discharge the capacitors in a power supply so you can safely repair it:<\/h6>\n
    \n
  1. Do not short the terminals of a filter capacitor with a screwdriver. This can be dangerous.<\/li>\n
  2. Screw a 100-watt lightbulb into a socket with exposed leads.<\/li>\n
  3. Attach one lead to each terminal of the capacitor, the bulb should illuminate.<\/li>\n
  4. When the bulb turns off, the capacitor is empty.<\/li>\n
  5. Alternatively, you can bridge the terminals of the capacitor for a few seconds with a high wattage resistor, something like 2.2k ohms, 10 watts will work.<\/li>\n<\/ol>\n

    Switched-mode power supplies have multiple large-filter capacitors that can hold hazardous charges, even if the power supply hasn’t been used in days. These filter capacitors typically have values as high as 220uF\/250V and 330uF\/400V. You must discharge the capacitors before working on power supply circuits so you won\u2019t get shocked.<\/p>\n

    There are three different ways to discharge large filter capacitors in a power supply: with a screwdriver, the leads of a socketed 100 watt light bulb, and the leads of a high-wattage resistor.<\/p>\n

    Using a screwdriver to discharge the capacitor is not recommended because you can generate a spark and damage the printed circuit board or circuitry of the\u00a0power supply<\/a>. You can even blow the power section. Keep in mind that if you know a capacitor\u2019s stored voltage is relatively low, you can discharge it with a small screwdriver without undue risk.<\/p>\n

    If the capacitor is holding a heavier charge, discharging the capacitor can melt the screwdriver\u2019s tip as well as the copper of the printed circuit board. A heavy spark is especially dangerous: it can cause small bits of solder lead or copper to shoot from the circuit board, potentially injuring your eyes.<\/p>\n

    The second method involves placing the leads of a socketed 100 watt electric light bulb on the capacitor\u2019s lead and is used by technicians around the globe. The light bulb acts as an indicator, showing if the capacitor contains a charge. If there is a charge present the light bulb will illuminate and eventually turn off when the capacitor in the\u00a0switching power supply<\/a>\u00a0is discharged.<\/p>\n

    The last method consists of placing the leads of a high-wattage resistor on the capacitor\u2019s leads. You can use a 2.2k ohm ten-watt resistor to discharge high voltage capacitors in a switched-mode power supply. It is a very simple and effective process, taking mere seconds to completely discharge the capacitor.<\/p>\n

    There\u2019s really no reason to discharge a capacitor with a screwdriver when all you need is a light bulb or a resistor, so keep that in mind the next time you need to discharge capacitors in a switched-mode power supply.<\/p>\n","protected":false},"excerpt":{"rendered":"

    Here is a short tutorial on how to discharge the capacitors in a power supply so you can safely repair<\/p>\n","protected":false},"author":42,"featured_media":4569,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"colormag_page_layout":"default_layout","footnotes":""},"categories":[1,4],"tags":[],"class_list":["post-836","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-all-posts","category-power-supplies"],"yoast_head":"\nHow to Discharge Capacitors in a Switched-Mode Power Supply | Simply Smarter Circuitry Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"How to Discharge Capacitors in a Switched-Mode Power Supply | Simply Smarter Circuitry Blog\" \/>\n<meta property=\"og:description\" content=\"Here is a short tutorial on how to discharge the capacitors in a power supply so you can safely repair\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/\" \/>\n<meta property=\"og:site_name\" content=\"Simply Smarter Circuitry Blog\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/CircuitSpecialists\/\" \/>\n<meta property=\"article:published_time\" content=\"2014-04-22T18:10:45+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2021-02-12T20:46:32+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.circuitspecialists.com\/blog\/wp-content\/uploads\/2020\/05\/Capacitors.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"225\" \/>\n\t<meta property=\"og:image:height\" content=\"225\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"George\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@CircuitSpecial\" \/>\n<meta name=\"twitter:site\" content=\"@CircuitSpecial\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"George\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/\"},\"author\":{\"name\":\"George\",\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/#\/schema\/person\/414c9adb626f1f36fba73f3b4ae376ca\"},\"headline\":\"How to Discharge Capacitors in a Switched-Mode Power Supply\",\"datePublished\":\"2014-04-22T18:10:45+00:00\",\"dateModified\":\"2021-02-12T20:46:32+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/\"},\"wordCount\":460,\"commentCount\":5,\"publisher\":{\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/#organization\"},\"image\":{\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/www.circuitspecialists.com\/blog\/wp-content\/uploads\/2020\/05\/Capacitors.jpg\",\"articleSection\":[\"All Posts\",\"Power Supplies\"],\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/\",\"url\":\"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/\",\"name\":\"How to Discharge Capacitors in a Switched-Mode Power Supply | Simply Smarter Circuitry Blog\",\"isPartOf\":{\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/#primaryimage\"},\"image\":{\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/www.circuitspecialists.com\/blog\/wp-content\/uploads\/2020\/05\/Capacitors.jpg\",\"datePublished\":\"2014-04-22T18:10:45+00:00\",\"dateModified\":\"2021-02-12T20:46:32+00:00\",\"breadcrumb\":{\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/#primaryimage\",\"url\":\"https:\/\/www.circuitspecialists.com\/blog\/wp-content\/uploads\/2020\/05\/Capacitors.jpg\",\"contentUrl\":\"https:\/\/www.circuitspecialists.com\/blog\/wp-content\/uploads\/2020\/05\/Capacitors.jpg\",\"width\":225,\"height\":225},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/www.circuitspecialists.com\/blog\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"How to Discharge Capacitors in a Switched-Mode Power Supply\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/#website\",\"url\":\"https:\/\/www.circuitspecialists.com\/blog\/\",\"name\":\"Simply Smarter Circuitry Blog\",\"description\":\"How To's, Reviews, and Product News from Circuit Specialists HQ.\",\"publisher\":{\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/www.circuitspecialists.com\/blog\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/#organization\",\"name\":\"Circuit Specialists\",\"url\":\"https:\/\/www.circuitspecialists.com\/blog\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/#\/schema\/logo\/image\/\",\"url\":\"https:\/\/www.circuitspecialists.com\/blog\/wp-content\/uploads\/2016\/03\/csi.jpg\",\"contentUrl\":\"https:\/\/www.circuitspecialists.com\/blog\/wp-content\/uploads\/2016\/03\/csi.jpg\",\"width\":120,\"height\":120,\"caption\":\"Circuit Specialists\"},\"image\":{\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/#\/schema\/logo\/image\/\"},\"sameAs\":[\"https:\/\/www.facebook.com\/CircuitSpecialists\/\",\"https:\/\/x.com\/CircuitSpecial\",\"https:\/\/www.youtube.com\/channel\/UCG87WTqDKIqA704uqjumJgg\"]},{\"@type\":\"Person\",\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/#\/schema\/person\/414c9adb626f1f36fba73f3b4ae376ca\",\"name\":\"George\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.circuitspecialists.com\/blog\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/secure.gravatar.com\/avatar\/f7719440cadb3ea0bf4a1ef0c50b309a?s=96&r=g\",\"contentUrl\":\"https:\/\/secure.gravatar.com\/avatar\/f7719440cadb3ea0bf4a1ef0c50b309a?s=96&r=g\",\"caption\":\"George\"},\"description\":\"George Leger has a Masters in Electrical Engineering from Stanford University, worked in private industry pioneering surface-mount technology and in government research labs for twenty years, published several papers on surface-mount technology, co-authored papers published in national symposiums on accelerator technology, was past president of SMTA and an adjunct professor at the community college level, holds a patent, and is a certified microchip design partner, serving as a consultant to many companies developing electronic circuits.\",\"sameAs\":[\"https:\/\/www.circuitspecialists.com\/\"],\"url\":\"https:\/\/www.circuitspecialists.com\/blog\/author\/george\/\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"How to Discharge Capacitors in a Switched-Mode Power Supply | Simply Smarter Circuitry Blog","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/","og_locale":"en_US","og_type":"article","og_title":"How to Discharge Capacitors in a Switched-Mode Power Supply | Simply Smarter Circuitry Blog","og_description":"Here is a short tutorial on how to discharge the capacitors in a power supply so you can safely repair","og_url":"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/","og_site_name":"Simply Smarter Circuitry Blog","article_publisher":"https:\/\/www.facebook.com\/CircuitSpecialists\/","article_published_time":"2014-04-22T18:10:45+00:00","article_modified_time":"2021-02-12T20:46:32+00:00","og_image":[{"width":225,"height":225,"url":"https:\/\/www.circuitspecialists.com\/blog\/wp-content\/uploads\/2020\/05\/Capacitors.jpg","type":"image\/jpeg"}],"author":"George","twitter_card":"summary_large_image","twitter_creator":"@CircuitSpecial","twitter_site":"@CircuitSpecial","twitter_misc":{"Written by":"George","Est. reading time":"2 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/#article","isPartOf":{"@id":"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/"},"author":{"name":"George","@id":"https:\/\/www.circuitspecialists.com\/blog\/#\/schema\/person\/414c9adb626f1f36fba73f3b4ae376ca"},"headline":"How to Discharge Capacitors in a Switched-Mode Power Supply","datePublished":"2014-04-22T18:10:45+00:00","dateModified":"2021-02-12T20:46:32+00:00","mainEntityOfPage":{"@id":"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/"},"wordCount":460,"commentCount":5,"publisher":{"@id":"https:\/\/www.circuitspecialists.com\/blog\/#organization"},"image":{"@id":"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/#primaryimage"},"thumbnailUrl":"https:\/\/www.circuitspecialists.com\/blog\/wp-content\/uploads\/2020\/05\/Capacitors.jpg","articleSection":["All Posts","Power Supplies"],"inLanguage":"en-US","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/#respond"]}]},{"@type":"WebPage","@id":"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/","url":"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/","name":"How to Discharge Capacitors in a Switched-Mode Power Supply | Simply Smarter Circuitry Blog","isPartOf":{"@id":"https:\/\/www.circuitspecialists.com\/blog\/#website"},"primaryImageOfPage":{"@id":"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/#primaryimage"},"image":{"@id":"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/#primaryimage"},"thumbnailUrl":"https:\/\/www.circuitspecialists.com\/blog\/wp-content\/uploads\/2020\/05\/Capacitors.jpg","datePublished":"2014-04-22T18:10:45+00:00","dateModified":"2021-02-12T20:46:32+00:00","breadcrumb":{"@id":"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/#primaryimage","url":"https:\/\/www.circuitspecialists.com\/blog\/wp-content\/uploads\/2020\/05\/Capacitors.jpg","contentUrl":"https:\/\/www.circuitspecialists.com\/blog\/wp-content\/uploads\/2020\/05\/Capacitors.jpg","width":225,"height":225},{"@type":"BreadcrumbList","@id":"https:\/\/www.circuitspecialists.com\/blog\/discharge-capacitors-in-switch-mode-power-supplies\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.circuitspecialists.com\/blog\/"},{"@type":"ListItem","position":2,"name":"How to Discharge Capacitors in a Switched-Mode Power Supply"}]},{"@type":"WebSite","@id":"https:\/\/www.circuitspecialists.com\/blog\/#website","url":"https:\/\/www.circuitspecialists.com\/blog\/","name":"Simply Smarter Circuitry Blog","description":"How To's, Reviews, and Product News from Circuit Specialists HQ.","publisher":{"@id":"https:\/\/www.circuitspecialists.com\/blog\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.circuitspecialists.com\/blog\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/www.circuitspecialists.com\/blog\/#organization","name":"Circuit Specialists","url":"https:\/\/www.circuitspecialists.com\/blog\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.circuitspecialists.com\/blog\/#\/schema\/logo\/image\/","url":"https:\/\/www.circuitspecialists.com\/blog\/wp-content\/uploads\/2016\/03\/csi.jpg","contentUrl":"https:\/\/www.circuitspecialists.com\/blog\/wp-content\/uploads\/2016\/03\/csi.jpg","width":120,"height":120,"caption":"Circuit Specialists"},"image":{"@id":"https:\/\/www.circuitspecialists.com\/blog\/#\/schema\/logo\/image\/"},"sameAs":["https:\/\/www.facebook.com\/CircuitSpecialists\/","https:\/\/x.com\/CircuitSpecial","https:\/\/www.youtube.com\/channel\/UCG87WTqDKIqA704uqjumJgg"]},{"@type":"Person","@id":"https:\/\/www.circuitspecialists.com\/blog\/#\/schema\/person\/414c9adb626f1f36fba73f3b4ae376ca","name":"George","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.circuitspecialists.com\/blog\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/f7719440cadb3ea0bf4a1ef0c50b309a?s=96&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/f7719440cadb3ea0bf4a1ef0c50b309a?s=96&r=g","caption":"George"},"description":"George Leger has a Masters in Electrical Engineering from Stanford University, worked in private industry pioneering surface-mount technology and in government research labs for twenty years, published several papers on surface-mount technology, co-authored papers published in national symposiums on accelerator technology, was past president of SMTA and an adjunct professor at the community college level, holds a patent, and is a certified microchip design partner, serving as a consultant to many companies developing electronic circuits.","sameAs":["https:\/\/www.circuitspecialists.com\/"],"url":"https:\/\/www.circuitspecialists.com\/blog\/author\/george\/"}]}},"_links":{"self":[{"href":"https:\/\/www.circuitspecialists.com\/blog\/wp-json\/wp\/v2\/posts\/836","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.circuitspecialists.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.circuitspecialists.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.circuitspecialists.com\/blog\/wp-json\/wp\/v2\/users\/42"}],"replies":[{"embeddable":true,"href":"https:\/\/www.circuitspecialists.com\/blog\/wp-json\/wp\/v2\/comments?post=836"}],"version-history":[{"count":4,"href":"https:\/\/www.circuitspecialists.com\/blog\/wp-json\/wp\/v2\/posts\/836\/revisions"}],"predecessor-version":[{"id":5194,"href":"https:\/\/www.circuitspecialists.com\/blog\/wp-json\/wp\/v2\/posts\/836\/revisions\/5194"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.circuitspecialists.com\/blog\/wp-json\/wp\/v2\/media\/4569"}],"wp:attachment":[{"href":"https:\/\/www.circuitspecialists.com\/blog\/wp-json\/wp\/v2\/media?parent=836"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.circuitspecialists.com\/blog\/wp-json\/wp\/v2\/categories?post=836"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.circuitspecialists.com\/blog\/wp-json\/wp\/v2\/tags?post=836"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}