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Old '''epoxy-enclosed X-class filter capacitors''' used in mains filter circuits have a habit of failing. The problem is not Tektronix specific | Old '''epoxy-enclosed X-class filter capacitors''' used in mains filter circuits have a habit of failing. | ||
The problem is not Tektronix specific – a great variety of equipment from the 1970s to the 1990s such as computers, printers, stereos etc. are affected, typically those with switch-mode power supplies. | |||
[[File:Failed RIFA capacitors.jpg|thumb|right|350px]] | [[File:Failed RIFA capacitors.jpg|thumb|right|350px]] | ||
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The issue has jokingly been called "RIFA madness". As [[wikipedia:RIFA AB|RIFA AB]] was originally a Swedish manufacturer, [https://www.epanorama.net/blog/2023/04/14/warning-on-failing-rifa-capacitors/ one commentator] has called them ''the electronic version of [[wikipedia:Surströmming|Surströmming]]''. | The issue has jokingly been called "RIFA madness". As [[wikipedia:RIFA AB|RIFA AB]] was originally a Swedish manufacturer, [https://www.epanorama.net/blog/2023/04/14/warning-on-failing-rifa-capacitors/ one commentator] has called them ''the electronic version of [[wikipedia:Surströmming|Surströmming]]''. | ||
It is best to | It is best to proactively replace this type of capacitor with a modern equivalent of the appropriate rating and classification. | ||
==Links== | ==Links== | ||
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* [https://www.youtube.com/watch?v=SAlo8i4i8pg Schaffner filter in a Solartron 7150+ DMM] @ YouTube | * [https://www.youtube.com/watch?v=SAlo8i4i8pg Schaffner filter in a Solartron 7150+ DMM] @ YouTube | ||
* [https://hackaday.com/2023/04/01/why-do-rifa-capacitors-fail/ Why do RIFA Capacitors Fail?] by Jenny List @ hackaday.com | * [https://hackaday.com/2023/04/01/why-do-rifa-capacitors-fail/ Why do RIFA Capacitors Fail?] by Jenny List @ hackaday.com | ||
==Ratings== | |||
[[wikipedia:Capacitor types#Class X and Class Y capacitors|Class X and Class Y]] refers to safety certifications. | |||
Class X are for use where their failure would not present an electric shock risk but could result in a fire, such as a filter capacitor connected across the AC mains. Class Y are rated for use where their failure would present an electric shock risk, such as filter capacitors connected from the AC line to protective earth (PE). | |||
Various subclasses (X1, X2 ...) define peak service voltages. | |||
See e.g. https://electronics.stackexchange.com/questions/333029/what-is-an-xy-rated-safety-capacitor-exactly for more details. | |||
[[Category:Repair issues]] | [[Category:Repair issues]] | ||
[[Category:Capacitors]] | [[Category:Capacitors]] |