File:Replacing 2SA798 dual transistor with two TO-92 single transistors ENG.svg
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Also applies to the 2sa979
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editDescriptionReplacing 2SA798 dual transistor with two TO-92 single transistors ENG.svg |
English: Many vintage Japanese hi-fi components (including the Optonica 2121H) contain the 2SA798 dual transistor with BCECB pinout. After 40-50 years these are likely to fail at random, and should be replaced whenever possible. There is no modern drop-in substitute, so a replacement is usually made of two generic PNP transistors in TO-92 package. There are hundreds of types available; as long as their rated voltage and current exceed 40V and 100mA of the 2SA798, and the beta is high enough, any well-matched pair will do. Matching is easy if you have something like twenty devices from the same factory batch - there will almost always be two or more very closely matched pairs. TO-92 transistors may have either CBE (e.g. BC556) or BCE (e.g. KSC922) pinout, but in either case mating two transistors is as easy as 1-2-3-4. More in the video [1]
Русский: В японской аппаратуре 1970-х (да и позже) годов часто применялась двухтранзисторная сборка 2SA798, на практике - по прошествии сорока лет - нередко выходящая из строя. Никакой замены в аналогичном корпусе с цоколевкой BCECB давно не производится. При восстановлении аппаратуры (да и просто профилактики ради) сборка заменяется на два дискретных транзистора в корпусе ТО-92. В зависимости от цоколевки транзисторов (в центре база либо в центре коллектор) применяются две конфигурации. Подбор пар - при наличии хотя бы двух десятков транзисторов из одной партии - сложности не составляет. Для выравнивания температур два транзистора склеиваются цианакрилом и одеваются в общую термоусадку. |
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Author | Retired electrician |
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current | 20:39, 21 February 2020 | ![]() | 930 × 340 (67 KB) | Retired electrician (talk | contribs) | {{Information |Description={{en|1=Many vintage Japanese hi-fi components (including the Optonica 2121H) contain the 2SA798 dual transistor with BCECB pinout. After 40-50 years these are prone for random failures and should be replaced whenever possible. There is no modern drop-in substitute, so a replacement is usually made of two generic PNP transistors in TO-92 package. There are hundreds of them available; as long as their rated voltage and current exceed 40V and 100mA of the 2SA798, and t... |
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Height | 96.012764mm |