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Equivalent for 2SB557 & 2SD427 Complemetary Pair

Discussion in 'Audio' started by shrtrnd, Jul 9, 2019.

  1. shrtrnd

    shrtrnd

    3,670
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    Jan 15, 2010
    Replacing the audio output power transistors in a Pioneer SX-950 amplifier.
    There are too many disparate opinions out there on potential equivalents, and I am
    wondering if anyone here has an experienced opinion about what the best equivalent complementary
    pair for this apparently common audio amplifier configuration should be.
    There are 4 of each in the SX-950, and I'm having a hard time finding a supplier who actually still
    has 4 each of these obsolete power transistors.
    Thanks
     
  2. Bluejets

    Bluejets

    3,487
    706
    Oct 5, 2014
  3. shrtrnd

    shrtrnd

    3,670
    453
    Jan 15, 2010
    Thanks for finding them Bluejets.
    I imagine they are most likely genuine, and that's a great price.
    I know a lot of guys here who have found great deals from China.
    It may just be psychological with me, but I can't bring myself to buy China parts off eBay.
    I know, I know, darned near everything electronic is made in China nowadays, but
    there's no quality control from there, and no recourse if they don't work out.
    I'll still try to find equivalents, if I can't find the actual replacements someplace else besides China.
    I only want to have to replace these transistors once, with something I consider reliable.
     
  4. Bluejets

    Bluejets

    3,487
    706
    Oct 5, 2014
  5. shrtrnd

    shrtrnd

    3,670
    453
    Jan 15, 2010
    Alright, I'll see what can be done.
    My experience with Chinese vendors is that they DO have a lot of actual original manufacturer parts that they bought cheap when 'nobody' else wanted them, stockpiling vast quantities of those components for resale like they're doing now. Unfortunately, because they don't really have any oversight, I've seen a large number of counterfeits that usually work when you receive them, but fail long before they're supposed to, or just don't meet specs. Entrepreneurial enterprise as profit presents itself. My work involves troubleshooting and repair of a lot of high-end test and measurement gear from many different vendors. For a while some of those vendors paid a lot of money to specialty businesses that checked authenticity of supplied parts from China, to verify (at great expense) random lots of parts from China to check the specs, actually getting-down to X-Ray and destructive tests. Due to the large number of counterfeits discovered, the people I deal with now actually ban any parts from China being installed in their equipment.
    And yes, I've personally encountered equipment failures due to counterfeits.
    Probably something as cheap as the Toshiba parts you first found would not be worth the effort to counterfeit, but this is my own amplifier, and I would like to do the repair right the first time, once. I suppose it's just personal preference.
    Thanks again for finding these transistors that I asked about.
     
  6. techforce

    techforce

    7
    0
    Dec 26, 2008
    2SB557 subs to an NTE281 or NTE285 while 2SD427 subs to an NTE280. I recently had a similar problem with some obsolete NEC original pre-amp transistors for a stereo repair, and discovered that NTE does supply matched pairs with the "MCP" suffix at the end of the NTE number. The ones you need are power output, so probably they are not offered like that. Worse comes to worse if you have a curve tracer you can just buy some and match the closest ones to your spec.
     
  7. shrtrnd

    shrtrnd

    3,670
    453
    Jan 15, 2010
    Thanks for the heads-up on this techforce.
    Kind of annoying that once-popular components, that you see in a lot of equipment, become 'obsolete', and you have to hunt for 'equivalents' when they are no longer made.
     
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