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2SK97 dual N-channel JFET spec measurement & substitute

It is not likely that both input dual jfets fail at the same time. I suggest you retrieve your amplifier and either try to inspect it yourself, or have it revised by a trusted technician. I am afraid the techinician is not diagnisding your amp correctly. Most likely it is a matter of changing the fuse resistors, but i foubt the 2sk97 failed.
Edit:
Please start a new thread about your case and i am sure you will receive valuable advice in this forum.
 
Thank you for your advice and fast answer! Another technician also doubted that both 2sk97 failed. It is the first time, that I brought something there to be repaired, but they have a good reputation.
It will take a while till I can collect it and either try myself or bring it somewhere else. Sadly I have no experience repairing electronics. I can solder an have a multimeter but not more.
 
kamizoli said:
Sadly I have no experience repairing electronics. I can solder an have a multimeter but not more.
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And that is all you need for diagnosing. Download the pdf of the service manuals from hifi engine it is free after you register. Search in this forum for AU-517 and AU-717 and read threads about them to see how otger people worked on these models while you get your unit back.
 
dlucy said:
From their website, here is what the DCA75 and its software can do:

Curve Tracing - When connected to a PC using the supplied USB cable, a range of low current curve-tracing functions can be performed. Various graph types are available, with more to follow:
  • Bipolar transistor output characteristics, IC vs VCE.
  • Bipolar transistor gain characteristics, hFE vs VCE.
  • Bipolar transistor gain characteristics, hFE vs IC.
  • MOSFET and IGBT output function, ID vs VDS.
  • MOSFET and IGBT transfer function, ID vs VGS.
  • JFET output function, ID vs VDS.
  • JFET transfer function, ID vs VGS.
  • Voltage regulator, VOUT vs VIN.
  • Voltage regulator, IQ vs VIN.
  • PN junction I/V curves, forward and reverse options (for Zener diodes).
Curve tracing is performed using test parameters in the range of +/-12V, +/-12mA. All curve-tracing data can be instantly pasted into Excel© for further graphing and analysis. PC Software is included with the DCA Pro on a Peak USB memory stick. Software designed for Windows XP, Vista, 7, 8 and 10.​
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What can you tell me about these values for SK30 / SK68 4ea

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This year Texas Instruments launched a new series of low noise JFETs in SMD package that may be worth looking into. There has been already quite a lot of debate in the diyaudio forum. The JFE150 (single, N-channel) in 5 pins SOT-23 and a dual N-channel with independent sources and drains (JFE2140) in SOIC8.
There seems to be interest in TI in producing a P channel version but for the time being they are selling only N channel types. There are low noise, 40V Vgs and have an Idss in the 10-20 mA range, and transconductance close to that for a 2SK170GR or a 2SK389GR. See the linked dyiaudio thread for more discussion.
 
I need to replace the 2sk97 in my Sansui AU 717 because they are rusty and the pins fell off. From what I see, they recommend the lsk389b, but I can't get that one in my country. I was thinking of replacing it with two 2sk30a machet transistors or two 2sk117 transistors, but I'm not an expert on the subject and I would like to know what they say would be at least compatible.

necesito remplazar el 2sk97 de mi sansui au 717 ya que estan oxidados y se le cayeron los pines y por lo que veo recomiendan en lsk389b pero ese no lo consigo en mi pais estaba pensando remplazarlo con dos transistores en machet 2sk30a o dos transistores 2sk117 pero no soy experto en el tema y me gustaria saber que dicen seria almenos compatibles
 
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