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Rinat

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  1. It seems that current is limited to 0.20 ma. Look at the voltage across the 50k R12 resistor. It is 10v - Vbe(0v min). 10/50000 = 0.00020. So, it looks like 2sc3675 will work perfectly here.
  2. I've asked @ibuskiin PM and no - I've bought these transistors from another and more reliable source, the current official dealer of Onsemi. I've measured them with DY294 and tried to build curves up to 750v. Everything is ok. I've got them in a factory package with stamps, date codes, etc. Before I've made a payment they said that these transistors have some discoloration due to long storage. But actually, they look better than the ones I got from bdent.com 🙃
  3. Ok, thanks. I'll calculate if the replacement could be done.
  4. I feel for you and could only imagine how it feels to see such a lightshow ( 4. I would check if everything is ok with Q24/Q25, just in case. And a question about your version of PSU: could I replace KSC5026 with 2SC3675 ? I have hundreds of the latter. And there is nowhere to buy the first ones(. I did not make calculations yet.
  5. Thanks again, I am going to buy this DE-5000. I've heard many times that it's accuracy in a lucky cases can be better than in specs. It gives a hope 🙂
  6. @jamesmking, thanks for another awesome post. I remember that you made resistors/capacitors selection to reduce the tolerance. Did you use a LCR meter ? And which one ?
  7. Yea, I've bought a few parts for T2 from arrow. They have not a great customer support for individuals, but all parts are genuine.
  8. Thermal resistance 100k/w instead 80k/w..... I think it can be used, but I would make an accurate calculations before. And you will need a board with a full metal polygon and a way to mount it on heatsink. It is gonna to be cumbersome. Anyway I can't find IXCY too.
  9. Lower capacitance is better. And in this context I want to ask another question to all: I want to use AlN thermal pads for the transistors with 1mm thikness instead 1.6mm AlO. It adds a few picofarads to a capacitance between a metal tab and the ground. Is it ok ?
  10. I have a bunch of 2sk214 from bdent and their Vbr is measured as 220-240v by DY294. This is sudden for me, because I have the same result with 2sk216s. But I still afraid to use them as a replacenment because in other conditions, like temperature, Vbr could be lower than it was measured by DY294. But maybe I'm just too scared to burn something expensive 🙂
  11. I know a man who replaced EL34 by KT77 successfully, with slighly changed sound. These tubes was not from JJ and I know that JJ's KT-77 are not suited for T2. I would'nt be so adamant as Kevin - In my opinion you can change anything, but only with a really careful recalculation of the scheme. If you are not sure that you can handle it yourself, don't do it. I am going to try 6N23P-EV, but only because it is a direct replacenment for 6922 and I've measured every tube with good results. And am going to check all again, maybe even twice.
  12. I've measured 62s of mine 2sa1413 from bdent: https://docs.google.com/spreadsheets/d/1sadOLdhxStUQfL94wJkuKEtn7qOEWFBdP0m-BNzwVw0/edit?usp=sharing It is interesting that green transistors were worse than black. And thanks to Helium - I've found that 2sa1413 has a twisted pinout - BCE instead of ECB for 2sa1486.
  13. Oh, I thought that TO-251 = D-PAK. Thanks
  14. They have 25 pcs in stock, while the original scheme requires 26 pcs ) Personally, I would suggest to use 2sa1413-z if one wants to strictly follow the original scheme: it is the same transistor in TO-252 case (bdent says that it is D-PAK, but they have sent to me TO-252 version, which is even better for me). https://www.renesas.com/us/en/document/dst/2sa1413-z-data-sheet?language=ja But I think that STN9360 is even better option than 1486/1413....
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