Sounds good - but I`m really not sure where/what was wrong. Yes, I believe that the tech knows.
I am certain, that I want the caps replaced now.
I dont want to solder anything on the pre myself, no way
Dont have the guts! 
Thanks.
Normally, engineers are not allowed to talk to salespersons; but since I'm retired, I'll make an exception, just this once
That could be the 2N5566... Was the preamp silent before, and then this happened or has it been always like that? Anyway, you can replace them with LKS389 (dual) or matched LSK170 or matched 2SK170 if you can find the genuine ones.
That could be the cap's in the power supply frying. I would use the opportunity to replace all of the electrolytics; refer to the service manual, that'll be C1, C2, C7, C8 in the regulated power supply, and C1, C2 in the universal supply. Follow Nelson Pass's lead and use Elna Silmic if you can.
The 2 points above make me think your tech is not such a meatball after all, even though a long record of servicing B&O stuff is more a liability to me
These are the output transistors in the phono stage schematic and the high level schematic in the service manual.
And yes, you can do it, but first get some practice on some stuff you don't care about. You also need to invest in a good soldering iron, like the T12, about $50, and a good DVM, about $20 (do a search) plus some hand tools like pliers & screwdrivers.
Haha.. thanks
2N5566:
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*Edit:
I only had the pre for one month, and its been like this since I got it.
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Jon Soderberg said 2SK174 (as a pair) could be used? You mention 3 others, a bit confusing for me.
Are there differences in sound quality of those different types you think? What should I go with?
Okay, they will be changed..
what kind of caps can my used in the power supply as an upgrade or should I stick with it as "original"?
And what about those ERO mkt1813 - They are good as is?
Would be really nice to see a complete list of what should be upgraded/changed to make it "good" again.
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I don't know anything about a 2SK174. It could be a typo because the 2SK170 are often paired with their complementary 2SJ74.
I didn't dare to say this, but since this thread is not in Papaland yet, let me wisper in your ears: best is to remove them all together and put servo's instead.
Edit: too late, now I've offended Papa
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I don't know anything about a 2SK174. It could be a typo because the 2SK170 are often paired with their complementary 2SJ74.
I didn't dare to say this, but since this thread is not in Papaland yet, let me wisper in your ears: best is to remove them all together and put servo's instead.
Edit: too late, now I've offended Papa
Transistor:
AHA! Thats good to know.
So its 2SK170 then.
And I can switch the 2N5566 in the phonostage and use to replace the faulty one? and then use a pair of 2SK170 in the phonostage? (double post - already asked this to another helpful DIYaudio-fellow.. sorry)
Whats best to do?
Servo`s:
Is it just me.... he does not like servo`s.. (I dont even know what it is...
)FET's: I don't know. I used the 2N5566's in preamps long ago, so I'm familiar with them , but they haven't achieved cult status like the 2SK170/2SJ74. I'm building a FET-Tube cascode with 2SK146's, sort of giant 170's, so I'll know more this summer. Meanwhile, I'd rather fix the line stage with 2SK170 and leave the phono alone.
Servo's: simple concept: use opamp to null the output offset, so you don't need a coupling cap; a kind of DC feedback. Jeg tror ikke, Papa kan lide dem, so hush...
Servo's: simple concept: use opamp to null the output offset, so you don't need a coupling cap; a kind of DC feedback. Jeg tror ikke, Papa kan lide dem, so hush...
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When you look at the datasheet, the difference of the series is matching tolerance between the jfet pair, 2N5564 5mV, 2N5565 10mV and 2N5566 20mV which will contribute to an output offset of the FET9 measured before ouput coupling cap. Interfet makes the series with part number IFN556x and Mouser seem to stock the IFN5565 which should be perfectly usable. Mouser also have the IFN146 in stock which is a replacement for the 2SK146 mentioned by Zung.
However, you should be the one to decide what is best for you.
... Mouser also have the IFN146 in stock which is a replacement for the 2SK146 mentioned by Zung.
Thanks Indra, I wasn't aware of that, now they're in my shopping list and I have no more fear of frying my stash of 4 pcs. 2SJ146
.Has anybody tested them yet?
Edit: according to this, the IFN is slightly noisier at 3.5nV/SQRT(Hz) instead of 2.95, which doesn't bother me at all.
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On second thought, I'm less enthusiastic: looking closer at the InterFet site, I realize they make the IFN146-7 with their NJ450 process (attached), with which they also make the J108-09-10, but they don't show what's on the die. Investigating further National Semi did publish their die of the J110, made with their process 58 (attached). This die sets a big alarm!
More investigation: Scott Wurcer gave a talk at the 2013 Burning Amp where he showed the die of the Toshiba 2SK170 (attached): big difference! First, the number of cells is much bigger, and it appears Toshiba used interconnected individual cells, whereas NS use sort of "comb teeth" to achieve a large geometry.
Now even though the hard (dumb) numbers may (sort of) match on the spec sheets, I'm pretty sure there're sonic differences. Any opinions?
More investigation: Scott Wurcer gave a talk at the 2013 Burning Amp where he showed the die of the Toshiba 2SK170 (attached): big difference! First, the number of cells is much bigger, and it appears Toshiba used interconnected individual cells, whereas NS use sort of "comb teeth" to achieve a large geometry.
Now even though the hard (dumb) numbers may (sort of) match on the spec sheets, I'm pretty sure there're sonic differences. Any opinions?
Attachments
FET's: I don't know. I used the 2N5566's in preamps long ago, so I'm familiar with them , but they haven't achieved cult status like the 2SK170/2SJ74. I'm building a FET-Tube cascode with 2SK146's, sort of giant 170's, so I'll know more this summer. Meanwhile, I'd rather fix the line stage with 2SK170 and leave the phono alone.
Servo's: simple concept: use opamp to null the output offset, so you don't need a coupling cap; a kind of DC feedback. Jeg tror ikke, Papa kan lide dem, so hush...
Okay - might be the way to go then.
Mmm.. A little danish. Jeg tror du har ret. OP-amps, I heard stories... ;-)
When you look at the datasheet, the difference of the series is matching tolerance between the jfet pair, 2N5564 5mV, 2N5565 10mV and 2N5566 20mV which will contribute to an output offset of the FET9 measured before ouput coupling cap. Interfet makes the series with part number IFN556x and Mouser seem to stock the IFN5565 which should be perfectly usable. Mouser also have the IFN146 in stock which is a replacement for the 2SK146 mentioned by Zung.
However, you should be the one to decide what is best for you.
Just read Nelson`s post - "small stock of 2N5566" (mmm.. If I can get some
), which must seem as the HOLY GRAIL for me, that way keeping it more or less original, well, with the transistors that is. I still do think I would like to try different electrolytic caps, since they need an upgrade anyway.
Thanks
Good to hear.
Ohh boy ohh boy!
What does "DIP packages mean"?
Just googled... It`s in a rectangular housing instead of the can type?
The question is:
use 2SK170 (paired) or use 2N5566 (DIP package) (if possible to send to Denmark ofcourse)?
Now that you are here Nelson.
Since you are the one behind this golden piece of equipment, let me hear from you which electrolytic caps you would suggest for a complete makeover?
- You mentioned the ELNA Silmic "II"-(two?) - others same thing, so think I will stick with these for that part, unless some other magic caps exists?
- How about upgrading the powersupply? what needs to be done in this and which parts to upgrade, and to what?
Thank you for your reply!
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just replace all electrolytics
use decent ones - proper Tech knows which brands
regarding JFets - it's easy buying LSK170 here in Store
regarding bipolar transistors - generic ZTX and BC are absolutely adequate
again - proper Tech knows which types
and - do not touch anything else - replacing all elcos and just bad semiconductors is all what's needed
use decent ones - proper Tech knows which brands
regarding JFets - it's easy buying LSK170 here in Store
regarding bipolar transistors - generic ZTX and BC are absolutely adequate
again - proper Tech knows which types
and - do not touch anything else - replacing all elcos and just bad semiconductors is all what's needed
As I recall the critical caps in the circuit are film types that do not need
replacing. The rest can be good quality electrolytics.
Will tell the tech to use good ones, thank you.
Sounds good!
What is ZTX and BC?
Elcos`s = electrolytic caps then?
Thank you once again Zen Mod
From your pics, your preamp is fitted with the metal can TO-71. Replacing them with the plastic DIP will not be visually satisfactory. See attachment, the devices are circled in red.
The 2SK170/LSK170's also pose a small challenge in terms of aesthetics because the pinout is reversed: the 2N5566 is Source-Drain-Gate, whereas the 170's are Source-Gate-Drain, so 2 leads need to be twisted.
No big deal, really, but your preamp will not be "concours" ready.
The only good fit I can see is the LSK389: same can, same pinout, same spec's, possibly the same die (as the LSK170), but we need to wait for Papa's blessing.
The 2SK170/LSK170's also pose a small challenge in terms of aesthetics because the pinout is reversed: the 2N5566 is Source-Drain-Gate, whereas the 170's are Source-Gate-Drain, so 2 leads need to be twisted.
No big deal, really, but your preamp will not be "concours" ready.
The only good fit I can see is the LSK389: same can, same pinout, same spec's, possibly the same die (as the LSK170), but we need to wait for Papa's blessing.
Attachments
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