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Old 20th March 2013, 11:26 PM   #1771
Joachim Gerhard is offline Joachim Gerhard  Germany
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Hesener has now " repaired " a certain amout of boards that have being send to him by desperate builders. He told me in a private conversation that he got very good and fast to track the issues because basically every time the same mistakes show up.
When you get into trouble, ask him. If it gets a total disaster he may repair the boards if time permits. I can not speak for him though. To repair 600 boards is of cause impossible.
Read the fu... manual and try to make no stuffing mistakes.
Our friend in Brunei got really mad. I said : look if you have reversed something.
He said NO: Then he found that he had reversed ALL Leds because he has mis interpretted the lettering. And so it goes...
Do not drink alcohol the day before and THINK before you put something in. Then the chance is high that it works right away. The instructions get permanently updated if we find any new bugs.
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Old 20th March 2013, 11:26 PM   #1772
FdW is offline FdW  Netherlands
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Default NJF selection for the PSU

About some more reasons for a (not to bad) (but still) noisy PSU. Salas has found that it is possible that the PSU generates 20 up to 50 mV of white noise. This level of PSU contamination is not affecting the RIAA but we want perfection.

After some discussion, between Salas and me, it was thought that the J310 may be the cause of the problem. Back to the simulator, and the datasheet then, what I find is this, the J310 is used as a CCS of 1mA, for this it needs a Rgs of (about) 3Kohm, that implies a Vgs of 3Volts. The Vgs of the HexFet is (about) 4Volts, in this application. That leave about 1Volt margin on Vds of the J310, given production tolerances and specification spread between manufacturers, this may be not enough.

In case where the Vds margin is to low, the J310 will not be a constant current source, in these cases the PSU will not function optimal, and a higher than normal noise level will be present.

Now how to solve this? Easy! Use a NJF that shows a higher margin. For instance, the 2SK170 needs a Vgs off (about, according to simulation data) 360mVolt, and that leaves a margin of 3.6Volts. That would be enough, but the 2SK170 is something like unobtainium. That is where I started my hunt for a replacement NJF. If should be cheap, leave lots of margin, and easy to get.

I went to the Mouse site and searched for NJF’s that fit the bill, from this and other data I compiled the attached graphs, left to right 0 Sec to 10 Secs is equivalent to 0 to 10 Volt on V1. All NJF’s that are at 1mA constant current in 2Volts (e.g. 2 Secs) are wanted, NJF’s that show 1mA constant current in 3Volts (e.g. 3 Secs) are considered marginal (and the J310 is there, just, borderline).

From my graphs, the best, commercially available and cheap NJF is the J113, good choices are 2SK170, BF256A, BF245A, BF244A, J113, U309 and J309. If you want to propose others, then let me know, if applicable, I will add them to the graph

(I replaced the graph, the first one posted was incomplete, sorry)


These are the most important/relevant messages regarding PSU and Pre-Reg.
  1. Mpp #4375 PSU-pre-regulator.
  2. Mpp #4610 V2 Schemas UPS and Amp.
  3. Mpp #6506 CCS fine-tuning.
  4. Mpp #6462 PSU with my notes.
  5. Mpp #6809 Do not try to feed the CVS of the CCS of the shunt with a regulated power supply.
  6. Mpp #7127 More about transformer selection.
  7. Mpp #7635 Single and dual transformer wiring (also corrected drawing) (See also #7733).
  8. Mpp #7733 Grounding (PSU, RIAA and Player).
  9. Mpp #7810 35V PSU for the CroMagnon.
  10. Mpp #7830 The PSU explained.
  11. Mpp #8386 My resistor recommendation’s.
  12. My Paradise #56 PSU Noise.
  13. PradiseBuilders #13 Schema's and assembly guide.
  14. PradiseBuilders #155 Vdc input voltage minimum simulated.
  15. PradiseBuilders #970 PSU oscillates; posible solutions?
  16. PradiseBuilders #983 Compensating the PSU for oscillations.
  17. PradiseBuilders #1173 Fixing oscillations (up to #1182).
  18. PradiseBuilders #1322 Fuse .
  19. PradiseBuilders #1387 Updated Paradise R3 assembly guide (Also German).
  20. PradiseBuilders #1403 Capacitors bad vs good.
  21. PradiseBuilders #1593 PSU Power Transistor selection.
  22. PradiseBuilders #1644 PSU Output Impedance.
  23. PradiseBuilders #1680 PSU Power Supply Suppression Ratio(PSSR).
  24. PradiseBuilders #1772 NJF selection for the PSU.
Have a look at these and their following messages.
Attached Images
File Type: png NJF Vgs Sims.PNG (66.7 KB, 412 views)

Last edited by FdW; 20th March 2013 at 11:40 PM.
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Old 20th March 2013, 11:29 PM   #1773
Joachim Gerhard is offline Joachim Gerhard  Germany
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Thanks, another brick in the wall.
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Old 20th March 2013, 11:36 PM   #1774
Benedetto is offline Benedetto  Germany
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@J.G.;
nothing fooled yet.
But in some Friends builds, there are some
issues that make them think....
Like heat !

@Frans ;
ordinary 2sk170 are easy to get from an
ordinary german supplier named R.... for
~0.70€ each.
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Old 20th March 2013, 11:42 PM   #1775
FdW is offline FdW  Netherlands
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Quote:
Originally Posted by Benedetto View Post
@J.G.;
nothing fooled yet.
But in some Friends builds, there are some
issues that make them think....
Like heat !

@Frans ;
ordinary 2sk170 are easy to get from an
ordinary german supplier named R.... for
~0.70€ each.
Then I say, go for those, use a 330 Ohm Rgs and it will work fine. The J113 is 15 $ct (12 EuroCent) at Mouser and will work just as nice.
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Old 20th March 2013, 11:43 PM   #1776
Joachim Gerhard is offline Joachim Gerhard  Germany
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too much heat of the cooling fins ?
On the other hand running the cooling fins on lower heat would provoke a plethora of responses that a shunt works best driven HOT.
That comes from too much input voltage.
When the semis get hot there is a chance of oscillation.
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Old 20th March 2013, 11:47 PM   #1777
FdW is offline FdW  Netherlands
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We have seen PSU's that where oscillation, but not in such a way that they where excessively heating due to this. All oscillating PSU's, for as far as I have seen, did survive with no other damage then there (and my) pride
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Old 20th March 2013, 11:56 PM   #1778
FdW is offline FdW  Netherlands
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Quote:
Originally Posted by Joachim Gerhard View Post
too much heat of the cooling fins ?
On the other hand running the cooling fins on lower heat would provoke a plethora of responses that a shunt works best driven HOT.
That comes from too much input voltage.
When the semis get hot there is a chance of oscillation.
That all being true, we did establish that 26 Volts on the input of the PSU sets best performance, any thing more creates heat, and heat only (e.g. not performance, non what so ever, do not destroy more environment than strictly needed for proper HiFi).
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Old 21st March 2013, 12:00 AM   #1779
Joachim Gerhard is offline Joachim Gerhard  Germany
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I was not aware that i destroy my environment with my proper hifi (:
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Old 21st March 2013, 12:04 AM   #1780
FdW is offline FdW  Netherlands
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Quote:
Originally Posted by Joachim Gerhard View Post
I was not aware that i destroy my environment with my proper hifi (:
Ohhh ye.., especially if you run it on brown-kohl. And I run on natural gas, and or coal, and or Norwegian waterfall's, and some wind mill's, and a bit of Nuclear (but I like that very much ).

Last edited by FdW; 21st March 2013 at 12:07 AM.
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