Eros build - shunt regulator voltage test

[Anton]

Hello,
I am building Eros phono pre-amp. Really enjoying building it but faced a little problem...
I was doing shunt regulator voltage test today (as described at page 58 of Eros manual). When I powered up pre-amp - only three out of four LEDs on shunt regulator PC board did light up. The one in D1 slot at the A-side of the board didn't light up. What is the reason could be? I checked orientation of the LED - it is correct (silver end in the squared solder pad).
What should I do now? Try to re-solder this LED or replace it? Or may be the problem is in something else? I would appreciate your advise.

And another question: manual says voltage should stabilize at 225V. In my case when I connected to D1 tube socket terminal - voltage was 240 V (+6.6% difference), and when connected to D6 terminal - 221 V (-1.8% difference). Are these ranges considered to be acceptable?
Thank you very much!!!

 

[Grainger49]

Re-wetting the solder joints on the LED is the first step.

The voltage might be better if the LED is functioning properly.

 

[Anton]

Hello Grainger,
Thank you. I just tried to re-solder the LED and it  fell apart. I guess I damaged it somehow while soldering first time - may be applied too high temperature.
Now I need a replacement LED....

 

[Grainger49]

Contact the Queen and she will send you one out.  The contacts are on this page:

http://www.bottlehead.com/contu/cntu.html

 

[Anton]

Thanks Grainger - I sent her e-mail yesterday.

 

[Grainger49]

I shouldn't have spoken for Bottlehead, I don't work for them.  Past experience has shown that they are good guys, and a gal, and send parts that are damaged.  But "It's not for me to say."  (that is the name of a song from my teen aged years)

 

[Anton]

Granger,
I received LED replacement in the mail this weekend. Re-solder that one LED - now it works fine. All four LEDs lighting up now.
Voltage is 221.5 and 224.6 - very good.
Thank you for help.
And thank to Eileen for sending me extra LED.
Support is really superb.


Anton

 

[Grainger49]

Anton,

Give it a little time, 100 hours, to break in.  The tubes break in fine with no music going through them but the capacitors need an audio signal to break in.  

I bought a reverse (inverse) RIAA device for breaking in a phono stage.  I think it was from MCM Electronics but I can't find it today.  Hagerman sells one for $50, $30 for the half kit but then you need to order parts (12 resistors & 6 capacitors).  Both are completely passive, the accuracy is irrelevant and it allows you to feed it with a CD player on repeat and do a burn in.  Nothing but your CD player and Phono stage needs to be turned on.

Pretty neat.  But who builds a bunch of phono stages, except one poster I won't point fingers at.  He loves all of his.