BP2 voltages slightly off (resolved)

[Paul Birkeland]

If 14 to the chassis is 22 ohms, that's OK. 

12 to ground being open means you have a loose connection.  This could be on either side of the black/white twisted pair of wires leaving the balance pot, on the balance pot itself, the selector switch, etc.

[grosen]

OK.   I hate to be so needy, but I'm stumped.  What is the path to chassis ground from 12? I've got rock solid continuity from 12 to terminal D on the selector switch, and rock solid continuity from terminal C to ground.  The problem is zero continuity from D to C (if I understand correctly).  I've got continuity on the other side, from A to B on the selector switch (70k ohm).  So that's the obvious point where the channels differ.   So where's the path from C to D supposed to be?  Any chance I damaged the selector switch?  Or am I confused about how the path to ground from 12 is meant to go? 

Thanks one more time for all the help,

Gideon

[Paul Birkeland]

Center the balance pot, then measure the resistance of the upper pair of terminals without the 33K resistors across them, then measure the lower pair of terminals without the resistors across them.  Compare those resistances and let me know what they are.

[grosen]

Problem solved.   I was getting no continuity between the two terminals on the top rung of the balance pot.  I cleaned them up, got continuity of around 50K on the top and bottom, and now  the resistances and voltages are exactly right.  Man, my hunches about where the problem was were completely wrong. Glad I asked. 

I owe you a beer ...

Gideon

 

[Paul Birkeland]

  Man, my hunches about where the problem was were completely wrong. Glad I asked. 

I'm glad you were open to listening, let us know if you hit any other snags along the way.

-PB

[grosen]

Just wanted to say thanks again.  The pre-amp is up and running and sounds ... fantastic.  There's always a honeymoon period with new gear, so I don't want to overdo it yet.  But the combination of sweetness and details is just what I had hoped for.  I have an original BeePre that was pretty microphonic: sounded really good, but there was always a bit of reverb.  With the new unit I can tap on the chassis and hear nothing at all. 

 

[Paul Birkeland]

I'm glad it all fell together in the end.

-PB