Help with finishing SCA N72 kit-think it's fixed

[craigmorris74]

Hi,

Tim at SCA hasn't been able to answer my latest post today. Since I have time to work today, I thought I'd post my stats here and see what you guys thought.
I have tried plugging in a SM57, but I have to crank the input and output to get any signal, and of course then it is loaded with hiss.

Her are my V reading at the 6 resistors:
Q1 C-3.9 B-2.4 E-1.9
Q2 C-12.6 B-3.9 E-3.2
Q3 C-21.9 B-12.6 E. 12.0
Q4 C-5.3 B-.9 E-.3
Q5 C-21.4 B-5.6 E-5.0
Q6 C-21.4 B-5.0 E 4.4

I'm not great with a scope, but here's a pic I generated with as close as I could get to recommended settings. No clipping as in pics in directions, but a notch in the upsplope of the wave.
http://www.angelfire.com/ky3/craigorris74/sine.jpg

Any suggestions are welcome.
Thanks,

Craig

 

[broccoli]

okay... let's see if this is any help to you... i've built six of tim's kits and ran into problems on two of them... always minor things.... such as misplaced resitors or reversed regulators.... so, my suggestion is to go back to the schematic and double-check EVERYTHING. make sure every single thing is in it's correct place, your caps are observing the correct polarity, etc. it's the easiest mistake you could make. second would be to check for cold solder joints. third would be to check your work on that input tranny. that thing is a complete bitch to solder onto the board. fourth, make sure your Q6 transistor is installed the right way.... i know these are fairly obvious things to check for, but they're really easy to overlook when you're building something and can't wait to try it out. good luck!

joe

 

[craigmorris74]

Broccoli, you were right, just needed to double check everything. As I had a sneaky suspicion, the problem was with the input transformer. I didn't bridge pins 8 and 9 on the output as instructed. Did that and its passing a clear, loud, signal.

Thanks,

Craig

 

[broccoli]

congrats on your build. i absolutely love the n72. i use it on almost everything. i would use it on absolutely everything if i had more of them! have fun!

joe

 

[Category 5]

Here too. THe N72 isn't perfect for everything...but for those sources it works well on it is the absolute best out there IMO. Vocals through these moduels are quite splendid.

Shane