Debugging a Diamond Comp

[Dulouz]

Hey guys!

I built the Diamond Comp over at Sabrotone, but I'm not getting anything when engaged. I've been over the layout plenty of times to be 99% confident I have everything in the correct spots with no solder bridges and no (apparent) cold joints.

I poked around with an audio probe yesterday and traced the signal to Q3. I get clean audio at the base, but very sputtery and quiet at the emitter. I haven't been doing this long enough to know if that's normal or what.

Any suggestions?

Here's a link and the layout:

http://www.sabrotone.com/?p=1073

[IvIark]

I'd measure the DC voltages of all transistors and IC and post them on Harald's blog.  If someone there has built one you may get the correct working voltages from them, and then any deviation from those voltages in your build will give you a good idea where the problem is.

[Dulouz]

Thanks for the suggestion!

I found where someone posted the voltages from this build on FSB. I'm going to measure them today and see what I can find.

[Dulouz]

I posted at Sabrotone, but I thought I'd post this here as well in case anyone here has experience with this build. Hope that's ok!

Here are the working voltages I found at FSB:

C B E
Q1 8 4 3.3
Q2 3.3 1.1 0.5
Q3 8 3.1 2.6
Q4 2.6 1.1 0.5
Q5 6.7 0 0
Q6 6.7 0 0
Q7 7.5 0 0
Q8 8 4 3.6
Q9 7.5 0 0

Here are my voltages:

Transistor: C B E
Q1: 9.220, 0.380, 0.176

Q2: 0.176, 0.830, 0.177

Q3: 9.230, 0.000, 0.176

Q4: 0.176, 0.192, 0.168

Q5: 6.800, 0.000, 0.000

Q6: 6.800, 0.000, 0.000

Q7: 9.220, 1.300, 0.746

Q8: 0.190, 0.660, 0.000

[Dulouz]

Harald at Sabrotone put up some control voltages.

  Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9
C 8.21 3.48 8.19 0.48 6.92 6.92 6.67 8.20 ~25mV
B 4.13 1.11 1.13 1.07 0 0 0 4.13 0.71
E 3.48 0.46 0.48 0.42 0 0 0 3.51 0

        1 2 3 4 5 6 7 8
IC1 4.13 4.14 3.95 0 3.96 4.14 4.14 8.20
IC2 4.08 4.08 3.89 0 3.90 4.08 4.07 8.20

Any ideas?

Why would I get 0.00v at the Base of Q3 when he gets 1.13?