SOS: I've created a Monster, Need help

[Astronaurt]

Hey everybody!

So I decided to play Dr. Frankenstein and make a terrifying hodgepodge creation. It's fundamentally an Analog driven Octave generator / mixer, so in order to accomplish this I combined the Octavia Fuzz with Merlin's U-Boat. Links to schematics below:

Octavia: http://fuzzcentral.ssguitar.com/octavia/octavianpnschematic.gif
U-Boat: http://valvewizard.co.uk/uboat.pdf

I've built both of these effects separately before, so I figured I could slap them together in a more-or-less graceful way. Presently I'm having trouble with trouble shooting it, so I was looking for some assistance or guidance on where to look.

The main two differences between the schematics provided and my implementation is that 1) I have the signal tapped off of the output of U1A to feed the Octavia input as well as to a "Clean volume" pot, and 2) the output of the "Clean Volume" pot, the output of the Octavia, and the output of the Octave down side of the Circuit from U2:B through C9, are all mixed each through 10K resistors to the input of U2:A

At the moment, It passes the clean signal perfectly fine, but the Octave Up vanishes in the mix and the Octave Down side of the circuit is not octave-down'ing at all. For reference, here are the voltages I've read:

Supply Voltage Reads: 9.45

U-Boat Side
U1: TL072
1) 4.56
2) 4.56
3) 3.67
4) 0
5) 4.56
6) 4.56
7) 4.56
8 ) 9.45

U2: TL072
1) 4.14
2) 4.56
3) 4.56
4) 0
5) 4.56
6) 4.56
7) 4.56
8 ) 9.45

U3: TL072
1) 4.56
2) 4.56
3) 4.97
4) 0
5) 4.97
6) 4.97
7) 4.78
8 ) 9.45

Q2: J201

G) 3.26
S) 3.29
D)  4.14

U4: LM833
1) 8.93
2) 4.98
3) 4.98
4) 0
5) 4.78
6) 4.35
7) 8.93
8 ) 9.45

U5: CD4013
1) 9.45
2) 9.45
3) 0
4) 8.92
5) 0
6) 8.92
7) 0
8 ) 0
9) 9.45
10) 0
11) 9.45
12) 9.45
13) 2.53
14) 9.45

Octavia Side
Q1: 2N5087
C) 2.95
B) 3.71
E) 4.36

Q2: 2N4401
C) 9.45
B) 2.95
E) 2.38

Q3: 2N4401
C) 5.05
B) 2.38
E) 1.73

If it helps at all, I'll take a couple img's of the board and post them up in a reply shortly.

Basically I've been chasing my own tail with this project for a bit too long and so I thought I'd reach out. Any pointers are, of course, greatly appreciated! Thanks y'all, in the meantime, happy building~

[TejfolvonDanone]

> are all mixed each through 10K resistors to the input of U2:A
What exactly you mean by "mixed"? You just grabbed one 10K resistor for each input and tied to the + input of the op-amp?

[Astronaurt]

> are all mixed each through 10K resistors to the input of U2:A
What exactly you mean by "mixed"? You just grabbed one 10K resistor for each input and tied to the + input of the op-amp?

Yes. All their outputs are already buffered in some respect, so it seemed reasonable enough.

[TejfolvonDanone]

Reasonable.

U1 pin 3, U2 pin 1, U3 pin 3 and 7 seem a little bit weird to me. But i'm just guessing.

[Astronaurt]

Here's a couple images of the whole board from Top and Bottom views. I've got a couple more images ready, but I'll wait on those in case someone asks for a closer look or to thread bump it if they don't.

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[duck_arse]

Code Select Expand

U4: LM833
1) 8.93
2) 4.98
3) 4.98
4) 0
5) 4.78
6) 4.35
7) 8.93
8 ) 9.45

pin 1 and pin 7 voltages are way off what they should be. find out why.