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Hey Jeremy,
Just out of curiosity which way did it work? Up (wah) or down (yeow)? This may be a solution to my problem.....
Thanks

Latest attempt:
I replaced R12 thru R21 and C1, C9, C4 & C12. No change.... 
That covers just about all the components on the driver side of the Vactrols.

I don't believe it is in the power supply or the sensor side of the circuit because it works in the down position.
At this point I'm thinking it's the board itself although I can't see anything obvious with it......
Any other ideas???
Thanks!

Next steps:
I replaced C10 with one I tested to ensure it was working = no change
I removed the Range switch and tested it = it's fine.
I replaced the Range switch with jumpers and got the same behavior I've had all along in both positions.

I then opened the jumpers and inserted a 1M pot between R5 and Pin 5 of IC2B (Pins 2 & 3 of Range A switch on the schematic). By adjusting this pot I can get the unit to give a mediocre Up (autowah) sound. However it does not seem as sensitive as the typical Down position sounds.

I also have significant high hash noise when the Mode switch is in the HP position. This may be the issue you mentioned Rob, but using an audio probe I couldn't figure out where it was coming from. Basically the input pad is good, C2, C3, IC1_A1, R2, R3, all are noisy. Do you think it could be the Gain pot? It sounds fine when I touch each leg so I don't don't understand what's going on with this. I also don't understand why I can't hear audio when touching either leg of C1 but get audio after it......  Am I not using the audio probe correctly? Can one of you that have a working unit try this and let me know what you find?

Any help is appreciated......   Thanks again!

Thanks Matt for pulling all this together.

Okay, here's measurements with switches in LP/Up/Hi and pots at about 12 noon:
IC2_B 4   -7.76
IC2_B 5   2.65
IC2_B 6   2.65
IC2_B 7   4.48
IC2_B 8   8.36
VACT_1A (a)   4.48
VACT_1A (c)   2.71
VACT_2A (a)   4.49
VACT_2A (c)   2.70

When I pluck a bass string the voltage at IC2_B 7 and both VACT anodes (square pads marked + on the schematic)  goes up to about 6.3 then decays. So the main differences are that I have significant voltages at my IC2 B 5, 6 which the other builds don't and mine is not producing the same voltage change with an input signal.

This still makes me think that there's a problem with the circuit supplying (or controlling) IC2. Will look at this more today or tomorrow.
Thanks again guys.

Thanks for all the input guys. I'm still not getting anywhere new with mine. I replaced the 2 tants (C1 and C9) with bipolar electrolytics, and I don't think it sounds as good, but maybe that's just frustration clouding my hearing. 

Rob I hope your feeling better.
Mike your's sounds great and looks good too!
Let us know how your build goes Matt.

Thanks again all.

Okay, # 2 first: I measured the range switch in situ with my ohmmeter and it appears to be working properly. There is no direct connection to ground and the pins show the correct connections when switched.

Cathode of D2 shows voltage sweeps in both switch positions. I also swapped the IC TL072s and D2 shows the same for all 3 different IC TL072s  in all 3 IC sockets. Also pin 7 of all 3 ICs show voltage swings at all times whereas pins 5 & 6 only show voltage swings with the Range switch in the Up position. Based on this data it appears to me that all 3 IC TL072s are working, at least all 3 are the same.

With the Range switch in the Up position I am now able to hear some 'wahing' with full range signal but it is very slight and only in the upper treble range (above about 2K Hz, which is why I couldn't hear it previously when testing with my bass). With the Range switch in the Down position the effect is very noticeable and can be adjusted from low through higher frequencies with the mode and Hi/Lo switch, which I consider normal. If this was the effect I wanted I would stop here and box it up but the Up effect (basically an autowah for my bass) is what I'm really looking for.

Any ideas on how I can get the effect down to lower frequencies with the Range switch in the Up position? Based on observation of the LED the voltage appears too high because it never goes off. Is there a mod to the circuit which would affect this?

Thanks again for all your help. I have been working on this build on and off since November so any progress is good at this point.......

Here are 2 sets of measured voltages with no input to the pedal. The first is with the 11V supply:
Range switch Down
Vactrol 1
Anode 5.1
Cathode 3.3

Vactrol 2
Anode 5.1
Cathode 3.4

LED
Anode 1.71
Cathode 0

With Range switch Up
Vactrol 1
Anode 4.1
Cathode 2.3

Vactrol 2
Anode 4.1
Cathode 2.3

LED
Anode 1.65
Cathode 0

Using my regulated 9 V supply:
Range switch Down
Vactrol 1
Anode 2.8
Cathode 1.0

Vactrol 2
Anode 2.8
Cathode 1.0

LED
Anode 1.38
Cathode 0

With Range switch Up
Vactrol 1
Anode 4.2
Cathode 2.4

Vactrol 2
Anode 4.2
Cathode 2.4

LED
Anode 1.67
Cathode 0

All of these change a lot with music from my MP3 player into the pedal.  Vactrol anode voltages swing between -5 to +5 with the Range switch Down but are pegged at 6.4 with the Range switch Up.

Thanks for any further assistance or ideas.

Thanks mgwhit!
Changing the resistor did fix the sweep and peak controls. They both work really well now.

Still have the issue with only the 'Down' switch working. The 'Up' is a little better but still has too much voltage so it's basically almost full open even with the Gain pot at minimum.

I tried a regulated power supply at 9 volts and it is about the same, but the 'Down' does not work as well. The range of sweep and the sensitivity are limited. The indicator LED does not come on at all in the 'Down' position but is still on all the time in the 'Up' position.

Input is now V=8.96:
(omitted all zeros to make the list shorter)
IC 1   
4 -7.8
8 8.4

IC 2
1 1.7
4 -7.8
5 2.9
6 2.8
7 4.4
8 8.4

IC 3
4 -7.8
8 8.4

IC 4   
1 1.4
2 4.6
4 -3.6
5 -7.8
6 2.5
7 1.4
8 8.4

With the range switch in the up position only IC 2 changes to these:
IC 2
1 4
4 -7.8
5 3.3
6 3.4
7 2.5
8 8.4

I'm looking into the supply for IC 2 and checking my values and soldering again.

Looking forward to any other suggestions the group might have.
Thanks again!

Yes you're absolutely right. Even though I checked it twice (I saw what I wanted to see!) R6 is 390R not 390K. Will swap them and let you know what happens.

Thanks!

Confirming that I do have -10.4 V at -ve pin on C14.

Thanks for your replies. I feel like a dope - obviously supply voltages should be the same for all the IC's.  Let me try again - I have remeasured them and they are similar to RobA's:

IC 1   
1 0
2 0
3 0
4 -10.5
5 0
6 0
7 0
8 11.0

IC 2
1 3.5
2 0
3 0
4 -10.5
5 4.4
6 4.4
7 4.5
8 11.0

IC 3
1 0
2 0
3 0
4 -10.5
5 0
6 0
7 0
8 11.0

IC 4   
1 1.4
2 6.0
3 0
4 -4.8
5 -10.6
6 2.5
7 1.4
8 11.0
                        
           Inputs   Outputs               
VACT 1   4.4   2.7   0   0            
VACT 2   4.6   2.8   0   0   

I had to substitute C1 and C9 with tantalum, and C4 is a large cross-over cap so I had to lay it down to fit it in the box. I replaced C13 because I thought it was bad but I still have the same issues. Pictures attached.

The pedal works as expected with the Range switch 'Down' but not with it 'Up'. The voltage to the Vactrols appears to be too high because the LED is lit even with the gain control at minimum, but I can't read the schematic well enough to figure out why........

I made an audio probe and listened to many different points tonight but nothing really makes sense to me. Anything on IC 2 sounds very distorted, but inputs and outputs from the board are fine.

Thanks again!

Newbe here.... This is my second build

I have a partially working unit. It does 'yeow' (or down) but does not 'wha' (or up) and the peak pot has no effect. I assume that if the effect partially works, the Hi/Lo & LP/BP/HP switches work and the gain & volume pots work that the wiring is OK. The Peak pot itself appears to work based on measuring it in the circuit.

I have done the following:
Checked are rechecked components and values - OK
Reflowed the solder

Following are voltages measured with the effect bypassed and input V=11.7:
   1   2   3   4   5   6   7   8
IC 1   3.3   3.3   1.5   0.7   5.2   6.2   2   11.2
IC 2   2.1   1.7   1.6   0.7   4.5   4.2   8.6   11.2
IC 3   10.2   0   0   0.7   0   4.8   10.4   11.2
IC 4   1.4   6.1   0   -4.8   -10.6   2.5   3.7   11.2
                        
   Inputs      Outputs               
VACT 1   8.6   6.8   0   2            
VACT 2   8.6   6.8   4.9   10.2            

I am concerned about the output of VACT 1 being so low. Could it be bad or could it be a problem in the circuit after it?
Any other suggestions/ideas welcome.
Thanks.....