death by audio robot vero- potentiometer swapped and acting freaky

[goldenmonkeycolor]

i built a death by audio robot from this layout

http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/DBA/01-DBA_ROBOT_VERO.png

I have a weird problem.  When I turn the volume control past about 10 oclock it takes a HUGE jump in volume, if i go just past that(at about noon) the volume cuts in and out and the circuit doesnt even really work.

I've tried swapping the pots- tried a linear pot (hey at least I tried), measured all the resistors.  Any other ideas where this problem could lie?

Also- it seems a bit muffled and bassy compared to the demoes I've heard of the original.  I'd like to fix that, but I didnt really notice any huge change switching the input cap and that 470pf cao.  Maybe i didnt try severe enough value changes?

Any help is greatly appreciated!
Thanks!

[peterg]

Try switching the wires to lugs 2 and 3 on the volume pot.

[goldenmonkeycolor]

Try switching the wires to lugs 2 and 3 on the volume pot.

2 and 3?

[goldenmonkeycolor]

ok.  i tried that.  still have the jump (seems even bigger now), but it also seems like the pregain control is behaving differently- like its not affecting the circuit as much as it did before the swap.

I really have no idea.

here's a link to the schematic
http://revolutiondeux.blogspot.com/2012/01/death-by-audio-robot.html

[goldenmonkeycolor]

it may be worth noting that the pre-gain control works backwards to a typical gain .  clockwise is least amount of gain.

[peterg]

For the gain control pins 3 and 2 should be connected. Typically the scheme shows pot pin 3 at the top.

I have no idea why DBA wires the the volume pot input to pin 2. Input should go to pin 3, output to pin 2 and pin one goes to ground. Are you wiring the pot correctly? With the shaft towards you and the pins pointing down pin 1 is the left one.

[goldenmonkeycolor]

sorry for the late reply, been working overtime.

Yeh I know my pot wiring.  I'm just wondering if the schematic is messed up.

so i should send the gain 3 wire on the vero layout to pins 2 and 3.  and send the row labelled gain 1&2 to just pin 1?

What else could cause this volume jump?  Could it be an issue with the robot chip?

also the pedal sounds kinda muffled compared to the video... ive tried changing a few caps but to no avail.  I was thinkg the 470pf 430k cap and resistor in parallel on the opamp.  maybe changing something about that more severely would help brighten it up a bit?

For the gain control pins 3 and 2 should be connected. Typically the scheme shows pot pin 3 at the top.

I have no idea why DBA wires the the volume pot input to pin 2. Input should go to pin 3, output to pin 2 and pin one goes to ground. Are you wiring the pot correctly? With the shaft towards you and the pins pointing down pin 1 is the left one.