Build report: The Phuncgnosis (help needed)

[cab42]

Hi list

I made this vero layout (see below) for Tim Escobedos Phuncgnosis which I posted a while ago in the layouts gallery.
Finally this weekend I had the time and parts to build. Even though it does "phunc" it also distorts quite badly.

Here's my observations following the outline of the "What to do.." sticky:

Schematic: http://www.geocities.com/tpe123/folkurban/fuzz/snippets.html
Layout: See below
Changes to the circuit. Added a 47K to avoid switch pop (framed in blue in the layout). This was suggested by jmusser in a handdrawn layout, he was so kind to send me. Thanks Jeff!
Parts substitutions: 5M resistor between pin 6 and 7 on the IC changed to 4.7M
What does it do (and what did I do):

I get a pretty nice wah sound in both "up" and "down" positions, but at the same time an ugly distortion, most pronounced on the lower strings.
It distorts no matter the position of the 1M pot.

I tried to trace the circuit with an audio probe and made the observation that I have clean sound up to and on the input pins of the IC (TL062), pin 3 and 6, but the signal is distorted on the output pins, pin 1 and 7.

The LED's only light up very dimly (public display of ignorance: Are they supposed to light up at all?  :oops: )

I tried to change the IC to a 4558, but it didn't change anything, except that the output was lower.

As Tatems has got similar results by using the layout (this thread), I'm afraid the problem is in the layout. I did find one error, but this doesn't change anything.

Voltages:

Battery: 9.05 V
Board:    9.05 V
Vr:       4.33 V

IC:
1: 4.59
2: 4.57
3: 1.10
4: 0.00
5: 4.33
6: 1.46
7: 4.53
8: 9.05

D1:
K: 0.00
A: 0.00

D2:
K: 0.00
A: 0.00

D3:
K: 2.65
A: 0.00

Any help or hints are appreciated.

Regards and thanks in advance

Carsten

The layout:

[cab42]

Bump!!!

Last chance to reply before I ditch the layout and starts all over!!


Carsten

[spudulike]

On that layout make sure D2 has its anode on row 3 and its cathode on row 2. Its badly labelled.

[cab42]

On that layout make sure D2 has its anode on row 3 and its cathode on row 2. Its badly labelled.

Thanks Spudulike,

It's correct that the layout is wrongly labelled, I'll fix that. However, when I just checked the circuit it looks as the the diode is mounted correctly.

But something must be wrong in that region of the layout as I get no voltage at all at D1 & D2 or....


Regards

Carsten

[jmusser]

I wish I had my circuit available to take voltages off of, but I'll be at work the next couple days, and staying with my Uncle. Your welcome for the schematic, but the anti-pop resistor I believe was Pete Moore's idea. I don't get distortion with mine, but it's built on perf board. I must be awful lucky, because I have yet to have noise related problems due to layout. I just basically follow the schematic for layout. In fact, (and I've said this before elsewhere) all my Tim Escobedo circuits have been incredibly noise free.

[j.frad]

Yeah I've got the same prublem with my nurse quacky and I wasn't able to get rid of it... I was strongly considering building the phuncgnosis to replace that bad quacker, but you juste made me doubt!

I'll let you all know how it turns out when i build it... I don't have any electronics retailer near me at the moment, figure how desperate i'm getting with that tremulus and all the others just waiting for me!can't wait to get back to building!!!

[cab42]

I wish I had my circuit available to take voltages off of, but I'll be at work the next couple days, and staying with my Uncle. Your welcome for the schematic, but the anti-pop resistor I believe was Pete Moore's idea. I don't get distortion with mine, but it's built on perf board. I must be awful lucky, because I have yet to have noise related problems due to layout. I just basically follow the schematic for layout. In fact, (and I've said this before elsewhere) all my Tim Escobedo circuits have been incredibly noise free.

I would be very greatfull  if you could take time reading voltages sometime when you get home.

In the next version I will also credit Pete for the anti-pop resistor.

I have just been through the schematic again checking all nodes and component orientations both on the layout and on circuit and everything seems to match.

If we assume (theoretically ) that my layout is correct, is there any other thing that could cause the distortion? E.g the ground trace and the vref trace being too close to each other?    

Regards

Carsten