Fuzz pedal oddities...

[simo2guit]

Hi there. I've just (about) finished a fuzz pedal build but have had some problems and am trying to debug. The pedal I built is based off the Axis Face Silicon Schematics. While the signal goes through when in standby, there is no sound once it is switched to the circuit. The led is going on ok, but the weird thing is that I accidentally discovered that if I touch the tips of the output and input together I get fuzz!! I have been staring at it for hours but can't understand what I have done wrong or why directly connecting the input and output seems to get the circuit working?

Here's how the 3PDT switch is wired.

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1: input to circuit
2: output from circuit
3: +9v for led
4: input from guitar
5: output to amp
6: 1k resistor to led to ground
7 and 8 are tied together and 9 is empty

Again.. the only way to get the fuzz to sound is to jumper 4 and 5.. but I don't see why this works or if it is safe to just jumper them. It makes it seem as though the circuit input and output are the wrong way around, but I'm am certain they are not.

If any gurus have any ideas that a noob like me could miss, I would greatly appreciate it. Thanks for reading all this.

Simon

BTW: I was going to post pics but my camera battery died.. so will post pics in a few hours.

[SonicVI]

Do you have the swith oriented the correct way? ie: looking at the lugs they should be horizontal rather than vertical

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[petemoore]

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 I once made the mistake and completely wired a 3pdt 1/4 turn to the left or right from oriented properly [what sonic refers to^], test with the DMM how the signal path flows through...electromechanical devices, wires etc.
 Or use audio probe or audio injector to do the same.
 Only on low voltage circuits, the output signal path can be heard with the 'thumbuzz' technique [I hold personal patent on...lol], use a screwdriver to connect your thumb to the output [which goes to live amp input]..you should hear the 'thumbuzz', follow that through the output cable tip, output jack tip, output jack tip lug, wire...is supposed to go through the switch [still sounding the same] goes to then through the volume cotnrol [if turned all the way up the VC pot's input should sound the same as it's output-wiper], then across the circuits output capacitor [should be about the same, maybe slight bass rolloff], then try the base of Q2, you should hear a boost, base of Q1 should be seriously boosted.
 I've fixed countless miswires using the simple thumbuzz method...all the way from the output cable tip to through bypass, through circuit...to the input jack and cable tip. [easier even than the audio probe method] or you could use an 'audio injector' [tape a key down on a childs electronic keyboard set to organ, adjust volume and use the output as a source] instead of the thumbuzz injector.

1: input to circuit
2: output from circuit
3: +9v for led
4: input from guitar
5: output to amp
6: 1k resistor to led to ground
7 and 8 are tied together and 9 is empty

[simo2guit]

I'm trying to add pics but can't seem to figure it out... not may day I guess. Any help is appreciated.

[solderman]

I'm trying to add pics but can't seem to figure it out... not may day I guess. Any help is appreciated.

See
http://solderman.fatabur.se/Purple%20Haze/Purple%20Haze%20Layout.pdf

You are looking on  the stomp switch from above mirror the image to get a bottom view

//Solderman

[petemoore]

  Think of the 3pdt as three, separate but simultaneously activated SPDT's.
  Find one 'column'...one SPDT section, first.
  there are three 'columns' and three 'rows' [9pins].
  As you look down on the pins, you may have to turn the switch 1/4 turn so the columns are up/down.
  Each of the '3' in 3pdt, is a 'pdt' [one pole, two throws]
  And connects like this:
  Throw------Pole      Throw
  Hit the switch one tima and connects like this:
  Throw       Pole-----Throw
  Pick one of the three poles, and connect it to an input jack tip.
  Picka another pole and connect it to the output jack tip.
  [find the pole/throw connection using the DMM first]...or...look through the 'needle eyelets'...looking through 3 holes [they're inline...looking from the side of the switch]...you're looking through a throw, pole, throw...
  Once you check that a pole lug of the switch, assigned to input jack tip, switches between the throw lugs which connect to either the bypass jumper or the circuit input wire, the switch is oriented correctly and you can follow the layout.
  SPDT:
  Throw
  Pole
  Throw
  DPDT
  Throw     Throw
  Pole         Pole
  Throw     Throw
  3PDT
  T            T              T
  P [input  P [output   P [LEd?
  T            T               T
  Make sure the P [input...connects to the input jack, and either the T above it, or the T below it [depending on switch position].
  Has nothing to do with correct connections, but I usually run the LED in the middle on high gain pedals to help separate the input and output.
 

[simo2guit]

Hey guys,

Thanks for all your help. I managed to find a spot in the circuit board that I meant to solder and never did lol javascript:void(0);. Thanks a lot for the thumbbuzz technique... it worked great. So the fuzz is working and sounds very cool, but it seems like the volume is way too low.. even with the level at max, it is quieter than when bypassed... In the schematics I used, I already changed out the common 330 ohm resistor with a 1k2 which is supposed to help boost the volume. Do you think I should just keep increasing the size of this resistor, or is there a better trick to getting more output from the circuit??Also,  I am using a 100k audio taper pot for the level as recommended by the site I got the schematic/layout from maybe its not letting me crank it loud enough?

Thanks in advance

BTW can you just post pics here as an attachment or do I need to host it elsewhere?

[solderman]

Hey guys,

Thanks for all your help. I managed to find a spot in the circuit board that I meant to solder and never did lol javascript:void(0);. Thanks a lot for the thumbbuzz technique... it worked great. So the fuzz is working and sounds very cool, but it seems like the volume is way too low.. even with the level at max, it is quieter than when bypassed... In the schematics I used, I already changed out the common 330 ohm resistor with a 1k2 which is supposed to help boost the volume. Do you think I should just keep increasing the size of this resistor, or is there a better trick to getting more output from the circuit??Also,  I am using a 100k audio taper pot for the level as recommended by the site I got the schematic/layout from maybe its not letting me crank it loud enough?

Thanks in advance

BTW can you just post pics here as an attachment or do I need to host it elsewhere?

No you need to upload them and link to them. But you can upload them to http://www.aronnelson.com/gallery/main.php
Se the link on the top of this site. And link by using the "picture" button
//Solderman

[Greg M.]

123
456
789
 I once made the mistake and completely wired a 3pdt 1/4 turn to the left or right from oriented properly [what sonic refers to^], test with the DMM how the signal path flows through...electromechanical devices, wires etc.
 Or use audio probe or audio injector to do the same.
 Only on low voltage circuits, the output signal path can be heard with the 'thumbuzz' technique [I hold personal patent on...lol], use a screwdriver to connect your thumb to the output [which goes to live amp input]..you should hear the 'thumbuzz', follow that through the output cable tip, output jack tip, output jack tip lug, wire...is supposed to go through the switch [still sounding the same] goes to then through the volume cotnrol [if turned all the way up the VC pot's input should sound the same as it's output-wiper], then across the circuits output capacitor [should be about the same, maybe slight bass rolloff], then try the base of Q2, you should hear a boost, base of Q1 should be seriously boosted.
 I've fixed countless miswires using the simple thumbuzz method...all the way from the output cable tip to through bypass, through circuit...to the input jack and cable tip. [easier even than the audio probe method] or you could use an 'audio injector' [tape a key down on a childs electronic keyboard set to organ, adjust volume and use the output as a source] instead of the thumbuzz injector.

1: input to circuit
2: output from circuit
3: +9v for led
4: input from guitar
5: output to amp
6: 1k resistor to led to ground
7 and 8 are tied together and 9 is empty

I know this one is fairly old but I have searched through the site for Axis Face Si problems and this one is the only one that helped me at all, mostly because of the Thumbuzz method here.

I have built the Axis Face Si and am getting no signal even when bypassed.  I used the thumbuzz method and got the boost from Q2 base and outrageous boost from Q1 base as you mention.  Also get loud buzz at point 2 (Bias 2) but not much from the Attack pot at all.  Does this mean anything notable?  Also no real hum from either of the electrolytic caps or either side of the diode.

Any ideas or suggestions would be greatly appreciated. 

[BoxOfSnoo]

You should probably create a new thread, otherwise you won't get a lot of eyeballs...  Here's another one: http://www.diystompboxes.com/smfforum/index.php?topic=39942

But you'd like to know the voltages on a working one... I measured mine and got these

Q1 (MPS 2222a)
C: 1.265
B: .569
E: 0

Q2 (2N3904)
C: 4.5ish (controlled by the trimpot)
B: 1.265
E: .629

But I think you need to investigate your bypass, why it's not working.  You really should have a direct connection between tip to tip just through the switch as described above, and a common ground path between jack sleeves.