First pedal build issues (Fuzz Face Clone)

[ArnauVB]

Hi! I'm new to this forum and to the diy pedal community!
I was just trying to build a Silicon NPN Fuzzface clone on my free time, but I keep beating my head against the wall. The problem I seem to have with the build is that there is no voltage drop on the 470 and 8,2k resistors that lead to the Collector of the second transistor of the circuit, so there's 9v (instead of 4,5-5 which I think are the standard ones). I've tried everything and checked the schematic a thousand times, but I can't seem to find what did I do wrong (I've checked continuity everywhere and I still get no sound when the pedal is on). The pedal works in bypass mode though. The guide I followed is the one on this website (the basic one): https://guitar.com/guides/diy-workshop/diy-workshop-build-your-own-fuzz-pedal/

Hope someone with more knowledge and experience on this matter can lend me a hand and excuse my english (I'm not a native speaker so it is a bit sloppy).

Best regards

Arnau

[PRR]

> Hi!

Welcome!

> I keep beating my head against the wall.

Don't dent wallboard. The landlord will take it out of your rent deposit. (How do I know??)

> no voltage drop on the 470 and 8,2k resistors that lead to the Collector of the second transistor

Forgetting to wire the 1k pot in Q2 Emitter is a very popular mistake.

[Kevin Mitchell]

Photos of your build would be very helpful.

But the two concerns I would have would be;
What transistors did you use? (PNP or NPN?)
What polarity did you wire the power supply?

[ArnauVB]

It is connected, I'll check if there's a cold joint but I don't think so...
Thx anyways, I'll report later when I get to check it.

[ArnauVB]

Photos of your build would be very helpful.

But the two concerns I would have would be;
What transistors did you use? (PNP or NPN?)
What polarity did you wire the power supply?

NPN transistors
Center negative power supply, supplying 9V to the joint of the 470 and 33k resistors.
I'll send pics of the build right away

[antonis]

You'll have to take a couple of DC measurents, like voltage on Q1 Collector, Q2 Emitter and on joint of 470R & 8k2 resistors..

P.S.
Welcome also..

[guywonder44]

Hi, Arnau. I just built that same pedal, but the tweaked version with the trim pots. I also just joined this forum because while mine works, my volume pot isn't working properly (instead of increasing linear from 0-500k, it goes 0-250k at 50% and then back to 0). Post a picture of your build and I'll see if I can spot anything. Did you build the tweaked version? Curious if you'll have the same problem.

Guy

[guywonder44]

Are you measuring the voltage drop between the ground and the collector of Q2? If so, try replacing the 8.2k with a higher resistor or a 10k or 20k trimpot. I ran into this with the germanium transistors I used and this fixed it.

[ArnauVB]

You'll have to take a couple of DC measurents, like voltage on Q1 Collector, Q2 Emitter and on joint of 470R & 8k2 resistors..

P.S.
Welcome also..

There is no voltage drop across the 8,2k and 470 ohm resistors
which indicates an open circuit, but there isn't one in theory.

q1:
e:0v
b:0,55v
c:1v

q2:
e:0,59v
b:1v
c:9v

[ArnauVB]

Feel free to ask for any more pics of the build if you think u can help!
Thx for the kind words everyone! I'm a bit clumsy posting so I won't thank you individually, but I aprecciate the support.

[duck_arse]

Arnau - try this. switch off power. set your meter to ohms range. put the black probe to the sleeve connection of one of your jacks - it should be ground. then put the red probe to the Q2 Emitter pin on the circuit board - you should read something between 1000R and 0R, as you turn the fuzz pot. is this the case?

also - your manners are bad when it comes to pot wiring. we generally don't solder to the bodies these days, and we use the lugs for the solders, not the holes for the rivets that hold the lugs. but we'll let you off this time, IF you get this pedal working.

[ArnauVB]

Arnau - try this. switch off power. set your meter to ohms range. put the black probe to the sleeve connection of one of your jacks - it should be ground. then put the red probe to the Q2 Emitter pin on the circuit board - you should read something between 1000R and 0R, as you turn the fuzz pot. is this the case?

also - your manners are bad when it comes to pot wiring. we generally don't solder to the bodies these days, and we use the lugs for the solders, not the holes for the rivets that hold the lugs. but we'll let you off this time, IF you get this pedal working.

Thx for the insight! Hope my writing manners make up for my lack of experience soldering pedals . I'll try to be cleaner on subsequent builds.

Regarding the measurement you told me to do, the multimeter displayed no reading when I checked resistance between Q2 Emitter and Ground, even though I moved the Volume pot as you requested.

Hope you can help me troubleshoot the project, it seems like you found somehing off with the build already

[antonis]

q2:
e:0,59v

the multimeter displayed no reading when I checked resistance between Q2 Emitter and Ground, even though I moved the Volume pot as you requested.

The above stetements are conflicting..
590mV should be the result from "some" current flowing through a resistor of "0.59/some" value..

[ArnauVB]

q2:
e:0,59v

the multimeter displayed no reading when I checked resistance between Q2 Emitter and Ground, even though I moved the Volume pot as you requested.

The above stetements are conflicting..
590mV should be the result from "some" current flowing through a resistor of "0.59/some" value..

The comment that suggested to measure resistance between Q2 emitter and ground said to check for a value between 0 and 1k ohm while I spun the volume knob, so the value between the Emitter and Ground must be greater than 1k (anyways i checked with the multimeter on all modes till 2M and it measured nothing).

[antonis]

If so, you have no continuity somewhere between Q2 Emitter, Fuzz pot and GND..
You measure 590mV at Q2 Emitter due to Q1 V_BE(550mV) + 40mV voltage drop on 100k feedback resistor due to Q1 Base current..

Focus on both sides of Fuzz pot joints..!!
Or at Fuzz pot itself (which seems to have a burned out track..)

[ArnauVB]

If so, you have no continuity somewhere between Q2 Emitter, Fuzz pot and GND..
You measure 590mV at Q2 Emitter due to Q1 V_BE(550mV) + 40mV voltage drop on 100k feedback resistor due to Q1 Base current..

Focus on both sides of Fuzz pot joints..!!
Or at Fuzz pot itself (which seems to have a burned out track..)

Ok! I'll check the continuity on the fuzz pot and I'll report back whatever I find!

If the pot has a burnt track as you say, should I just replace it?

Btw, do the rest ofthe transistor values look fine?

Sry for the lack of expertise, I'm really new to electronics (I'm majoring in Telecommunications but I just started this year)

[antonis]

If the pot has a burnt track as you say, should I just replace it?

Yes but DO NOT solder anything on its body..
You can check it by disconnecting either of its outer lugs and measure its body value on outer lugs..
If it's OK measure resistance between wiper and any other lug while rotating the shaft..

Btw, do the rest ofthe transistor values look fine?

Firstly fix Fuzz pot issue and then we'll come back for those..

[duck_arse]

Regarding the measurement you told me to do, the multimeter displayed no reading when I checked resistance between Q2 Emitter and Ground, even though I moved the Volume pot as you requested.

..... to measure resistance between Q2 emitter and ground ...... while I spun the volume knob, ......

Arnau - try this. ........  as you turn the fuzz pot. .....

no sir. volume pot is of no consequence in this inst, but the reading on E to ground is still valid, showing no connection somewhere in that line.

[antonis]

Stephen, I think OP actually refers on Fuzz pot..

[ArnauVB]

Don't worry guys! It was all just a matter of me soldering the pots very poorly due to my lack of experience. I replaced the damaged potentiometers and the fuzz worked like a charm!
I'll try to do some new builds this next week since I'm on vacation, thx for all the support on getting my first pedal to work!

PS: Does anyone have any tips on grounding to avoid noisy effects and such? (The fuzz is a bit noisy when I max both pots, but I think i did a good job)