Home Forums GuitarPCB Build Support First Time Build Help – One Knob Fuzz (solved)

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    Andrew Page

    Hello All… first time builder, first time caller, er… poster. Anyhow, have been interested in guitar pedals for a while but have little to no experience with electronics. So thought maybe the best build to start would be the One Knob Fuzz kit from Pedal Parts And Kits. The page indicated that it was a good one for beginners, which apart from changing an LED in my Metal Zone, that would definitely be me.

    Fast forward a bit and I’ve added the resistors and other small parts to the PCB first, and was going to solder in the pot but wasn’t quite sure how it would line up in the enclosure. From my photos below, would anyone be able to point out how i’ve managed to mess this up?

    Test fitting the pot and then the LED in the enclosure doesn’t seem to line up any way with the board. If the body of the potentiometer is directly over the board and connected to the top, the led would have to have really long legs to connect to D1 (pic 1). Or I would mount the pot legs the other way to the PCB and have the board sort of hanging over the space where the LED hole is, but that would get in the way of the foot switch (pic 2). Or do  you just get some extra wire to connect the legs of the pot to the board?

    I’m sure it’s a pretty boneheaded question, but any guidance would be much appreciated. Thanks!


    I like the second way myself. If you need to have it the first way, you can alweays run some wires from the LED to the board. The LEDS almost never line up perfectly (for me at least). I put the board and all the pots in and kind of jiggle the leads of the LED until it is in place before I solder it. In other words, the LED is damn near the last thing I solder.


    In the second picture, the pot is mounted with lug 3 in the lug 1 position.  This will cause the pot action to be reversed.  That’s fine if you don’t mind the reverse action.

    Big O

    I would just run the wires to the LED from the board as I have done this in many builds, using the photo #1 layout so the pot action is correct instead of reversed, as Wilkie pointed out.  If you have one of Barry’s 3PDT wiring boards, you can connect the LED to that.

    The way I contend with the LED is  that I form hooks or a J in each of the LED leads and the same with the the ends of the wires from the board.  Crimp the wires and LED leads together, solder them together using a heat sink clip on the LED leads and then cover the soldered joints with heat shrink tubing.  Just make sure the heat shrink tubing has been slid on the insulated wires beforehand so you can just slide them up over the solder joints before applying heat.  See below at top of image.



    Welcome Andrew. You’ve come to the right hobby. It can be as complicated as you want it to be but doesn’t have to be. Where help is always available because we have all learned from the same mistakes. And is always better than being at work. You are only limited here by your own imagination which we are going to help you expand. You’ll learn some electronics along the way. And if you can think it up then Billy, Wilkie1 and Cybercow can help figure out how to make it work. All that being said, I am never limited with my LED placement. Of course, you should always have forethought as to how things should turn out in the end, but I put the LED wherever I want it to be. Sometimes it’s position will fit perfectly with some art you picked out for the top, for example. Or maybe you feel like it should be to the left of the footswitch this time, or between the pots. Whatever you can dream up can probably be wired to work. So no fear. Just get some of Barry’s hook up wire and a decent soldering iron and warm that sucker up. Every time you’ll be smarter than the last and yes it will cost you a few mistakes along the way. I have a few builds with guitar picks covering wrongly placed holes. Looks great.


    Lately I’ve been using 3PDT boards that have LED pad built in (so I disregard any power LED on the board itself) and I have a little drill template that puts the LED hole where it needs to be next to the stomp switch.  Has made life a bit easier. 🙂

    Andrew Page

    Thank you all! Gonna give that a try today!

    Andrew Page

    Thanks again for everyone’s help on the OKF. Got everything wired into the enclosure, but now only getting a loud buzz when the effect is engaged (nothing when in bypass). When engaged and the knob is turned, the buzz will get louder/softer as you rotate and the LED will not light.


    I used the 3PDT board and wired the LED to that (tested it with a multimeter prior to soldering that in and functional), so I’m thinking perhaps I need to add a resistor (wasn’t included in the kit though). Using a yellow 5mm LED… it read something like .22 on the meter. But the buzz/hum, I’m not quite sure where to start.


    Would one of you kind folks out there be able to point out where I’ve gone sideways here?

    Andrew Page

    Was able to sort out that I had the 9v hot on the wrong post to the power input jack, and added a resistor to the “clr” part of the 3pdt wiring board. Now the LED will light up when the effect is engaged, and the clean signal comes through when in bypass mode.

    But when the effect is engaged all I get is a loud buzz/hum that will increase in volume until around 12 o’clock on the pot, then it changes frequency slightly around 4 or 5 o’clock. Have I completely fried the circuit with sloppy soldering?

    I’ve traced back the wiring to the input and output jacks, power supply, and to/from the main board and it looks to be as directed in the instructions. And I can’t seem to find anywhere that has excess solder creating a bridge where it shouldn’t be.

    I’m definitely enjoying the build, but man is this frustrating.


    Hi Andrew and welcome.

    Some suggestions follow:

    1) try the assemblage out of the box to see if the same symptoms obtain

    2) if not, then there may be a problem with some part of the PCB shorting to the enclosure. As a first step after these, try carefully reflowing the solder joints (preferably remove the transistors beforehand, as they don’t like excessive heat). Do this as systematically as possible and try again. AFAIK it’s quite unusual to fry an entire circuit.

    Then, if these steps produce no change, try replacing the transistors, which should be easy as you’ve socketed them. Double-check the pinout if they are different from the originals. There is quite a wide range that the board will accommodate. It may or not be that the 9V hot has somehow fried them. Speculating here, subject to correction from the moderators …

    Have a look at the audio probe option as well. Not quite sure where this is found within the forum categories, but this gives you a way of tracing the actual audio as it passes through the circuit. A very useful troubleshooting tool.

    Best of luck.




    Looks to me like your in T for tip pad is going to the ground lug on your in jack (black wire) and your red wire goes from the in ground pad to your BI pad but it’s very difficult to see I can’t really see the out pads but again you may have those wired incorrectly if your black wire is ground that also looks like it goes to the out T pad

    If you look closely at the pcb in and out pads one pad has a small T for tip the other is for ground

    Your in and out T for tip wires should go to BI and BO on the 3PDT pcb

    Andrew Page

    Billy, I owe you a beer. It’s alive!

    Thanks for everyone’s help!

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