mantle fuzz , effect on , very low output

mnll

New member
I built the mantle fuzz (blue box) and i can barely hear the effect and my volume pot doesnt seem to do anything. I had tested it with a headphone amp and i had to run a maxed out volume muff into the blue box as a volume boost and turn both the gain and volume on my headphone amp to the max...just to barely hear it. The volume pot doesnt seem to work and if i remember right from last night, when i had the volume pot at 0 i still had sound. It sounds like the effect is working but i barely hear it. I couldnt tell if the blend knob was doing anything since the output volume was so low and it was a headphone amp like i said. All my other pedals and fuzzes work fine through my headphone amp before u say anything so its not like thats the issue. I checked all my resistor and capacitor values and those appear to be fine, but i will double check all those again tonight or sometime this weekend.

Anyone know what might cause these issues...the pots not working (at least not the volume) and barely an output but the effect is working?
(In the pic i didnt clip the led leads until i made sure it was the correct way around so those r sticking out but not touching anything in the pic)
 

Nostradoomus

Well-known member
Is that blue electrolytic 100uf?
Does the tip of your input jack touch the back of the pot when a cable is plugged in?
Can’t really see it well but it looks like you may have your input hooked up to the ring of the jack and not the tip
 

mnll

New member
Is that blue electrolytic 100uf?
Pretty sure but i will check when i get home. I always double check components when putting them in and then once i was done i checked it again when it wasnt working and appeared fine.

Does the tip of your input jack touch the back of the pot when a cable is plugged in?
I will have to check this, but the tip is opposite of the pots...if anything is possibly touching the pot itd be the ring. The tip in the picture is the one thats closest to the camera and parallel to the backplate when thats put on. I will check if maybe that tip is touching the backplate when its on. The wire is connected to the tip correctly, but maybe its hard to see. The ring has nothing connected to it.


Could it be the pots are backwards? the drill template was a little different with the led in the wrong place...so im wondering if it could be that i didnt put the pots on correctly. With the drill template wrong, and the wiring diagram showing a different pcb, and being my first pedalpcb pcb, my first inclination is this is a misinterpretation of the documentation. I will post back tonight when i check all these things.
 

mnll

New member
So checked all my resistor and capacitor values a few times again tonight and those all check out fine. I rotated the input and output jacks to ensure they aren't touching anything. All my solders seem fine and ran some extra solder some of them to be sure. This is probably my 10th build and I haven't had solder issues since my very first pedal. Right now I'm ruling out all these things.

I can hear the effect as if the level is at 1 out of 10. The volume pot is doing nothing, so I can turn it to 0 or 10 and the volume is the same. The blend pot might be the same issue but it's hard to tell with such a low volume. It doesn't help that nobody on the forums has posted anything about building this pedal. All these parts are new, some I've had for awhile but haven't used. I gotta believe something is wrong with this pcb because I'm out of options. If anybody out there has built this thing I'd love to hear from you
 

mnll

New member
That blue electrolytic cap in the image was 10uf, to answer your question from earlier. which is what is printed on the pcb. There is a dark blue/purple electrolytic cap on the right side of the ICs and that is a 100uf. All these components are the correct ones according to the pcb and part list.
 

Servant07

Member
Ahh you are at the worst stage of trouble shooting. When you hope you just did something stupid and eventually catch it, but it's not that. If you have never built and used an audio probe, now is the time. It's a great tool to learn how to use and this is the perfect example of when to do it. When I audio probe I hook an mp3 player up to the pedal to have continuous audio going and then trace your way through the circuit from the beginning and you will find the spot where the audio signal dies.
 

mnll

New member
I used the audio probe method and turns out a new switch I bought from smallbear was faulty. The clean signal was coming out of the switch fine, but the wet signal part of the switch was busted. The signal coming out of the volume pot was just fine all the way to the switch, so it was something inside the switch that was busted. I get a lot of parts from smallbear, so I'm not knocking them at all, but wanted to clarify what the issue ended up being. It was one of the low-profile switches that I like to use. I have a couple spare switches so I swapped another new one in and everything works great now. I'm going to get a refund for the broke one.

I found a website or blog where someone is demostrating how to fix a broke pot and he is describing the same low volume kind of issue I was having. The probe helped me identify this issue.

Thanks everyone for helping me.
 

mnll

New member
Cool. its a very easy build. I checked out a couple part lists from different sites and they were all about the same. One document had .05uf caps where the pedalpcb version had .047 caps near the output. Smallbears part list had a silver mica cap for the 300pf so i used that instead of a ceramic. I got the large mxr knobs and they fit the pedalpcb template great so you could use the dunlop knob covers with those if u wanted to. I didnt try this yet but pretty sure the knob covers would fit. The knob covers r only 2 bucks from smallbear.

Lastly, be aware everything was good on the drill template except the LED position. You have to drill the LED hole a little higher than whats on the template.
 

Nostradoomus

Well-known member
Good to know. I just built it! Ran it through my test box, all good...not sure it deserves to be out in a box yet hahaha
 
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