Fuzz Factory musikding kit acting weird

[deadfest]

This is my first pedal build, I bought it from the Musikding page.
Every cable seems to be woking right, when it's turned off the clean guitar sounds good but when I turn it on the LED works and I get that weird sound that the fuzz factory makes.
The volume pot doesn't seem to work and the guitar doesn't make any sound, the only thing that works is that crazy effect and every knob makes it sound different.
Any ideas why the guitar doesn't sound? Thanks.

[deadfest]

I think the Stab 5k potentiometer just burned.

[eh la bas ma]

Hello, welcome.

I don't think a pot can burn. Please, can you post schematics and some clear pictures of both sides of your build ?

If you have a multimeter, you can check for ground  continuity between the board, the 3PDT, and both jacks. Are you sure there is no confusion with IN and Out jacks ?


Edit : I was mistaking, pots can burn, sorry. I just never heard about it before.

[deadfest]

I don't have a multimeter. But the pot literally catched on fire and started smoking. Sorry if it looks messy, it's my first build haha. And no, the signal goes well when pedal is not turned on, but I don't get any sound when I turn it on now.

[idy]

Welcome!

The "stability" pot allows you to dial the voltage down, they used to call this "dying battery" sound. All the power for the circuit goes through it. If there is a short around one of the transistors it would let enough current through to heat up and smoke or spark, and will be ruined. You need to find out where the short is before you replace the pot.

You really need a multi-meter, and they can be had cheaply.

[idy]

For example, if one of the terminals on the stab pot was bent and touched the enclosure, that would do it.

[deadfest]

How do I know which transistor is the bad one? And I have a 500k potentiometer laying around, that would work?

[antonis]

A 5k pot across 9V supply needs to be rated lower than 16mW to be burned out..

[deadfest]

So that means...?

[antonis]

That part of your pot (less than 10%) is burned..
(the part between wiper & lug 3..)

[eh la bas ma]

a picture of the soldering side might help us to find suspicious solder joints.

A multimeter is needed to build stompboxes, to find shorts, read voltages, etc. VC97A is good, you can read Hz, which is useful with modulations builds.

[ElectricDruid]

+1 what IDY said. A pot absolutely can burn! I've smoked a few over the years. If the pot is wired as a potential divider, it's clearly much harder to do, since even with a 1K pot, you'd need a good amount of voltage (and how much would depend on the pot type you're using). But if the pot is wired as a variable resistance (like the Stab pot here), its resistance goes to zero or very close to it, and in that situation almost any amount of DC across the pot is enough to burn holes in the track. This is why series resistors along with variable resistors are often a good idea, especially when testing.

If it burns, you get a puff of smoke and a funny smell, and (if you're lucky) a dead spot in the track where the pot no longer makes a connection between the wiper and the outer lugs. This is what Antonis meant about "that part of your pot is burned", and it might well be 10% or less. If you're less lucky, the whole thing is junk.

[deadfest]

it literally catched on fire, I'll post photos of the soldering if I can

[deadfest]

[idy]

That picture of the flaming pot is a winner.

That solder side is crazy. You need to clip the ends of the component leads so they don't stick out (far) past the solder. The best tool is a "flush cutter." Another cheap but necessary thing.

There are videos with soldering tips. Eh la bas ma has posted the quickest guide to soldering, the good, the bad and the ugly. Study it and do what it takes to make your soldering look like that. And cut all those stray wires.

[puretube]

smokin` what?
https://www.diystompboxes.com/smfforum/index.php?topic=691.msg4539#msg4539

[deadfest]

Update, I soldered some things better and the pedal now passes a very low signal (clean one) when it's turned on.
Does this have to do with the burnt pot?
Thanks for all the help!

[idy]

Voltages. Three transistors, 3 pins each, that's 9 measurements. Still no meter?
Are you telling us you did not replace the obviously scorched and damaged pot?

[deadfest]

I don't have a 5k potentiometer laying around, I have a 1k one.
I've been busy these days but I'm planning to go to an electronics shop to get a new potentiometer and a multimeter.

[idy]

You could remove the stab pot and just short the two wires that go to it. It is just reducing power to the circuit to make it unstable.

But better to get a meter first and confirm that the short that fired the pot is gone. You would (power off) measure resistance between the power rails (9v and ground.) You should not see a short. Then you can try power without killing the battery.