If I turn the pot too tightly, there's no sound. Is it a short to ground?

[Ruki]

I made a Blue Note OD pedal from the effectslayouts website.
It all worked fine. But when I put the volume and gain pots in, I get a problem.

When I tighten the pots with a wrench, they probably short out to the ground inside the case, and there's no sound.
It's not that I'm tightening them too much more than necessary. As a test, I made all the pots floating in the air, not touching anything. I put a ground wire on the surface of all the pots, and there was no short. They sound fine. All I can understand is that something is wrong. Can anyone identify the cause of this?

Please forgive my very novice question. Thank you.

[GibsonGM]

Can you examine very closely where the pots lay inside the enclosure, and be sure the lugs are not shorting across themselves??  As in, one or more lugs touching the enclosure, which is grounded (and metal), so any contact at all there will short out the pot.     

Using a DMM (digital multi meter) set to 'continuity' to touch each pot lug, with the other probe on the enclosure, can rule this problem out.  If it works out of the box, and does not work in it, then it is likely either this problem, or something else that is touching something it shouldn't.

Final thought - check that the enclosure is in fact grounded to the correct 'ground thing'.  Most pedal grounds are negative, the "-" of the battery.   It's good practice to learn how a pedal is grounded, and to be sure each point in a build (say, the input jack) that needs to be connected to ground, is.

Hope it works!

Welcome to the forum!   In the future, it's useful if you can post a link to the actual pedal you built - the schematic if at all possible and not the layout  

[Ruki]

Thanks for your advice. It's very helpful.

I did a DIY using this layout.

http://effectslayouts.blogspot.com/2016/02/rockett-blue-note-od.html?m=1

Looking at the layout, it looks like there are pots that are not connected to ground. Do you think that's the cause?
But when I tighten either the Gain or Volume pots, there is no sound.

All the lugs coming from the pots are not touching anything inside the case. And yes. There is a negative current inside the case.

[Baran Ismen]

Just for testing a possible ground short from the pot body, put some insulation tape inside the enclosure, covering the pot holes. Make sure it covers at least 2x area of the holes. Then with a hobby knife, cut out the holes again, so that you'll have enough insulation taped area that will touch the pot's body when squeezed tight and -hopefully- prevent any shorts.

Give it a go.

[ElectricDruid]

Welcome Ruki,

Could we see some photos of what you've built so we can see what you've done, please?

We might be able to spot something you've missed.

Thanks!

[duck_arse]

also welcome. in the photos you are going to show for the ever-asking Tom, will we see wires soldered into the rivet holes of the pot lugs?

[Ruki]

I don't have much time today, but I'll try the insulation tape idea! It could definitely be a good idea if I can't pinpoint the cause.

I'll also try to post some pictures, which might pinpoint the cause.

I'd really appreciate everyone's help. Thank you.

[FiveseveN]

It looks like the pot pins are bent in a U shape, in a way that can contact the enclosure when installed.
In other news, are those shielded cables? The shield doesn't do anything if it's open at both ends. LE: never mind, I see where they're connected to the PCB now.

[GibsonGM]

That is a rather clean build    I would try making 'washers' out of cardboard to fit between each pot and the enclosure, and add this to the tape layer you stick on it.  Just an abundance of caution, I have also had to do this.  I would not bend the pot pins back next time...

Since the pots are wired and not on a PCB you could try assembling the thing, put no nuts on the pots, and push them away from the enclosure a small amount 1 at a time (or all together if this fails to make the problem occur). It might reveal the location of the issue.   Also - pots can rotate when tightening the nut, and contact things they should not. I sometimes have to get a finger or object in behind them to prevent this.

It does seem that insulation between pots and enclosure has a good chance of fixing this, though.   

[ElectricDruid]

Since I can't see any connection to the enclosure anywhere else, I don't see why the pot bodies touching the enclosure would cause a problem. Even if the enclosure were grounded, which it doesn't look to be (plastic jacks, insulated power jack) then the pot bodies being grounded shouldn't cause an issue. So I'm not convinced we're looking in the right place to find the problem. Yes, the pot lugs are bent over a bit, but they're still miles away from touching the pot body, and tightening the pot into the enclosure wouldn't affect that anyway.

I think something else is shorting to the enclosure somewhere else.

[antonis]

Are those electros in an inferior position so they need hi-heels..??

[duck_arse]

we need a circuit diagram. and a panel layout. is it only when BOTH pots are tightend, or one or the other tightened? is the lid on/off involved? are both pots on the same side of the case? if you put your pot into the front panel and then rotate it, does the CCW lug come in contact w/ the case? there's something to try, dry fit some pots and switch in the front panel, and rotate them, see if they can contact each other.

[Ruki]

Thank you everyone.
I thought the gain and volume pots were shorted somewhere, but I could never figure out why.
I tried using the nut to make the pots themselves taller, but they still shorted. So I ended up wrapping the pots in more electrical tape. That fixed the shorting problem, and everything is fine now. But it's a black box because I never know where the problem is. I never knew which part was shorting. But thanks to everyone's kind advice, I was able to solve it!