Leprechaun Exp. Input produces harsh noise

[Pilzfuss]

Hey to all Pedal Pcbers !

I have built the Leprechaun and i really really like its overall sound and im so glad that it really works and does its job

BUT ! The expression Input is really really strange, i wired it according to a post here in the forum, where RTS numbering was described like it should be. If there is nothing connected to it, nothing strange happens, but if i connect a Expression Pedal to the input, it produces a harsh noise that transforms the whole sound of the pedal completely and it also shows no reaction when i press on the expression-pedal.

The attachment shows my wiring.

Do you have any idea what could be the faulty circumstance here ?

 

[Cybercow]

The TRS expression jack needs to be a switching TRS pass-thru type - like this . . . . .



From what I can make of your TRS jack, it is NOT the switching type.

Hope this helps.

 

[Pilzfuss]

Well thanks alot for that quick reply!

Could you figure out what exact kind of jack that is ?
Cause the strange thing is, the one i used, was put into the box by the shop where i bought the pedal... sooo somehow thats a little odd ?

Ill try it with another expression pedal to rule out all possibilities. Lets see

Best wishes !

 

[Cybercow]

Well thanks alot for that quick reply!

Could you figure out what exact kind of jack that is ?
Cause the strange thing is, the one i used, was put into the box by the shop where i bought the pedal... sooo somehow thats a little odd ?

Ill try it with another expression pedal to rule out all possibilities. Lets see

Best wishes !

I'm not able to sort out what precise type of jack you have there from just that one photo. I would need to see other angles of it and a better view of how it's wired. Did you not install that expression jack?

 

[Pilzfuss]

Yeah i installed it, as it was part of the diy-kit :3

As far as i can see, what id need is the jack in the attachment ?

Or do they also differ as how they are built even if they have the 6-way-style-solder-points ?

 

[Cybercow]

Yeah i installed it, as it was part of the diy-kit :3

As far as i can see, what id need is the jack in the attachment ?

Or do they also differ as how they are built even if they have the 6-way-style-solder-points ?

Yes. That one looks like the one you need. Just note which lugs will ALWAYS be wired to the PCB when a TRS plug is inserted.

 

[Pilzfuss]

Yes. That one looks like the one you need. Just note which lugs will ALWAYS be wired to the PCB when a TRS plug is inserted.

Ok thats > 1 < very good to know !
That that might fit !
But another question stumpled into my mind, could it produce the noise because i used a mono jack cable ? Would that make sense ?

Or might the jack just be the wrong one to use, even if it was part of the building kit... ?

Oh well xD

 

[giovanni]

The jack and cable should be stereo yes. You can use a multimeter to confirm that the connections to the jack are as intended (follow the build doc), ie, ring, tip and sleeve are connected to the correct pads and not to each other. Not sure how the shorted tip is supposed to be connected when no jack is plugged in, maybe @PedalPCB can shed some light.

 

[Cybercow]

The jack and cable should be stereo yes. You can use a multimeter to confirm that the connections to the jack are as intended (follow the build doc), ie, ring, tip and sleeve are connected to the correct pads and not to each other. Not sure how the shorted tip is supposed to be connected when no jack is plugged in, maybe @PedalPCB can shed some light.

The photo supplied above shows a working expression jack connection. In this image, I marked up the wiring so the connections are clearer.

 

[Pilzfuss]

I got the jack, wired it up...
The harsh-digitally-distorted-noise still is coming out. As soon as i wether plug a stereo or mono cable in, it doesnt care...

I used a BOSS-FS-5U
and a VFP 1/25
exact same outcome.

Could anybody figure what can possibly be the issue here the ... so strange

 

[Robert]

I used a BOSS-FS-5U
and a VFP 1/25
exact same outcome.

This is the problem.

That jack is for an expression pedal, not a remote footswitch.

I'd be willing to bet those footswitches are grounding the 3.3V supply (which is bad).

 

[Pilzfuss]

Well then ill need one to test !

Has anybody tried what happens when he connects a unconnected mono / stereo jack to his normally working unit ?

That would be very interesting.

 

[Robert]

You wouldn't want to plug in a mono cable, that would have the same effect as plugging in your footswitch.

A stereo cable with nothing on the other end would be similar to turning the Pitch control all the way down.

 

[Bricksnbeatles]

Well then ill need one to test !

Has anybody tried what happens when he connects a unconnected mono / stereo jack to his normally working unit ?

That would be very interesting.

If you don’t have an expression pedal on hand but want to double check that the jack is working in the meantime, you can wire up either a 10k, 50k, or 100k pot (not sure which one is the standard for the rainbow machine, all three are common values depending on the pedal manufacturer) to to a TRS jack with the tip connected to the wiper of the pot (with a 1Kohm resistor inline to act as a current limiting resistor—in many applications it’s not needed, but some pedals such as strymon recommend it, and it won’t really effect anything either way) with the outer lugs each connected to the sleeve or the ring (depending on which way you want to be minimum and which you want to be maximum— or you can wire up a dpdt to let you switch on the fly)

 

[Pilzfuss]

Whoah okay thanks a huge lot for that tip ! Lets see what is quicker id have to kill a good cable for that... Ill just get a cheap expression pedal in the meantime. Or atleast order one !

Very helpful altogether !