Leprechaun (Rainbow Machine) Build - Weird Issues

[andrew]

Hello, venerable forum! New builder, here — this is only my second non-kit build — and it looks like I've found myself a bit over my head.

I have built a Leprechaun (Rainbow machine) clone and it works... ... ... kind of.

With certain settings I can get a gentle vibrato sound, and with certain others I get a sort of lofi delay sound. They're honestly both pretty pleasant but, of course, not what I'm looking for out of a Rainbow Machine clone. Between these two tones there's minimal pot interactivity, they don't do much. When the Regeneration/Magic footswitch is activated, the cascading effect sort of triggers randomly on its own — in some settings it's triggered by an input tone, but mostly its random.

Scoured the forums and didn't see anything like this posted about yet, happy for a redirect if I'm mistaken.

I've scoured the PCB and, to my beginner's eye, everything looks sound. Don't see any solder bridges, gave both sides a decent scrub with some alcohol. Hoping for a magic cure (obviously), but would be very grateful for some good tips on where/how to test different components (I have access to a full-featured digital multimeter).

A few pictures attached.

 

[Purplehaze13]

Hello, don't worry I am a profesionnal troubleshooter. (I am laughing my own Leprechaun doesn't work too!) But I can see that you forgot the wire between Tip and Switched Tip pad.

 

[andrew]

Oooo, very interesting. I completely missed that part in the build doc. I do plan on adding an expression jack, just don't have it yet.

Do you think that's part of the issue? Or just something you noticed and wanted to point out?

Also when the expression jack does come, do you know what part of it I'd be connecting to that Switched Tip pad? I'm starting to suspect I've bought the wrong kind of jack (again).

 

[peccary]

I'm pretty sure it's likely the jumper. I built one of these and forgot the jumper as well. It still sounded cool but was kind of uncontrollable and I wasn't getting a lot of play between the controls. The jumper fixed it and made it even wackier. Give it a go as you can remove the jumper pretty easily when you add the jack.

 

[andrew]

I'm pretty sure it's likely the jumper.

But I can see that you forgot the wire between Tip and Switched Tip pad.

Well, thanks to you both! I'll confess I was a little skeptical about such a tiny thing making such a big difference, but it does.

 

[peccary]

Well, thanks to you both! I'll confess I was a little skeptical about such a tiny thing making such a big difference, but it does.

Glad it worked out for ya!

I gave the one I built away to a friend, but I kinda wish I'd built a second one for myself. I may one of these days.