Build Your Own Clone Message Board

A few years ago (2019) I ordered a Green Pony kit and assembled it. The build went smoothly but when I powered up the pedal it didn't seem to operate as it should. I looked into it briefly at that time but then it got put in a box when life happened.

So today I pulled it off the shelf and started to investigate. Here are the symptoms:

Pedal passes signal, but essentially the drive control seems to operate backwards as far as what I am hearing. With the control turned fully CCW the pedal has definate gain compared to bypassed. Rotating the Drive Control fully CW the output is reduced. Engaging the clipping feedback diodes doesn't cause any audible clipping at any control setting.

I then injected 1khz @ 1v RMS into the input. With the Drive Control turned full CCW I get 4.5v at the output jack, turned full CW and now the output us 600mv. Basically confirming what I am hearing with the guitar and amp.

Interestingly pin one IC1 shows clipping on the scope when the drive control is cranked and cleans up when it is turned down.

All internal voltages are seemingly correct. The charge pump is working and all the op amps are passing signal. Somehow it seems like the drive control is just reversed//

Has anyone else encountered this odd behavious?

Thanks,

Phil

Sounds to me like the Drive pot is working fine but the drive circuit itself isn't functioning. In addition to controlling the amount of gain from the drive circuit, the Drive control also blends in more or less of the clean signal. So if the drive stage isn't working, the pedal will behave as you describe.

It would be helpful to see a couple of photos of your build. They need to be large, well lit and well focused shots of both sides of the PCB.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

If you want to inspect the drive stage of the circuit, I've circled it on the schematic mark up below, and you can cross reference the component locations on the PCB map that follows:

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

From what I see with the scope the entire drive circuit is working fine. The feedback clipping and the tone switch work as well. I have the board out of the case now and have been going through the circuit point by point looking at the signal. Somehow the signal is just getting lost somewhere. The bypass part of the drive circuit is obviously working normally.

I was really struggling with component identification on the board since the component ID isn't screened on the board. Luckily I found the marked up photos in another thread and I printed one out for the GP.

I posted here just to see if anyone else had seen a similar behaviour, the "been there done that got the T-shirt" deal. I built my first home computer in 1981 (Heathkit H89) and have worked on electronics ever since so my experience level reduces the likelihood of many of the usual assembly & soldering errors. I believe I tested every component before soldering it in place too but it was a few years ago. But I am human.

It is a simple circuit, I'll sort through it and report back when I find the issue.

Thanks for the follow up!

Phil, KBØNES

Mystery solved, R10 the 1K resistor was open so the signal from the drive circuit didn't feed to the next stage.

I'm pretty sure I confirmed all the resistors with a DMM during assembly. Either the lead bending or heat from soldering got it!

All good now.

Cheers!

Phil

Glad to hear you were able to chase down the problem to that bad resistor. Enjoy the new pedal!

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2