Emerson EM-Drive first build no signal

Forum dedicated to helping people debug and troubleshoot non-functional pedals or builds. Please use an clear and informative title, indicating circuit and basic problem. Don't forget to mark the issue as fixed if this is the case.
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lthobbes
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Joined: 30 Nov 2016, 20:34

Post by lthobbes »

Hello guys!

I had wanted to get into the hobby of figuring out how pedals work since I use them all the time. I decided to start with what seemed like a relatively easy build, and after doing research I found the schematics for Rugeb's modified Em Drive with a tone knob. I tried to put the schematic on veroboard but as it was my first time I am almost sure this is where I went wrong. I hooked the pedal all up as best as I could and when I plugged it in to my board all seemed well. In bypass my signal is fine, and I can play with the other pedals. My problem is when I turn the pedal on... The guitar signal cuts out and my amp buzzes/hums (the volume depends on my volume and gain knob so I think those are plugged in correctly...)

Can anyone help me double check my work? I don't know enough to figure out whats wrong and I have tried multiple things. I looked online and people said that amp buzz is probably a grounding issue.
Other info: I bought my parts from Mouser Electronics. I tried two transistors: 2n5088 and MPSA18. I accidentally cut the legs too short on the C1 capacitor... I just soldered them back on which is why the cap is sideways. I have no idea if this compromises the value but that also might be causing problems? Idk.

Here is the link to the pictures: https://s350.photobucket.com/user/jwalt ... lus%20Tone
Let me know if there is trouble with the link :D

Thanks so much for your help!

- lthobbes (a confused noob)

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sliberty
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Post by sliberty »

My approach to debugging a pedal that doesn't produce any sound is to use an audio probe to determine where the signal stops flowing. I would start by probing at the input to the board. Then I would probe in front of the transistor. Then I would probe after the transistor, and finally at the output jack. Once you find a spot where there is no signal, you will know that the problem is before that spot in the circuit.

If you don't have, or know what I mean by an audio probe, it is essentially a capacitor connected a chop stick, connected to a working amplifier (I use one of those little portable amps that people use for an MP3 player). Here is a link:

http://www.tdpri.com/threads/how-to-mak ... be.339721/

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lthobbes
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Joined: 30 Nov 2016, 20:34

Post by lthobbes »

Alright thanks! I'll have to test it out as I am going off of the assumption that my veroboard layout is what is not working

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