Harbinger droning

[Ash]

Hi guys,  I have been working on my Harbinger and have a horrible droning sound. In bypass there is no noise but when I switch it on the sound starts. The noise goes with rate of the light. Everything works and I can hear cool sounds its just has this extra noise with it. The noise persists regardless of settings.  I built it for 18v bc I had a wall wort, so why not? I have built 20+ pedals but apparently been pretty fortunate. When I go over the circuit with my audio probe it starts sounding funky at c6. I reflowed a bunch of stuff just to be sure but no luck. How do I know if the cap is bad? Any suggestions would be great.

[midwayfair]

Audio probe the dry and effect paths and see where the noise is introduced. Does it change AT ALL when you switch between chorus and vibrato mode?

[Ash]

The effect changes but the droning is still there when I switch between chorus and Vibrato. The modern/vintage switch just boosts the droning. I am still a novice at reading the shematic so the dry path/ effect path honestly doesnt mean anything to me. I assume you are talking about Brians color coding on his curcuit diagram (thick and thin red/blue lines). I would be happy to read up on it if you can point me in the appropriate direction. Does a particular color indicate the dry/effect path? I could assume but that doesnt really get me anywhere but trouble, lol. Thanks in advance Jon. Btw I have built several of your circuits and enjoy them. 

[midwayfair]

This is a very complicated project for a beginner.

The schematic is broken into 3 parts. You'll notice that they aren't directly connected to each other. The top right is the power supply. The part connected to the bulb is the LFO. Everything else is the dry path. Start at the input and work your way toward the output, taking notes as you go.

Also, post voltages, and please follow the rest of the rules in the Tech Help Rules thread.

[Ash]

Thanks Jon. I will double and triple check everything. Like I said I am not new to building pedals I just suck at schematics and most problems i have been able to find without much trouble.  My best guess is a bad ground somewhere I just have to find it. My DMM is acting a bit squirrelly too so thats not helping. Thanks for the advice. Is there a good place you recommend to learn how to read schematics?  I certainly don't want to waste anyones time, unfortunately I have never come across anything that really broke it down.

[Ash]

I did notice one thing going through the populated board. For ic2 I have L7815 not LM7815. They are both +15 voltage regulators but the l7815 is 1.5amp output vs the 1amp of the LM7815. Is it possible this could be the issue or is that unlikely?