EQD Hummingbird/Vox Repeat Percussion Ticking

Started by Zounds!, July 18, 2015, 02:42:58 PM

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Zounds!

I know this is a common issue, as I've read a whole bunch of threads looking for the answers to this but figured I'd see if anyone had any ideas I haven't tried yet. I built an EQD Hummingbird with this layout:



I tried MPSA18 for Q2 but no luck. Realize the issue is probably, as RG and others have explained a bunch, the 100uf cap on the bottom of the board is discharging to ground which it shares with the audio path. So I get a ticking sound when I'm not playing that sounds like a metronome. It is audible even with the depth pot turned all the way counterclockwise (this may be a different issue though, because my signal is also effected, where it is supposed to be try at that setting). To try to correct this I cut the trace on the ground strip to the left of the negative of the 100uf and removed the sw2 wire. I then wired the grounds like this:

100uf cap/39r resistor--> output jack sleeve
sw2-->input jack sleeve
ground strip--> 9v ground lug
input jack sleeve --> 9v ground lug

That didn't change anything at all....anybody spot another point on this layout where that tick might be leaking into the audio path? This circuit is a modified Vox Repeat Percussion, so here's the schematic for that, which I've tried going through but am sort of unsure about where leakage might occur: http://bmamps.com/Schematics/effects/Vox_RepeatPercussion.gif (huge image)

Thanks for any advice!

Zounds!

D'oh. I had Q2 and Q3 swapped. Put them in the right spots, swapped in the MPSA18 and patched my cut in the ground strip. Now all of my grounding is just as in the layout but sw2 is grounded directly to the 9v jack. No tick! At all! I'm amazed! My only issues now are that

a) I'm getting a volume boost above unity gain at all points on the Level pot - I subbed in an A50k until I can go parts shopping, but I don't imagine the taper would be causing this?

and

b) The depth pot never actually cuts out the effect. This circuit is supposed to double as a clean boost with the depth turned totally counterclockwise...mine still has a bit of effect. Not that I want to use it as a clean boost at all, but something is awry...

Zounds!

I never grounded the Level pot, so volume issue solved. Another stupid mistake. Hopefully some of this will be useful to someone down the road!