flemming
Well-known member
I'm doing my best to avoid all the meme worthy troubleshooting behaviors with this one In my SeaMonk Build Report thread I noted an minor issue that I wasn't quite sure about. I decide to revisit it to see if I could resolve it or at least understand why it's happening. Here's the scenario:
Drive: All the way up *** See Update Below
Bottom: All the way down *** See Update Below
Comp: All the way up *** See Update Below
The humbuckers on my guitar are pretty hot. Using the bridge pickup if I hit the strings hard the pedal will start glitching, This happens less often with the neck humbucker or if I split the coils, but you can still trigger it if you try hard enough. Rolling back the volume on the guitar reliably resolves it. Here's a sound sample of hitting a chord with normal force and then pounding on it, and eventually rolling back one of the knobs to make it go away:
When this happens if I roll off the Drive or Comp knobs or turn up the Bottom knob a bit the problem resolves. I started digging into this with an audio probe and here's what I found.
<Deleted, See the updated picture below>
Pots in Green have an impact on whether or not it starts glitching. When actively glitching the spots in red appear to have the issue, while the spots in blue do not. A couple interesting things I discovered on accident. If I short pins 6/7 of IC2 the problem goes away, and if I short pins 7/8 of IC2 the problem appears. Pin 8 is not shown in the schematic but it reads 16v . So to me (a relative noob) this looks like everywhere voltage is introduced (either via pots or shorting) is a control point for the problem. Buuuut, then I guess I don't understand how that Bottom pot comes into play. So here I am, I'm not quite sure where to go at this point. I random guess at this point is either I have a problematic cap or I could stand to use a different size one somewhere to compensated for the signal level that my guitar produces. I thought I'd see if anyone had any thoughts before I contemplate replacing random components. I swapped out both TL072s just because that was easy and no change. The fact that it can be controlled via subtle knob changes in various places doesn't indicate a connection issue (to me), but you can see some pictures of the board in this thread if you're curious.
Drive: All the way up *** See Update Below
Bottom: All the way down *** See Update Below
Comp: All the way up *** See Update Below
The humbuckers on my guitar are pretty hot. Using the bridge pickup if I hit the strings hard the pedal will start glitching, This happens less often with the neck humbucker or if I split the coils, but you can still trigger it if you try hard enough. Rolling back the volume on the guitar reliably resolves it. Here's a sound sample of hitting a chord with normal force and then pounding on it, and eventually rolling back one of the knobs to make it go away:
When this happens if I roll off the Drive or Comp knobs or turn up the Bottom knob a bit the problem resolves. I started digging into this with an audio probe and here's what I found.
<Deleted, See the updated picture below>
Pots in Green have an impact on whether or not it starts glitching. When actively glitching the spots in red appear to have the issue, while the spots in blue do not. A couple interesting things I discovered on accident. If I short pins 6/7 of IC2 the problem goes away, and if I short pins 7/8 of IC2 the problem appears. Pin 8 is not shown in the schematic but it reads 16v . So to me (a relative noob) this looks like everywhere voltage is introduced (either via pots or shorting) is a control point for the problem. Buuuut, then I guess I don't understand how that Bottom pot comes into play. So here I am, I'm not quite sure where to go at this point. I random guess at this point is either I have a problematic cap or I could stand to use a different size one somewhere to compensated for the signal level that my guitar produces. I thought I'd see if anyone had any thoughts before I contemplate replacing random components. I swapped out both TL072s just because that was easy and no change. The fact that it can be controlled via subtle knob changes in various places doesn't indicate a connection issue (to me), but you can see some pictures of the board in this thread if you're curious.
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