[brach]

Great! I’m glad it worked out for you. Most likely touching up the solder joints fixed it. The solder underneath the resistor wouldn’t haven’t made a difference unless it was shorting 2 solder joints.
Anyway, good job! Enjoy the pedal!

[brach]

Yes, sorry, I meant the phase switch.

[brach]

I’m glad you got that figured out. As you discovered, the instructions are very important to follow.
Please read about calibration mode. That should help you troubleshoot the low side. I’m assuming you have the mode switch set properly for harmonic tremolo, correct?

[brach]

What step do you get stuck on in the troubleshooting guide?

[brach]

Somehow the relay isn’t switching. Make sure all the components in the relay circuit are installed properly. Use a magnifying glass to check for shorts around those transistors and diodes. It sounds like it wants to switch, but one of the coils is being held high and not allowed to go low. Other than these suggestions, I don’t know what is causing it. You may have to pull the transistors off the board and manually toggle the relay (with jumper wires from the 5v rail) to ensure it works properly.
Good luck!
-Brach

[brach]

I assume you’ve tried a different mic cable, correct?
I suggest re-flowing all the joints on the board and xlr cable, even the ground lug on the tin. If it used to work but doesn’t now, most likely a solder joint is cracked on a tiny level that is hard to detect without a microscope.
Alternatively, maybe the sensor disc got cracked or damaged somehow. If you unsolder the sensor cable, do you still get the ground buzz? You’ll most likely get a different type of buzz caused from the input of the circuit being open, but it should sound different. You can test this further by installing a couple of very low value capacitors (anywhere around 100pF or so) between PZ1 and ground, and PZ2 and ground, which emulates the piezo sensor. If you do this, the buzz should go away completely, if the problem is the sensor.

-Brach

[brach]

I have no idea what you mean about getting “a 4”. What units are you referring to…volts, decibels, milliamps?
To get more depth you can adjust the tone trim pots (high and low) to allow more signal to get through the optocouplers. You can try turning them both up the same number of turns until one of them maxes out….just so they keep the same ratio of high and lows.
Good luck!
-Brach

[brach]

You seem to have a bad ground connection somewhere. You can check this by doing a continuity test between pin 1 of the xlr connector (the ground pin) and the copper tape around your piezo disc. You’ll probably have to puncture a small hole in the plasti-dip, but you can always paint another layer of it on later. Also make sure that you are getting continuity to the metal enclosure from pin 1.
Good luck!
-Brach

[brach]

It sounds like there is something weird going on with your effects loop if the same thing happens to other pedals.
-Brach

[brach]

Alex,
(sorry for the later reply)
I’m glad that helped with the power supply.
It sounds like something is wrong with you effects loop (or Quaverato). There should not be a volume drop at all. The input impedance of the Quaverato is 1M ohm and that is overly sufficient for any line level output. Have you used this line out before with other pedals? Does the Quaverato work fine when a guitar is plugged into its input while its output is plugged into the guitar amp input jack? Are the cables known to be all good? I don’t know what else it could be. I’m sorry, I hope you are able to figure this out.
-Brach

[brach]

Have you tried using an isolated power supply for the Quaverato? Typically, the Quaverato performs best when it uses its own dedicated wall wart, preferably a linear power supply with a transformer instead of a SMPS.
Let me know if that changes things at all.
-Brach

[brach]

Wow! That’s really nice of the retailer!

[brach]

This is a very strange issue. It’s strange that it is only happening on the high side, but it could be that both sides are affected the same, but the LPF is filtering out the noise on the low side. The fact that the noise seems to change characteristics with the rate knob makes me think that it has something to do with the microcontroller, although I can’t imagine how it would be behaving this way. If you have a USBTiny programmer, you may consider re-flashing the microcontroller to see if that changes anything. If you happen to own an oscilloscope you can scope the PWMs coming from the microcontroller on each side (high and low) and compare the wave forms.
One more thing I wanted to ask is if it behaves any differently when the mode switch is flipped.

-Brach

[brach]

Since you said the sound was coming through only on the high side of circuit (with calibration mode), it must be responsive to the high trim pot. Are you able to manipulate (lower) the volume level of the noise with that trim pot?

[brach]

I’m sorry for the delay in responding. I just got back in town.
This is a very strange issue. It almost sounds like the PWM from the microcontroller is making its way through the optocoupler to the signal path. My initial thoughts are to ensure that all the components are installed correctly (proper orientation) and to ensure all the solder joints around Q1, opto1, and the trim pot are solid and not shorted to anything. Also ensure that the solder joints don’t have too much solder on them; sometimes this can cause the joints to act as antennas, broadcasting the signal to other parts of the circuit. Also make sure all the components are installed correctly.
Are you testing this with the sine wave function? You should be for these tests.
You mentioned that you adjusted the high trim pot. Please move it in the opposite direction that caused the purring sound. It could be set too high. Ensure that it is working properly; you should be able to turn the high signal off by adjusting it all the way in one direction (25 turns). Does purring sound go away when you adjust it to where all the high signal is gone, or does the purring stay the same or get louder?

-Brach

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