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Richie,
It seems that you may have a couple of issues going on at once. Most likely, the biggest issue is probably a short or open somewhere. Shorts can sometimes happen when you close the chassis because all the pots and pcb and everything can get kind of squished together causing something to be connected that shouldn’t be connected. Check to make sure the backs of the pots aren’t shorting against anything, possibly through the insulation paper (make sure there are no punctures in it). Also, this type of issue can be caused by bad solder joints that aren’t making good connection. Please check and re-flow the solder joints on the board (pay close attention to the solder joints on the pots).
When you get the solder joints and connections situated, that may solve all of your problems. But i am curious how calibration mode worked for you. Did one side or the other not work?
-BrachI’m sorry about your Quaverato trouble. It’s weird that it suddenly stopped working.
There is a section in the troubleshooting guide that talks about this very topic (Appendix A). Work through that and let me know if you have any questions.
Good luck.
-BrachAlright everyone….
I just got done with the tutorial on tightening the treadle’s sweep. I updated both the Owner’s Manual and the Assembly Manual with an appendix called “TIGHTENING THE TREADLE ACTION.” Hopefully it’s clear enough and easy to understand. It describes the easiest way I’ve found to get a “stiffer” action in the treadle.
FYI…the original, bigger Ernie Ball volume pedals don’t have the tension washer on the axle so they depend a lot more on the string to get the proper tension. I have had success installing some tension washers on these volume pedals…after this washer mod they work great with excellent treadle stiffness. This has to be a consideration if/when we release this VPM-1 mod for the original sized Ernie Ball volume pedals.
-BrachOk, good work. Look at the solder side of the board to make sure all the solder joints are solid and there aren’t any bridges on that side (i’m still thinking uC pin 13 could be bridged).
Let me know what happens when you fix those connections.
Good luck.
-BrachYes, that is very odd…unlucky pins and all.
You are doing those continuity tests with the power off, correct? Are you sure your meter’s battery is good and it’s working correctly?
Are you referring to the “power led” or the “bypass led”… when you said it is connected to pin 13 of the microcontroller?
With the opamp…that is very unusual that pin 13 isn’t connected to the board somehow. With the power off, do you get continuity between pin 13’s pad and pin 13 on the IC? If not, try soldering the pin to the top of the baord. Do you get continuity between the pad of pin 13 and the pad of pin 14?
Lets try some higher order logic…When you test the relay connections as per the troubleshooting guide (5-C), does it appear that the relay is working as it should? (do this test with the power on so you can switch the relay).
Let me know what you find.
-Brach…about the voltages on pins 8 and 9…make sure you are able to get a resistance reading across the gain trim pot (TP5 and TP6), because that’s the only thing the separates those pins. Just make sure the gain trim pot isn’t open (not connected).
Pins 13 and 14 are connected so they should be the same voltage. Please re-check this.Trilby,
It seems like you are, but i just wanted to make sure that you are working through the troubleshooting guide…correct?
The red LED beside the bypass foot switch should be dark when the pedal is in bypass, and bright when the effect is engaged…is this correct or is it backwards?
Just follow the steps in the troubleshooting guide and let me know where you get stopped.
Good luck.
-BrachScooter,
Are you referring to the same noise that others in this thread have had…the high pitched whine, in which the frequency is affected by the rate knob and completely disappears when the depth knob is fully counter-clockwise?
I’m pretty sure this noise as a function of where the pedal is in the chain doesn’t have anything to do with an impedance matching issue. At least i can’t imagine how it could. This version of the pedal (8.2) has a very high input impedance and a low output impedance, so theoretically it should fit into an effects chain very nicely. I think it may have more to do with the power configuration of the pedal board. You could experiment with different pedal power wiring (like putting it at the beginning of the power chain), but it’s best to put the Quaverato on it’s own power circuit because it draws a decent amount of power (over 50mA). It’s usually fine to share power with pedals that draw very little current, but you can run into noise issues when you share power between higher current drawing pedals.
If you can’t find a decent power configuration that helps then the next step is to try putting a 1uF cap across pins 7 and 8 as described in post #25415 above. This seems to have cleared up this issue for at least a few people.
I hope this helps. Good luck.
-BrachI have a tutorial that i’m working on that describes how to tighten the treadle on these VP Jr pedals. I’m hoping to have it done within the next 2 weeks. Sorry it’s taken so long to get it done. My work schedule has suffered from this pandemic. Anyway, the process is pretty easy, you just have to take the whole pedal apart so it takes some time. I’ll post on this forum again when it’s done.
-BrachThank you for pitching in on this, cth515. It does make sense that decoupling the “noise making device” (the microcontroller) better would help cure the noise…although I’m pretty sure that I tired this with the noisy unit that i had and it didn’t help…but i was using a lower capacitance (around 220nf) so it makes sense that a much higher capacitance would make more of a difference. The board version shouldn’t make a difference of how well this works. The ground planes and power distribution path are very similar on both board versions. The ground planes are separated (digital and analog), but there are other ways for current to get through.
I’m really glad that you found a solution that works for you! Good work!
Mike353…yes, please go ahead and try this. The cap you linked to is much too large of a capacitance…use one of these:
https://www.taydaelectronics.com/capacitors/electrolytic-capacitors/nichicon-1uf-50v-105c-radial-electrolytic-capacitor-5-11mm.html
https://www.mouser.com/ProductDetail/KEMET/ESL105M100AC3AA?qs=HXFqYaX1Q2x0RWu%2FYCFzZA%3D%3D
https://www.digikey.com/product-detail/en/rubycon/50YXJ1M5X11/1189-1421-ND/3134377
Ideally you want a cap with a relatively low ESR (equivalent series resistance) which gives the noise a low impedance path to ground, but i’m not sure how practically important that is in this application.
Here is a page with a graphic of the Atmega328p IC’s pinout:
http://www.learningaboutelectronics.com/Articles/Atmega328-pinout.php
You can see that pin 1 is near the divot on top of the chip. Pin 1 is also closest to the dot on the IC (although it’s not shown in the graphic). Pin 1 also has a square solder pad, where as the rest of the pins on the IC have round pads. From pin 1 count the pins down to 7 and 8. Please note the graphic is a picture of the IC from the TOP, but you will be soldering the cap to the BOTTOM of the IC, on the solder side of the board. So keep that in mind when finding pins 7 and 8 on the bottom of the board.
Once you think you’ve found pins 7 and 8, test them to make sure you are correct. Pin 7 should be connected to the other 5v pins around the board and on the voltage regulator. Pin 8 should be connected to ground.
Remember electrolytic caps are polarized so the positive lead (the long lead) should be soldered to pin 7 (aka 5v) and the short lead (the negative pin, with the white stripe on the body) should be soldered to pin 8 (ground).
Cut the leads short and lay the body of the cap down on the solder side of the board so the leads are touching pins 7 and 8…then solder the cap leads to the IC’s solder pads. You may want to hold the body of the cap to the board with some hot glue or something to keep it from rattling around so the solder joints don’t eventually break.
Please let us know how this works for you.
Good luck!
-BrachJust to be clear, since your pedal is out of phase with itself…when the red led is on you do not hear the tremolo and when the red led is off, you do hear the tremolo…Correct?
The tremolo is supposed to be heard when the red led is on, and the effect is bypassed when the red led is off.
I’m not sure how the bypass switch could be out of phase, so let me know if this is the case.
-BrachThat’s great! I’m glad you are enjoying your VPM-1!
Please spread the word…we can use as much promotion as possible!
Thanks for the feedback.
-BrachWell that was an easy fix! I’m a little hesitant to say it’s totally good because it may start doing that again because we never found out the cause…but for now i’m glad it’s working well.
Take care and enjoy your Quaverato!
-BrachThank you for checking that. What you are saying is essentially that the resistance across R9 is 11K. The power was off when you measured this, correct? Can you please double check to make sure R9 and R10 are really 100k.
Also, please turn all the dip switches to the off position and re-measure the voltage on the opamp pins (when the power is back on).
Other than these things, please use your magnifying glass to look for little solder balls or other things that could cause shorts on (both sides of) your board.
Let me know about R9 and 10. If none of these things solves the issue then you might want to move towards replacing the TL074.
-Brach
