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Yes, the LDRs are very sensitive to even the tiniest amount of light.
So by that test we now know that the high LDR is not shorted and it is working, at least on some level. Just to clarify, when you cut the high optocoupler open, did you see that the LED was pulsing at any time (or at any knob setting), or was it just staying on all the time? Because the pedal is behaving like it’s just staying on and never flashing, at least according to the symptoms that I’m aware of. If this is the case then there could be a problem with the mix pot. Please ensure that the center pin of this pot is scrolling from close to 0 volts to close to 5 volts as the knob is turned from one end to the other. Otherwise, there could a problem with Q1…ensure it’s in the correct orientation and soldered correctly, without any shorts.
-BrachIf you haven’t measured the resistance (with the power off) across the test points (1 and 2), please do that…just to ensure there is no short or near-short on those pins. There may be a short on a part of the board that isn’t visible.
To find out if the LDR is defective you can always measure the resistance across TP1 and TP2 (with the power off), while you shine a flashlight in the hole you made earlier in the heat shrink. I’ve never seen an LDR short out or go bad, so it’s probably not that.
-BrachThat’s really good information to have…the high side audio is not pulsing (thanks for the audio clip, that was very helpful). The other piece of good information to know is that the high optocoupler LED is working. So there must be a problem around the LDR, like it’s possibly shorted. So from looking at the schematic, make sure TP1 and TP2 (or JP1 and JP2) aren’t connected/shorted. You can use your meter’s continuity tester to check this (with the pedal’s power off).
Let me know what you find.
-BrachI’m glad to hear you are liking the Quaverato, but I am sorry about this issue.
It sounds like you may have some leaky optocouplers. It seems like light is somehow making its way into the heat shrink, causing the signal not to shut off all the way. Please make sure you seal the ends very well with some opaque substance (even poster putty/sticky tack will work). Also, make sure you optically seal the holes you made in the heat shrink.
You can use calibration mode to tell what side (high or low) is leaky. Also, it’s best to use the square wave setting with the depth all the way to 100% (fully clockwise) and the LFO rate set relatively slow, so you can easily hear if the sound is not shutting all the way off on each cycle.
Good luck!
-BrachRamin,
I’m sorry about this. I’m actually out of state right now on family vacation, but if you can send me an email with your serial number to info “at” zeppelindesignlabs.com I can get you the arduino source code. It may be a couple of days before i’m able to check my email again, but I’ll get it to you asap.
-BrachI’m sorry about the misplaced insulation paper. All it is, is thick cardstock paper (that won’t get punctured easily), so you can just use that. It wouldn’t hurt to cover it with a layer of electrical tape for extra puncture protection.
There is nothing special about the wire. You can use whatever insulated wire you have that will fit into the pcb holes. Don’t use thick wire that is hard to bend or barely fits into the pcb holes. Whatever wire you are using is probably fine as long as it fits that criteria.
Good luck!
-BrachIt seems like it’s all working correctly as you described. Is the pedal not sounding correct to you?
Remember the calibration values given in the manual are arbitrary values to just ensure the circuit is working more or less correctly, and by your measurements, it is. Keep the high trim pot set to whatever gives you the lowest value and then adjust the low trim pot until you like way it sounds. Make up for any low signal levels with the gain trim pot.
Also remember when you measure the resistance of the test points, you are measuring the LDR resistance in the optoccoupler while the LED light is shining on it, which the trim pot is controlling the brightness of (see the schematic). That is why the resistance is going up to megaohms/open when the light/power is off.
-BrachThat sounds like a very interesting product. That would be a very practical piece of equipment to have around.
To answer your question, yes the Altura has a powered midi jack.
Good luck with the Widi Master!
-BrachI’m so glad to hear you got it working again! Good job!
If you wanted to re-install C17 you might need to get creative with how you wire it. The original pads on the board are not able to be used so you you’ll need to run jumper wires from the cap leads to the output jack tip and pin 3 of Q3 (as per the schematic). But that’s only if the relay click starts bothering you. If not, just keep it as is.
-BrachExcellent! Great work fixing that. Now we can work on the original problem.
Yes, the place to start is with the optocoupler circuit. Right now, the only thing that i’m sure of is that the LED in the optocoupler’s aren’t lighting up. That could be caused by several issues. Let’s start with the voltage to that circuit. As you see on the schematic, R7 and R8 should have 5V on one pin. Are you getting 5V both or either of them? If not, this diagram shows the 5V rail to both those resistors:
https://zeppelindesignlabs.com/wp-content/uploads/2023/06/5v-rail-jpg.webp
If 5V isn’t getting to both of them then the problem is probably a broken trace or something between VR5 (the multiplier pot) and R7…assuming VR5 and VR1 (spacing pot) are getting 5V. If R7 and R8 aren’t getting 5V then run a jumper as needed from any 5V source, but preferably from C9 seeing that it’s close to the source.
Let me know if that works or not.
-BrachI’m glad you have confidence in your meter. Do you have as much confidence in your meter as in your ability to read it correctly (if it’s one of those analog meters)? I know for me those analog meters can be confusing.
I was referring to the relay continuity tests…when I was asking about power on or off, not voltage tests. Please let me know about this.
The voltage on R28 is of no consequence because C17 is removed.
The voltage on pin 5 of U2 is not off enough to keep signal from passing through that opamp.
If the optocoupler’s LEDs are not lighting up, then that would cause no signal to pass through the pedal when the bypass LED is on (when the effect is engaged). It would be unlikely that both optocoupler LEDs are not working, so are you sure this is happening? Either way, as I said earlier, you have more than one issue going on here because you are still not getting signal through the pedal when the bypass LED is off (the effect is bypassed). This is a much bigger issue than the previous one. The signal path is very simple in the bypass circuit….from the input jack tip, through the relay, to the output jack tip. If you are getting signal into the pedal and it really is not passing through to the output jack (when the effect is bypassed) then it can only be 1 (or 2) of 2 things: either there is a bad or broken connection somewhere (most likely a bad solder joint) or the relay isn’t working correctly. In conjunction with your meter testing this circuit, also please actually try it out with a real guitar signal (it’s important to try it both ways).
This problem (of the pedal not bypassing any signal) suddenly started when you re-flowed the solder joints and removed C17, correct? So it stands to reason that something you did in that process is causing this. Check all those connections that you touched up with the soldering iron. Make sure the input and output jacks are soldered correctly (re-flow them). Make sure the remaining pads (and traces) of C17 are not shorted to ground (see if the output jack tip is connected to ground…continuity test this). Is the relay really switching? You can test this with your continuity tester by following this image:
https://zeppelindesignlabs.com/wp-content/uploads/2023/06/relay-jpg.webp
The red lines represent the continuity you should have when the effect is engaged, and the blue lines represent the continuity you should have in bypass. Make sure you are testing the correct pins. This picture is taken from the top of the board, but it’s symmetrical so the bottom of the board is the same.
Please take the time to go through (and do) EACH of these things I’ve listed here in this post, until you find the problem. Let me know what you find.
-BrachAre you making these tests while the pedal power is off or on?
In your re-flowing the solder joints something must have changed…most likely something was shorted. Make sure that the pins of C17 aren’t shorted. You may just want to try it out with a guitar to see if signal isn’t making it’s way through while the effect circuitry is bypassed.
It seems like there may be several different issues that are causing these problems (or possibly inconsistent/intermittent test results). In cases like this we need to eliminate each potential issue in hierarchical order. The issue at the top of the list is your meter. You probably should wait until you get a trustworthy meter that can give you good results before you continue. I’ve used a few old radio shack meters before and from my experience they aren’t very reliable.
-BrachWow! You are quite a distance away from me right now. The internet has made the world such a small place.
Something might be wrong with your continuity testing. You said you were not getting continuity between the input and output jack tips when the bypass switch is off (which means signal will pass through your pedal when the LED is off)…but in your first post you implied that you were getting signal through the pedal when the bypass switch was pressed (when the LED is turned off), and then when the bypass LED is turned on, the signal drops in volume, unless I read into your post the completely wrong way.
Anyway, this makes me have a hard time trusting that your continuity tests are accurate. Could you please let me know if you are getting signal through your pedal when the bypass LED is off?
-BrachThat’s correct about C17 being in the same circuit as Q3. So if there are no shorts across the pins of C17 then Q3 is not the main problem. It is still not behaving correctly because of your voltage measurements, but that’s not the thing causing no signal to pass through the board because C17 is removed.
You are right, it could be the relay. Go through steps 5-7 on the troubleshooting guide (assuming it passes all the steps up to that point). If that doesn’t help you may consider following the steps in appendix A to see if the LEDs in the optocouplers are working correctly.
-Brach
