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So I’ve built almost 30 of these, and I can’t say all of them were easy. I find some strange problems with these every now and then. I do my best to get every resistor and cap perfect, soldering as best as I can, wiring as accurate as can be, quality chips.
Problem: When depth is maxed on this pedal it sounds fine and then the modulation dies. I get a basic signal with no chorus. This is only at max depth setting on the b10k pot.
Also, the same thing happens if I do happen to get a max setting on depth and no cut out – but the rate knob decreases. So basically, if I have max depth and the rate knob is lowered, it cuts the modulation out again.
Such a weird issue. Pulling my hair out trying to find what is causing the problem.
Next step is pictures/voltages but I’m so damn busy trying to complete client pedals that I barely have time to get it all uploaded here etc. Just curious if anyone has encountered this issue before.
I’m praying I won’t have to refund this person, I have a 2nd board (for another client) that I am moving in to try and replace it tonight. Fingers crossed.
I’ll do a breadboard video of it isolated tonight so anyone can see what it is doing. Sorry for not providing pictures or voltages, yet. I know that will be the first thing anyone asks me to provide.
Thank you in advance for any help!
Reviewing the schematic, I can propose that you may try adjusting the value of R29 (39K) slightly upward. This would decrease the level of the signal feeding the 4047 chip at the expense of a bit of depth but may prevent that problem from occurring. What i think is happening is the slight variances in tolerances of components. Since you have built so many of these, you are probably the most experienced builder of this circuit! As you state, we must assume that your builds are completely accurate with no solder errors or incorrect component values. Therefore, the only other possibility must be defective components or components that are out of tolerance. If you do find another explanation or component error, please advise the forum
I think I got it!
Went through my substitute list as usual and found something in one section that can affect the depth knob. R24 was 150k instead of 120k, when a better substitute is likely 100k ( I don’t have 120k usually ). Put the 100k in and the knobs are functioning perfectly. Could that be something that would affect the depth operation? I wonder if another dead board in salvage from the past had that same issue. Great find here.
I’ll keep trying it out today and see what happens.
Really helps when the guy I’m building for is patient! Thank you also Wilkie for your fast response as usual.
Go ahead and mark is as fixed Barry! Thanks my dudes!!
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