Did you try adjusting the trimpots? If they are way off you might only hear slow clicking.
Thanks! I will check this out tomorrow evening!
Based on measuring with a multimeter, all connections between components related to the AS3340 chip of the main oscillator are ok, including the links between the resistors you mentioned. But I have not tried measuring their voltages going in, so I will try this out.
Yes, I tried adjusting both trim pots related to the main oscillator several times, but it does nothing. Forget to add this to my previous list of stuff I have tried.
Hi ive just finished building this module but the audio is very very quiet hardly hear it at all, from what i can tell by turning pots etc there are changes to sound so seems to work but no real sound, is there anything obvious that i should check first so frustrating seems to be nearly there
i guess make an audio probe (a jack socket with a wire to ground connected then the tip of the jack.
have a listen and see which point it is broken.
i suspect its not working at the VCA. which is an lm13700 U7a
look at the schematic and treat it as a flow chart, test on legs of components following down from the oscillator to the mixer to the filter to the vca and see where the sound stops
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cheers will check vca
check the output of the mixer circuit of the oscillators first pin 3 of U6
to be doubly sure the oscillators are mixing together before the filter. then you in essenxe half the circuit knowin the oscillators andmixer work, and the issue must be in the filter or vca
I am not reading any voltage at pin 15 of the chip of the main oscillator, but also not at the secundary oscillator. Might be that I am using my multimeter wrong here. Especially since I now seem to get some sound out of the main oscillator after a lot of fiddling with the trim pots! And the tone chances when I twist the Mod and Envelope knobs, so the pin 15 seems to get variable inputs.
However, no matter what I try with the trimpots, I only hear sound from oscillator 1 with the tune 1 potmeter in the first 10% of its range. After the first 10%, I can no longer hear the primary oscillator. Could a wrong resistor value be the culprit? If so, which one(s) could be the suspects? Reading resistor bands is a pain, so narrowing it down would safe a lot of time.
Finally, a checking question: should the secondary oscillator always influence the primary oscillator, even when the second switch in the left row is set to VCLFO?
Thanks!
Pin 15 is a summing node at virtual ground, so you will not see a nonzero voltage there. To check the control voltages you need to measure at the other ends of the resistors connecting to pin 15.
I assume you mean the RV7 potentiometer:
If R24 were too small, like 2.2k instead of 220k, itâd make the knob pretty useless except in its top 10% or so. The bottom 10% behavior seems harder to explain. What happens in that first 10%? Does the pitch go from low to very high before becoming silent?
I donât have this module but from the schematic, it looks like the switch youâre talking about chooses between LFOOUT and VCLFOOUT:
LFOOUT comes more or less directly from the second 3340 oscillator and VCLFOOUT apparently comes from a voltage controlled amplifier whose input is LFOOUT. So yes, either way itâs being influenced by the second 3340.
Thanks for these additiinal leads!
Yes, the tune 1 knob is the RV7 fine tune 100k in the schematic.
I did some finer measurements at pin 15; I am reading voltages in around 0.04 Volts, which is way off from the 6-10 Volt you mentioned previously.
It seems to me as though something is sinking the current before it reaches pin 15.
Some additional tests makes me wonder whether the main oscillator is in fact making a sound, or whether it is the filter that is self resonating, as I only get a sound when the filter and resonance knob are more than 25% turned on. Is this possible, based on the schematic of this module?
First thing I want to do is check all resistor values, especially the one you (Analog Output) pointed me at.
Next thing I am considering is removing some resistors to isolate the problem; because all parts of the circuit interact in one way or another, it makes it very difficult to locate the source of my problem. Does this seem wise?
Repeating myself:
Zero volts is exactly what you expect. You canât check the CV by measuring voltage at pin 15.
And:
Thanks for your input. I misunderstood you previously: I believe I have some reading up to do regarding âsumming nodes at virtual groundâ, as I have no idea what this means. 
I will do some more tests this weekend regarding the pitch height.
I am reading around 0.018 Volts at R22/R26/R24/R10/R9 on the side connected to pin 15 of the AS3340 chip. Does this seem right?
It turned out it was not the main oscillator I was hearing, but the secondary oscillator as the Mod knob RV18 was turned on. 
And I hear the secondary oscillator only when the Tune knob RV7 associated with the main oscillator in the first 10% or so. The pitch is slightly going up, but it is not very high when it stops making a sound.
I was not expecting this module to give me any problems, because of the spacious layout and all the standard components, but it is really testing my persistence. 
See my previous answer.
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no or very little sound from module, thought i had found issue transistor Q1 not showing any voltage all other 2N3906 around 10v replaced it but still not showing any voltage, transistor Q4 2N3904 also not showing any voltage ?
I feel so incredibly stupid: Turned out I used some resistors with incorrect values!
For the 2x 220k, I apperently used 47k resistors. And the 3x 24k resistors were in fact 200k resistors. I have bo idea how that could have happened. Maybe late night building turned out to be too late�
After replacing these five resistors, everything seems to work properly!
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@lookmumnocomputer any indication when these will be back in stock? Thanks!
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within 2 weeks 
hope that helps!
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the 2n3904 is the noise. check the schematic to see the functions of the different components.
have you tried the probe yet? testing at the diffeent points? testing the oscillators first and seeing if there is output. then testing from the mixer, then the filter then the VCA this will aid finding which part is actually not functioning.
Nice module. Finished building it and now playing and having fun with it. Thanks for creating it Sam. 
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