Hi all, does anyone have any guidance for initial steps for debugging a 1222 that makes no noise? Stuff I’ve done so far:
*Double checked that I didn’t miss any parts
*Checked my solder joints - they seem good
*I’ve powered it up with no chips and checked voltages - all seem correct
*I set the ref voltage to 4V
*poked around the pins of the CEM3340 with my homemade audio probe do-hicky and got nothing
Thoughts?
Did you adjust the tuning pots? If the center is super low it won’t make much noise
Hi CTorp, good call. I tried turning up the CNTR trimmer and I started to get output - just clicks. The clicks sped up until the trimmer topped out. Clicks are about 1 second apart. Turning the TRK trimmer up also caused the clicks to speed up further, to about 2 per second. I noticed that fiddling with the connector for the rotary switch causes it to do weird chirps and sweeps. Bad wiring or poorly done molex?
The clicks should be the bottom end of the pot. Slowest oscillation. Something must be not right. Check the voltages coming off the rotary? Should be 4-3-2-1-0
Clicks are good! as mentioned its the low end of the OSC. The thing we hear as tone is actually perceived as rhythm when it is slow.
I have only built the stripboard version, but they should be similar enough.
Is there a Course Tune you can tweak to see if it becomes a tone as you pitch it up?
Have you connected anything into the 1v/oct input like a keystep or other controller?
Those are indeed the voltages I’m getting off the rotary.
Got it working. Just needed to re-seat the pins in the molex connector for the rotary switch.
Nice! Good to hear. I built three and one of them put up a good fight
I’ve done 2. 1 more to go!
Hello all, 1st post. Can I use 2.2k resistors in place of 2k? I’m out of 2k at the mo.
The only 2k I can find are for the LEDs, so that shouldn’t be a problem at all.
(You can go both up and down here, the only thing that happens is that you get a slightly different LED intensity. The Nano might start having opinions if you go below 200 ohm or so, though.)
Great, Thanks very much, I’m on a learning curve!
Hi all,
After sourcing most materials to build the 1222 VCO, and beginning the build process, I realised I accidently ordered the wrong jack sockets. Instead of 5 pins, they have 3 pins. As a consequence, I cannot attach the sockets to the secondary PCB. Therefore, I am considering leaving off the secondary PCB, and connecting the sockets via a Molex connector to the main PCB. The main PCB and secondary PCB connect with a header with 12 pins: 8 for the live sockets, 4 for ground.
Thanks for any advice!
hey synthesis! oh I see!!! thats a bummer! not too worry. yeah just follow the schematic with the pinouts it looks like you have done! just connect all of the sockets to the ground via a big bare cable should do the trick! it doesn’t matter what ground they are connected to aslong as they are connected 
so yes you can do what you mention!
Thanks Sam!!
Keep up the good work! I am already looking forward to your next module of the month! 
Is it normal that the triangle wave output is much much quieter than the other two outputs?
Yeah that’s a trait of the 3340 chip. The saw is about 66% volume of the square and the triangle 50% or somewhere abouts @hiegdk
38% and 76%, typically 
(but the relation between peak voltage, average electrical power (rms) and perceived loudness is complicated enough that you probably want to attenuate your way out of this anyway.)
