No please!

Years ago, I started building this kit, and was never able to get it working because I had a problem with 5v shorting to ground. Was never able to figure it out so I put it aside. Here’s the thread on it:

Came across it recently and decided to give it another go. So I was actually able to find the short! I’ve successfully checked all the voltages in the troubleshooting section and they all look good. Now, the unit powers up successfully. I can adjust the LFO speed and see the LED reflect that change. I can start/stop the sequencer, and get some drum beats going. However, I can’t get the VCO working properly. I did the signal troubleshooting, and points E, F, G, H, I, J are all silent.

Strangely, I can get some sound under the following condition: sub-oscillator switch in bottom position, sub level all the way up, and filter mode switch in the low pass position. In this case, when I hit run/stop, I do hear an oscillator going between two notes (although very quietly…I had to turn the input up quite a bit on my audio interface to hear it). Changing the glide knob applies glide to the sound, and changing the octave/master tune has an effect as well, so it does seem like I’m hearing some kind of oscillator. When this is running, I can also hear the sound at output K (mixer out). You’d think this is the suboscillator I’m hearing, but even when this is occurring, I and J (and all other osc outs) are silent! Playing with the filter doesn’t seem to have any effect either, and I can’t get it to self oscillate.

Really confused about where to go from here to continue troubleshooting. Any suggestions?


Oops, I’m dumb. I’m hearing the digital oscillator. So that signal works, and appears in the mix out pin. But filter signals are quiet, as is the VCO.