this troubleshoot guide applies to POM-400 and POM-170. POM-16 does not make any sound on its own. follow this guide and you'll have sound in no time.
it is recommended, especially if you are new to patching, to simplify a patch to troubleshoot it. for example, if you have a large patch and something goes wrong where you can no longer hear your sound, try removing some of the cables. the easiest way to figure out what is going wrong in your patch is to start at zero, and slowly work your way back up so you can check each part of your signal flow. start with the oscillator going to the vca, and the vca going to the speaker left/right in. turn your tune knob and pwm knob slowly, to get a feel of the audible ranges.
no sound from oscillators
when trying to troubleshoot a patch that doesn't make sound, or has lost sound from the oscillator we have to consider two knobs in particular – the tune knob and the pwm knob.
saw or sine
make sure the tune knob is turned to around 12 o'clock, or half way through the range of the knob. the tune knob is responsible for the pitch or frequency of our sound, and can be pushed either below or above audible range. little turns of knobs on modular synthesizers make a big difference. try turning slowly and listening carefully to the range you have on your oscillator, so you get a feel for where it can be heard and what frequency is where.
start with the pwm knob turned all the way to the left, or the starting point of the knob range. this is because pwm, which stands for pulse width modulation, lengthens and shortens the pulse width of your wave. depending on where it is, and where your oscillator tune knob is, the sound may be pushed out of audible range. turning the pwm knob up will increase the range of modulation, which is desirable at different times, and especially fun with a cv into that jack. pwm can add complexity to sounds where you have only one oscillator, and it is especially useful for simulating string sounds.
if you had sound from your oscillator before the filter, and it goes away after being run through the filter try slowly turning the frequency knob all the way to the right. you can try slowly turning left and right and listen if you can hear a difference in the sound coming through. depending on the frequency of the signal coming from the oscillator, you will eventually find a compatible range. when the knob is turned all the way to the right, the filter is letting through most of the incoming oscillator signal, barely cutting off or filtering any of the signal, which gives you the best chance of hearing the oscillator, regardless of its frequency. it's important to know that when the oscillator 'tune' knob, or the frequency of the oscillator changes, you will be left with a new range to work with on the filter frequency knob as well.
the resonance knob can start at all the way or almost all the way to the left, or starting point of it's knob range. you can try turning the resonance knob up with different positions on the frequency knob, to get a sense for the additional high frequencies that your resonance knob will be able to pull out, depending on your root pitch. try turning the knob slowly and fully on a few different frequencies, so you start to get a sense of the ranges you have to work with.
once you can hear your oscillator, you can add in the filter by going from your oscillator out into your filter in, then from your filter out into your vca in and the vca out into the left/right in of the speaker. if you could hear your oscillator okay before, but not now, then you know you have to adjust the frequency knob on the filter, and the resonance. once you have your audio path is secured, you can start to add back in your lfo's and gates, one at a time, to note the affect it has on your patch. the more modules and cables you combine, the more complex your patch or signal flow is, and the more likely it becomes that something moves out of the desired range.
don't give up! it's similar to learning a guitar, clarinet, or any other instrument, where you sometimes lose your ability to sound out for a second. you can do it!