# Need some help with the kosmo vco w/ tuner. Please! I’ve lost weeks

**URL:** <https://lookmumnocomputer.discourse.group/t/need-some-help-with-the-kosmo-vco-w-tuner-please-i-ve-lost-weeks/691>\
**Category:** KOSMO MODULES\
**Created:** [April 21, 2020, 8:59pm UTC](https://lookmumnocomputer.discourse.group/t/need-some-help-with-the-kosmo-vco-w-tuner-please-i-ve-lost-weeks/691 "2020-04-21T20:59:17Z")\
**Posts on this page:** 1\
**Showing post:** 45

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**Author:** ![fredrik](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/fredrik/32/682_2.png) [@fredrik](https://lookmumnocomputer.discourse.group/u/fredrik)\
**Post date:** [April 24, 2020, 3:39am UTC](https://lookmumnocomputer.discourse.group/t/need-some-help-with-the-kosmo-vco-w-tuner-please-i-ve-lost-weeks/691/45 "2020-04-24T03:39:47Z")

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> [@Jos](#):
>
> Now use the middle point of the potentiometer as the signal you want to insert into the CV-in.

That’s what the coarse tune (center note) does already, though, so you could debug things the other way around – measure the voltage ~~at pin 15~~ at the potentiometer output, on the potentiometer side of the 100k, and tweak the center frequency trimmer to see if it changes.

If you cannot get a tone out of the chip with the available knobs/trimmers (there’s three of them on board that feeds directly into the CV input, before you even plug anything in), something’s broken. See [here](https://lookmumnocomputer.discourse.group/t/noob-question-about-first-diy-vco-module/506/27) for suggested trimming order.

 ![image](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/2X/e/eec43483dac6de40281c84b3de7ff2caf114dd3c.jpeg)

EDIT: Pin 15 is a summing node that’s held at 0 V by the input stage, so the input voltages are on the opposite side of the 100k resistors.

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