# HELP! Beginner Question CEM3340 VCO

**URL:** <https://lookmumnocomputer.discourse.group/t/help-beginner-question-cem3340-vco/444>\
**Category:** Uncategorized\
**Created:** [March 26, 2020, 12:35pm UTC](https://lookmumnocomputer.discourse.group/t/help-beginner-question-cem3340-vco/444 "2020-03-26T12:35:14Z")\
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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:** [March 26, 2020, 12:45pm UTC](https://lookmumnocomputer.discourse.group/t/help-beginner-question-cem3340-vco/444/2 "2020-03-26T12:45:34Z")

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Depends on the jack. The extra pin is probably a switch but there are many configurations (see [this post](https://lookmumnocomputer.discourse.group/t/can-i-add-1-4-jacks-to-this-eurorack-module/371/6) for some examples, and the linked document there for many more) and no standard pinout even if you’ve identified the jack type.

Do you have a datasheet for the jack you’re using?

Otherwise, plug in a cable and use your multimeter’s continuity tester to figure out what’s connected to what pin.

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