Saturday, March 6, 2010

Adding proper CV/Gate inputs to a Roland MC-202

For the final MC-202 modification in my little series, here's how to add proper cv/gate inputs. In the video I highlight the differences between the internal inputs (which are quantised by the cpu) and the modification.

This mod requires cutting traces, so a little extra care is needed. Be extra careful when working on the gate part since there's not much to solder to around the CPU. You'll have to scrape off some of the mask on the traces and wire direct to them. Take your time on this and be sure you have done it correctly before applying power to the machine.


  1. Thanks for the post! I had a few questions about this.

    It seems that if the original has the lag and quantize it's does really deliver anything better than the mod does. Once this mod is done, in what instance would you want to use the original CV/Gate in?

    Does it make sense to repurpose the two original jacks for this mod? Can the originals be used or must it use the switching jacks you mention?

    I just wonder that if the original CV/Gate becomes redundant whether it's just better to run the modded version all the time.

  2. the original ins were not ever intended for live use, their purpose was simply for entering notes into the sequencer from say an sh101 instead of using the keypads. So by permanently doing this you would loose that ability.

    with a clever bit of trace cutting you should be able to just add a switch and use the original jacks. Then you could toggle between them.

    So its up to you really, if you feel you dont need to use external input to the seq then there's your answer.

  3. Ok good to know. So it's really about external sequencer entry too. In that case it *would* serve some purpose with other legacy gear.


  4. better also keep the original.. allows you to do crazy stuff.

    AFAIK this mod is very unsafe.. there's no protection at all against wrong input signals, shorts, etc. This could fry the insides if you connect e.g. an 808 gate signal. You shoud use 2 diodes (shottky's) and a resistor or alternative protection circuit.

  5. i've used the 606 trigger outs to the gate in without problems and iirc they are pretty hot, +14v or something.

  6. Thats correct about the 606 trigger outs. That changes nothing about the fact that its DANGEROUS and you shouldn't do it with protection against over/under voltage and shorting..
    I wouldn't wanna risk frying the CPU. Accidents happen quicker than you'd expect.
    A lot of 303 cv gate mods (Acidlab Modular in particular) are also very unsafe because if the direct connection with cpu.

  7. i meant "because OF the direct connection with cpu"

    This is how you play safe with CMOS logic:

  8. sure but if you think about it, its on a switched jack, so when a cable is plugged in its disconnected from the cpu. There is the possibility of a ground short when the cable is plugged in i suppose. I have a ground lift switch on my jacks for this, but i often forget to switch it and have had no problems so far.

  9. if you dont hotplug it it wotn even be a problem ;)

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  11. Have one question - controlling via internal sequencer is still possible after the modification? Cheerz!