MS-20: PWM CV In and Passive 4X Multiplier

Im not sure, but I'm pretty sure all this would void your warranty.

 Opening the MS-20 mini is fairly simple:
          Remove the 6 screws on the back
          Take caution and remove the black coated metal clips holding in the beads
          Gently remove the 2 cables from the jacks
          Now you can remove the back completely and work inside 

To install the PWM CV In jack:
         Locate the test point labeled TP-13
         The three pins above the test point are the potentiometer pins for the PWM knobs. 
         The pin directly above the test point is where you want to solder the wire for the PWM CV In.
           Locate a ground via like the one pictured below. Solder a ground point to the via and solder a                wire to it.
      Solder the two wires to a jack as shown below
Now you have a Jack to send in CV signals to control your pulse width's modulation.

The Passive 4X Multiplier is simple:
Solder 4 jacks together. Same pins on each of the four. You can do as many or as little as you would want.




Many more to come!!

13 comments:

  1. This is really cool! Thank you for showing me how to do this! That was one of the major things I wanted out of my ms-20 mini.

    Much love~

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  2. Thanks! Nice and clear, ideal for dummies, you really make our lives easier, thanks! If you are into moding your MS-20 and look for ideas, I got some :P Some of them already been done on the old version of course.

    -switch on/off between EG2 and VCA to remove EG2 from affecting the VCA instead of adding to ext in
    -CV in to control the LFO speed, let's say with an envelope.
    -CV in to control LFO waveform, let's say an envelope
    -2 CV in to control peak value HPF and LPF with an envelope
    -an LFO speed ext sync switch usable with the USB/Midi in

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  3. Hi! good job there... thanks for sharing your mods. gonna try pwm and cv split mods for sure.
    i have a question
    isn't the impedance affected when you connect 4 jacks together and split the voltage into 3 different destinations simultaneously? don't you lose voltage (and modulation width or something?)

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  4. Is there anywhere on the front panel (rather than the top or back) where the pwm jack could go? Just wondered before I remove all those knobs and sockets! If not I shan't waste my time. Thanks for a superb walkthrough. I have it working beautifully.... but just curious about a better location for the socket....

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    Replies
    1. I don't think there is enough room between the PCB and the panel to fit a switch; the two are so close together.
      But I honestly wasn't really looking too hard for a location to do that.

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  5. Can't get it to work... Hmmm... Red cable to female jack pin, and ground to female jack case (-)?

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    Replies
    1. Yea, that should work. Send me some pictures and I can maybe see what's wrong: oren@auxren.com

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    2. Nevermind! Just bad grounding.. My mistake. Thanks for a great mod! Really comes in handy!

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  6. Hi, it seems you have to use a Switched Jack for the PWM in, otherwise the Waveform pot stops working... anyone had this problem?
    thanks

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    Replies
    1. No, I just made the modification today with a regular jack and the pot still works. Thanks Auxren by the way for this great mod!!

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  7. What about build a custom side panel to put there those extra holes and switches??? What about doing two wood side panels

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  8. I know that you was very happy to create this website, so I agree with you. Be well!

    ReplyDelete