ms-20 modifications

JunoMan hbcsc349 at
Wed Sep 25 18:15:41 CEST 1996

I saw a PWM mod posting on music machines for the MS-20.  It's not that
detailed, but it's a starting point.


On Tue, 24 Sep 1996, DJMaytag wrote:

> i've finally gotten around to opening up my ms-20 and i've been thinking
> about adding some extra patch points and a few other things to it, more so
> now that i see how much space is available inside the beast (you could fit a
> body in there the thing is so big). i'm not exactly sure how to do
> everything i want to do, so i've got a few questions.
> first big question: there's a big metal (aluminun?) bar across the top of
> the circuit board. is this a heat sink of some sort? and does it HAVE to be
> there? sorry, i guess that was two questions.
> anyway, these are the things i want to add:
>         VCO1 audio output
>         VCO2 audio output
>         ENV2 CV output
>         VCO1 PWM by LFO (a la ms-50) input (is this even possible?)
>         LP VCF audio input (input between the HPF and LPF)
>         and an extra input (w/ amount knob) for the filters and VCO's
>         i'd also like to mod the speed range on the LFO, if possible.
> anyway, i'm ordering the schematics tomorrow, but even with the schems, i'm
> not exactly sure how to add/mod these things. i'm sure the VCO audio outs
> would be no problem, just do 'em like the 606 indy outs, right? it seems
> like the outs wouldn't bee too much of a problem, but the ins are what i'm
> not exactly sure about. if anyone has any advice or experience they'd like
> to share, i'd greatly appreiciate it.
> thanx,
> mitch
> djmaytag at
> three things to remember about me:
> 1) i'm not a dj, (but i play one on TV)
> 2) i have no intentions of becoming a dj, (or an actor)
> 3) i'm not a washer and dryer repairman either
> how's my posting? see http:\

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