From s9506190@minyos.xx.rmit.EDU.AUSun Apr 30 13:10:09 1995 Date: Sun, 30 Apr 1995 03:29:18 +1000 (EST) From: Damien Miller To: map@cs.washington.edu Subject: MiniMoog PWM mods info Hi, Here is a text file describing a modification I did to my minimoog, you might like to put it on the archive site, alternatly this is available off my homepage (or more directly at http://minyos.xx.rmit.edu.au/~s9506190/minimoog.mod.html). Enjoy! Damien ------------------------- CUT HERE ---------------------------------------- DISCLAIMER: I, Damien Miller, make no guarentees that these modifications will work. Furthermore I take no responsability for any damage resulting from the installation, operation or consideration of these modifications. COPYRIGHT (c) 1995 Damien Miller. Free for private or noncommercial use. This document may be transmitted or made available on public access networks only if it is kept whole (including the COPYRIGHT and DISCLAIMER). MiniMoog PWM input modifications: Start by cutting these wires: pin 14 of osc 1 waveform sw to osc.brd connector B pin 22 (yellow wire) pin 14 of osc 2 waveform sw to osc.brd connector B pin 18 (white, grey stripes) pin 14 of osc 3 waveform sw to osc.brd connector B pin 16 (white, blue stripes) now make three holes in the top of the case, and install mini-phono sockets. I used switched sockets, with the tip going to ground when no plug was inserted. I made a CV inverter and mixer to make sure that the PWM inputs accepted 0->+5v CV signals (such as those from my in progress outboard LFOs), and also to protect my mini from any nasty zaps from the outside world. Here is a simplified asciimatic. >From wave switch From PWM CV in socket O O | 10k | | ---/\/\/\--- | | | | | | 10k | |\ | | --------/\/\/\--o--| \ | | | \ | | | |---o----- | | / | | 10k 10k o-----o--| / | |--/\/\/\----o----/\/\/\--o | | |/ 1/4 TL074 | | | | | | 10k | |\ | \ \ ------/\/\/\----o---| \ | / / | \ | To osc.brd 10k \ \ 10k | |----o---------O / / | / | | |----| / | | | |/ 1/4 TL074 o--o--o | | \ | / ----- \ 1k --- / - | | ----- --- - I tapped power off the wires leading to the oscillator board's connector A pins 18 (red wire, +ve), 17 (white wire, GND), and 16 (black wire, -ve). For those without a service manual the oscillator board is the one immediatly at your right when you open the rear of the unit. There are two edge connectors which this board sits on, the one on the right is connector A and its numbering is from right (pin 1) to left (pin 22), the one of the left is connector B and its numbering is also from right (pin 1) to left (pin 22). Pin 14 on the oscillator waveform rotary switch was a bit trickier to find, you could trace the wires leading from Con. B pins 22,18 and 16, but this may involve cutting cable ties. Otherwise pin 14 (on each switch) is at about 4 O'Clock, surrounded by a 1k resistor. Good Luck and Happy Modding! Damien Miller /-------------------------------------------------------------------------\ | Damien Miller a.k.a s9506190@minyos.xx.rmit.edu.au a.k.a Silicon Dreams | | http://minyos.xx.rmit.edu.au/~s9506190 || old addr: toado@swin.edu.au | | CAUTION: WEIRD LOAD | \-------------------------------------------------------------------------/