From: Carl Virtanen Subject: Modding the Realistic Moog (mg-1) Hey there! Well, thanks to Mark Glinsky for passing along the schematics, i was able to finally take the plunge and do a mod on the Moog mg-1. I'm not sure about the rest of you, but doing that first mod, ie-sticking your soldering iron in there and hanging on for dear life, can be a very nerve racking experience. Especially when it's that precious little analogue jewel you can't afford to screw up on. Anyways, it was a simple mod so relatively painless. Hence, i'm passing along the info for other mg-1 owners: External source filter input mod for the moog-mg1 (realistic) What you need: soldering iron phillips screw driver knife solder 0.1 uf capacitor short length of wire Carefully remove the case to the mg-1 by unscrewing the screws on the bottom and the one in the bottom, middle, back side. This should allow you to tilt up the case to expose the bottom of the main circuit board. You'll have to take this board out as well by removing the 5 screws that secure it in place. Make sure you remember to take the knobs off on the front of the synth and be careful with the foam dust covers inside as they fall apart easily. LocATE the level sliders for tone source1 and 2. In between these, you should see a polarized capacitor (c14). Locate the (-) negative pole and turn the board upside down to expose the solder joint. You'll want to connect one end of your wire to this point on the circuit board using some solder. The next step is to connect that wire to the external input. Now, instead of drilling a new hole, i used the right aux in from tape. To be quite frank, these inputs are kind of ridiculous in the first place, as they are only useful if you want to put your stereo through and play accompanying music to James Last or perhaps Santa Claus plays the Moog (one of my faves!). Most people will probably not miss this... ;) So the next step is to locate the circuit board where these inputs and outputs are inside the mg-1. Don't bother removing the board as it's riveted in. Locate the right aux input on the back of the board (should be the one on the far left). You should see where the centre of the plug connects and traces up and to the left and the outside of the plug connecting to the common ground: \ <--Using the knife, gently scrape away the trace here to sever the \ connections from the positive centre of the plug to the outputs. | |\ | | 0 <--Next, solder one end of the capacitor to the positive (centre) part of the plug. Connect the other end of the capacitor to the wire you soldered on the main board. The nice part is that the connector is already grounded so you don't have to do any more work! Reassemble the beast and connect a line level input to the aux in. You should now hear it going through the filter! Great for shortwave, didgeridu's, or 808 toms! Hope this makes sense to everyone. Might be a bit much but i tried to write it with the novice in mind. Good luck, and all the usual disclaimers apply... Ie-proceed at your own risk! Oh, and make sure you unplug it before doing all of this ;) carl From majortom@muc.de Thu Apr 25 12:11:08 1996 25 Apr 96 15:10:59 +0500 25 Apr 96 08:08:42 +0500 From: majortom@muc.de (Michael Wesemann) Subject: Re: Joining the growing hoard of MG-1 users Date: Thu, 25 Apr 1996 13:20:23 +0200 Organization: mw References: <199512172004.MAA24759@taz.hyperreal.com> From: David Johnson >It's not very flexible...unless I route it through my Quadraverb... Don't be deceived by it's appearence. The MG-1 has a surprising bandwith of sounds. >Is the MG-1 truly related to the Moog Rogue... In my opinion it is superior to the Rogue because of it's crossmod/ ringmod function (I don't know which it uses) labeled "Belltone". The MG-1 suffers a bit from it's cheap manufacturing. I've found it's output signal quality is higher when using the headphone jack on the front. For those who performed the filter input mod the following might be of interest: after modding a friend's MG-1 this way I found that the signal I put through lacked a lot of bass and had too much high's instead. In my case the cause was the capacitor used in the mod. Together with resistance from elsewhere in the circuit it acted as a highpass filter which filtered out large portions of the bass. After removing the cap the signal was just as I'd expect from a Moog filter... Also it behaves in a very musical way when overdriven which imo is another very typical aspect of Moog filters. Though it's very different to an overdriven Minimoog filter, for me the family resemblance is still obvious and I could imagine some instances where I'd prefer the MG-1's overdrive which in my ears is a bit less "brutal". ________ michael __________________________________________________ http://www.muc.de/~majortom/analogue/amusic.htm Date: Thu, 7 May 1998 13:38:17 +0200 (MET DST) From: Lothar Bittner To: analogue@hyperreal.org, ddwagner@chatcarleton.ca Subject: Re: Mg-1 Input mod -what da smeg? Hi, > > I was reading the posts in the AH archives, I'm about to > do the inpute mod myself, and am very curious about the extra 0.1 > capacitator's function? Did anyone ever find out what it was for? > Someone in the archives was mentioning that they did the mod without it, > but there was no reply to his message saying if that was ok or a big > no-no! Well, since you spotted the archives already, I had the same problem last August, and started a small discussion on AH regarding this subject (the mails were about "Concertmate MG-1"), and Paul Schreiber advised me to use a 0.47mf capacitor instead of the 0.1 one mentioned elsewhere. The reason for it was, that the 0.1 cap takes away some bass (it forms a passive filter with some other components of the MG-1), and the 0.47 cap does not, but still protects the input from DC coupling. Or something to that effect. For technical details refer to the archives, for installation instructions - feel free to ask me. Oh, and yes, I did the mod, first without any cap, then with the 0.47 cap. No directly audible differences to me... both seem to work, but the mod with the cap is safer perhaps? Lothar