-------------------------------------------------------------------------------- CONCERTMATE MG-1 LFO RATE MOD ***PURPOSE*** This document contains instructions for a modification to the Concertmate MG- 1 synth. This mod gives the user a choice of 3 speed ranges for the lfo rate: normal, 1/2 speed, and 1/4 speed (approximately). It requires soldering and drilling a hole to mount a switch. I don't have any way to make schematics or take pictures, but this is a pretty easy mod and I don't think you'll need anything like that. ***MATERIALS*** Go to Radio Shack (or your parts supplier of choice) and get the following: spdt center off toggle switch 10uf capacitor (polarized, rated at least 16v) 22uf capacitor (ditto) wire (if you don't have any just lying around) The size of the capacitors can vary depending on how much you want to slow the lfo down. I chose the 10uf and 22uf caps because they were the closest readily available values for what I wanted to do. The value of the original cap in the MG is 6.8uf. When the 10uf is added to the circuit in parallel, the total capacitance is 16.8uf, which reduces the speed to 41% of normal. When the 22uf is added, the total is 28.8uf, which gives a speed of 24% of normal. ***PROCEDURE*** - UNPLUG THE SYNTH!! :) - Open up the MG and remove the top cirrcuit board (where all the sliders and knobs are located). - Locate capacitor C25 on the board youu just removed. It is located a bit to the left of the Auto Contour Trigger switch. This is the discharge cap for the LFO circuit. - Solder a wire to the negative (-) endd of C25. Solder the other end of this wire to the center contact on the spdt switch. Make sure you have enough wire to reach your intended mounting location for the switch! Insulate the connection with electrical tape or heat shrink tubing. - Solder the negative(-) end of one of the capacitors to either of the open contacts on the switch. - Solder the negative(-) end of the seccond cap to the remaining open contact. Insulate the connections with electrical tape or heat shrink tubing. - Solder a wire to the positive(+) sidee of C25. Solder the other end of this wire to the positive lead on BOTH caps at the switch. Insulate the connections with electrical tape or heat shrink tubing. That's all the connections that need to be made. Check for shorts and bad connections and put the top circuit board back into place. Then give the synth a test run to make sure the mod works as it should. The final step is to mount the switch. The location is really a matter of personal preference. I was going to put my switch right next to the rate control slider, but I wasn't sure if there was enough room there to install the switch without having it touch the circuit board. I ended up mounting it on the flat ledge to the left side of the keyboard. There's plenty of clearance underneath, and it's not used for anything else, so it made an ideal location. The switch is out of the way, but easily accessible. Just use a low speed drill so you don't burn the plastic. ***CONCLUSION*** Re-assemble your MG-1, and bwoooooooOOOOOOOOOOOOoooooooooowwwwwwww.... :) Enjoy!