How to Circuit Bend a Casiotone MT-52

By turning the trimmer pots in a circuit you alter their resistance.

Circuit bending is an experimental creative process involving the modification of basic sound-making circuits, such as those found in children's toys and basic keyboards. Casio keyboards are popular with circuit benders because of their basic and easy-to-modify circuitry. The percussion circuit in the Casio MT 52 has trimmer potentiometers. It's an ideal choice for a beginner "bender" because you can modify its sounds by adjusting the trimmers. Further modifications can be achieved by rewiring the circuit.

Things You'll Need

• Phillips screwdriver
• Mini jumper cable
• 2 Jeweler's screwdriver
• Wire
• Soldering iron
• Roisin core solder

Instructions

1. Unplug the mains power supply. For safety reasons, never attempt to bend a circuit of a mains-powered device.

2. Place the Casiotone MT 52 face-down. Place a pillow under each edge of the keyboard to elevate. This protects the 44 keys from being damaged when your unscrewing the back.

3. Remove the bottom of the keyboard and set it to one side.

4. Carefully unscrew the circuit board and pull it out from the Casiotone MT 52 as far as the wires will allow.

5. Flip the keyboard over and position the circuit next to the keyboard. The wires are long enough to permit partial removal of the circuit board.

6. Adjust the position of the trimmer potentiometers on the percussion model. Hit one of the percussion buttons on the keyboard to activate the sound. Continue tweaking the trimmer potentiometers until you find a sound that you like. This is the easiest element of circuit bending a Casiotone MT 52 because you don't need to rewire any components.

7. Place the circuit board face-down.

8. Attach the mini jumper cable alligator clips to a pair of jewler's screwdrivers. Then press the tips of the screwdrivers against a random pair of connector pins. This "bends" the circuit. The art of circuit bending is characterized by a random and experimental approach, so the best way to go about this is to try out as many circuit bend combinations as possible. When you find a bend combination that you like, stop experimenting.

9. Solder a piece of wire between the two connector pins to permanently bend the circuit. This connects the two points of the circuit together and modifies the sound characteristics.

10. Wrap the wire running between the two pins in electrical tape. This insulates and reduces the chances of shorting out the circuit. Repeat this process for each combination of pins that create interesting sounds.

11. Reassemble the keyboard.

Tips & Warnings

• If you want the option to turn off a modification, solder a switch between the two selected circuit board points.

• Circuit bending will void your warranty.

References

• Anti Theory; Circuit Bending; How it Works
• Table Hooters; Warranty Void; Casio MT52
• Get Lo Fi: Space Adventure Keyboard Bending Guide

Resources

• Make Projects; Circuit-Bend Your Casio SK Keyboard; by Cristiana Yambo