Electronic keyboards, especially analog synthesizers, occasionally develop keys that do not produce sound, also known as “dead” keys. Most times, dead keys are due to dirt and other debris disrupting the signal that creates each key’s designated tone; cleaning these contacts will solve the problem. Understanding how to maintain two distinctive but very common designs, the Casio SK-1 “button contact” design and the Moog Satellite “rail contact” design, will solve the problem in most cases.
Cleaning the contacts of a "button contact" design - Remove the plastic back enclosure of the keyboard; there are several small Phillips head screws mounting it to the top. Although these directions are based on the Casio SK-1, gaining access to the innards of your keyboard will be relatively the same.
Detach the circuit board from the plastic mountings in order to gain access to the keyboard assembly and circuit board. This requires removing a few more small Phillips head screws. At this point, it's a great idea to take digital pictures of your keyboard's innards so you can to have a visual record of how the keyboard was assembled. Gently lay the circuit board aside.
Remove the main key assembly from the keyboard's body enclosure. Again, take pictures with a digital camera so you can see how things are assembled. Be very gentle when removing the keyboard assembly because it will probably be connected to various circuit boards by delicate wire.
Locate the "buttons" that are attached to the circuit board directly underneath the keyboard's keys. Look for are usually a strip of round buttons made out of gray or black rubber that are punched into the circuit board.
Remove the rubber strip of buttons from the circuit board. The rubber strip is not glued down but simply pressed into the circuit board via a few rubber nubs and holes in the circuit board. It will take minimal effort to remove the rubber strip of buttons from the circuit board, which should reveal a long strip of black contacts underneath.
Clean the contacts with a cotton swab and 90% isopropyl alcohol. Reassemble your keyboard. If necessary, use your pictures as a reference. Test it to make sure that your dead keys are now functioning.
Cleaning a "rail contact" keyboard Remove the bottom metal panel of the keyboard with your small Phillips head screwdriver. It is secured by a few small Phillips head screws. Although these directions are based on the Moog Satellite synthesizer, gaining access to the innards of your keyboard will be relatively the same.
Locate the "rail contacts" of your keyboard. The rail is a long, thin wire that stretches across most of the length of the keyboard directly underneath the keys. The rail is how the circuit is completed and the tone is accomplished by the small wires attached to each key that make contact with the rail when they are pressed.
Check the wires associated with each key; if any of them are bent upward, gently straighten them with a needle nose pliers. Clean the wires associated with each key and the length of the entire rail with a soft pencil eraser.
Reassemble your keyboard. If necessary, use your pictures as a reference. Test it to make sure that your dead keys are now functioning.