Symptom 2:

One or more key appear to work erratically, or are inoperative. The computer operates normally and most keys work just fine, but one or more keys do not respond when pressed. Extra force or repeated strikes may be needed to operate the key(s). This type of problem can usually range from a minor nuisance to a major headache. Chances are that your key contacts are dirty. Sooner or later, dust and debris works into all key switches. Electrical contacts eventually become coated and fail to make contact reliably. This symptom is typical of older keyboards, or keyboards that have been in service for prolonged periods of time. In many cases, you need only vacuum the keyboard and clean the suspect contacts with a good-quality electronics-grade contact cleaner.

Now to overcome the problem, begin by disconnecting the keyboard. Use a static-safe, fine¬tipped vacuum to remove any accumulations of dust or debris that may have accumulated on the keyboard's PC board. You may wish your keyboard vacuum cleaned regularly as preventive maintenance. Once the keyboard is cleaned, gently remove the plastic key cap from the offending key(s). You can expect the cap to slide off with little resistance. Do not rip the key cap off or else you stand a good chance of damaging the cap and causing permanent damage to key switch.



Use. a can of good-quality electronics-grade contact cleaner and, spray a little bit of cleaner into the switch assembly. When spraying, attach the long narrow tube to the spray nozzle-this directs cleaner into the switch. Work the switch in and out to distribute the cleaner. Repeat once or twice to clean the switch thoroughly. Allow residual cleaner to dry thoroughly before retesting the keyboard. Never use harsh cleaners or solvents. Industrial-strength chemicals can ruin plastic components. Re-apply power and retest the system. If the suspect key( s) responds normally, install the removed key cap and return the system to service. As a preventive measure, you might wish to go through the process of cleaning every key.

Membrane keys must be cleaned somewhat differently from mechanical keys. You need to remove the rubber or plastic boot to clean the PC board contacts. Depending on the design of your particular membrane switch, this may not be an easy task. If you are able to see the contact boot, use a pick or tweezers to gently lift the boot. Spray a bit of cleaner under the boot, and then work the key to distribute the cleaner. If the boot is confined within the individual key, you may have to remove the suspect key before applying cleaner.
If cleaning does not work, your next step should be to disassemble the keyboard and replace the defective key switches. Observe the board closely for cracks or fractures. Extra care helps prevent accidental damage to the PC keyboard. You also have the more economical option of replacing the entire keyboard assembly.