Thread: Breakdown to Breakthrough

Although their appearance may seem daunting at first glance, keyboard systems are not terribly difficult to troubleshoot, primarily because of their modularity if all else fails, replacing a keyboard is a simple matter. The keyboard's great weakness, however, is its vulnerability to the elements. Spills, dust, and any other foreign matter that finds its way between the key caps can easily ruin a keyboard. The keyboard's PC board is also a likely part to be damaged by impacts or other physical abuse. The following symptoms address many of the most troublesome keyboard problems.

Symptom 1 :

The keyboard is completely dead, i.e. no keys appear to function atall. This symptom assumes that your computer initializes and boots to its DOS prompt or other operating system as expected, but the keyboard does not respond when touched. Keyboard status LEDs (lights above the num-pad) mayor may not be working properly. Your first step in such a situation is to try a properly working keyboard in the system. Note that you should reboot the system when a keyboard is replaced. If a known-good keyboard works, the fault is probably on the keyboard interface chip. You can attempt to replace this chip if you wish, but it is often most economical to simply replace the keyboard rather than the chip.



If another keyboard fails to correct the problem, use a multimeter and check if it supplies +SV at the keyboard connector. If the +SV signal is missing, the female keyboard connector may be broken. Check the connector's soldering junctions on the motherboard. Reheat any connectors that appear broken. Many motherboards also use a "pico-fuse" to protect the + SV supply feeding the keyboard connector. If your + SV is lost, locate and check the keyboard connector fuse. If problems continue, replace the motherboard.