If the letters and numbers don't work, what is left ?
Keyboards are electronically organized into a matrix of rows
and columns. An internal processor monitors the columns
as it activates the rows one at a time in rapid succession,
or vice versa.
If a complete column or row is bad (electronically) then
a subset of keys will not work. For a PC, the detected key
strokes are encoded into special binary codes called
"scan-codes", which are sent to the PC over a serial cable
or a wireless link.
The operating system then employs several layers of
translation to determine which keys you pressed,
based on the language and location, as well as the actual
application actively running at the time. Also the keyboard
itself is programmable and re-configurable by software running
on the PC, such that the letter "A" for example, can generate
different scan-codes, depending on the selected keyboard
On laptops, multiple functions and the numeric number-pad
are overlaid over the main alphabetical section, such that a
single key can serve many functions, depending on the current
1) Make sure you don't have a software problem, and that your
keyboard is not stuck in some bizarre or foreign operating
2) Make sure that the wireless keyboard's batteries are not weak
3) Make sure that there is a clear communication path between
the physical keyboard and the USB transceiver plugged into
the computer. CRT monitors and large metal objects will
interfere with this signal.
4) Reset the keyboard: Unplug the USB cable, and plug it
back in, or re-boot the PC.
5) If these easy checks don't fix it, contact the manufacturer,
or replace the keyboard, as these things are generally not
Typically the processor/controller is a single proprietary chip,
the circuit board has multiple layers which are very hard to
trace or repair, schematics are non-existent, and the switch
mechanics are very finicky and delicate. The actual
key-switches can use dozens of different principles, including:
capacitance, inductance, carbon pressure pads, conductive
foam, printed pressure bubbles, reed switches, optics....
you name it.
There is no practical way to repair these things, and at an
average price of $25-$100 for a new keyboard, it
is hardly worth it.
May 08, 2008 |
Fellowes Cordless Optical Keyboard/Mouse...