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Figure 2 - 1 .
Keypad
2 . 4
KEYBOARD PROBLEMS
Keyboard problems may result from mal functions in the keyboard, its
interconnecting cab l e , or the p l anar board .
"sticky" or that produce wrong characters indicate that you need to re
p l ace the keyboard and its interconnecting cab l e . When the D and G keys
both produce the letter D , the p lanar board is faulty and needs replacing.
A tota l ly "dead" keyboard could be the result of either a faulty keyboard
or planar board.
To test if each key on the keyboard is operating properly, a keyboard
"echo" test is provided in the system as test lA. Y ou may cal l for test
lA on the keyboard or on the keypad assemb ly . See Section 3 . 6 . 1 , "Keyboard
Echo Test - - Test lA . "
keyboard as it is press ed and released should produce the same codes on
the CRT as are found in Figure 3 - 3 .
tinguish between a "dead" keyboard and a mal functioning p l anar board . See
Sect ion 3 . 6 . 2 , "Volt age Check . "
Test LED
'Test Number' LED
After the echo test is cal l ed , each key on the
An optional vo ltage check can dis
Keys that are "dead" or
Fault Detection 2 - 10
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