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KEYPAD TEST
This diagnostic is used to verify Keypad operation and
the Microboard’s ability to respond to a pressed key.
Refer to description of Keypad operation in Section
5 of this book.
Procedure
1. Press each keypad key. As the key is pressed, an
illuminated LED is displayed corresponding to
the key location on the keypad.
2. Press the DIAGNOSTICS key to return to the
MAIN DIAGNOSTICS Screen.
Troubleshooting
If an LED is not displayed when a key is pressed, the
Keypad, Keypad ribbon cable or Microboard could be
defective. Use the following procedure to locate the
defective component.
1. Keypad
a. Disconnect the ribbon cable from the Keypad.
b. Identify row/column coordinate of the key to
be tested. Refer to Figure 46.
c. In the Keypad connector, locate the pins of
the row/column coordinate of the key of the
key to be tested.
d. Insert the leads of an Ohmmeter into the pins
identied in step “c” above.
e. Press the key to be tested. If the contact
resistance is >100 Ohms, the Keypad is defec-
tive.
f. Release the key. If the contact resistance is < 1
Meg Ohm, the Keypad is defective.
2. Ribbon Cable
Using an Ohmmeter, perform a continuity test on
all conductors in the ribbon cable. An open circuit
would indicate the ribbon Cable is defective.
3. Microboard
There are no checks or measurements to be
made on the Microboard. If the Keypad and
Ribbon Cable check OK per the above procedures,
the Microboard is most likely the cause of the
problem.
FIG. 49
00568VIPC
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