YORK INTERNATIONAL
154
FORM 160.54-M1(503)
KEYPAD TEST
FIG. 66 – KEYPAD TEST SCREEN
00336VIP
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 8
of this book.
PROCEDURE
1. Press each keypad key. As the key is pressed, an
il lu mi nat ed 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 Key pad.
b. Identify row/column coordinate of the key to be
test ed. Refer to Figure 33.
c. In the Keypad connector, locate the pins of the
row/column coordinate of the key of the key to be
test ed.
d. Insert the leads of an Ohmmeter into the pins
iden ti fi ed in step “c” above.
e. Press the key to be tested. If the contact re sis tance
is >100 Ohms, the Keypad is defective.
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 Ca ble is defective.
3. Microboard
There are no checks or measurements to be made
on the Microboard. If the Keypad and Ribbon Ca ble
check OK per the above pro ce dures, the Microboard
is most likely the cause of the prob lem.
Diagnostics & Trou ble shoot ing
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