York MILLENNIUM YCUL0016SC, Assembly, Installation, Operation & Maintenance

Page: 139 / 172

YORK INTERNATIONAL
FORM 150.63-NM1
139
KEYPAD
The operator keypad is connected to the microboard by
a ribbon cable, which is connected to J2 on the
microboard.
The integrity of a specific “button” on the keypad can
be verified by doing a continuity check across two spe-
cific points (or pins), that represent one of twelve “but-
tons” on the keypad.
Table 34 lists the key/pin assignments for the keypad.
Power to the microboard must be turned off, and
the ribbon cable disconnected from the microboard
prior to conducting the tests, or component damage
may result.
After the ribbon cable is disconnected from microboard,
ohmmeter leads are connected to the pins representing
the specific “button” to be tested. After connecting the
meter leads, the “button” being checked is pressed and
a reading of zero ohms should be observed. After re-
leasing the “button”, the resistance value should be
infinite (open circuit).
Pin 1 is usually identified by a stripe
on the ribbon cable.
FIG. 14 – MICROBOARD RELAY CONTACT
ARCHITECTURE
LD03842
TABLE 34 – KEYPAD PIN ASSIGNMENT MATRIX
KEYPAD PIN CONNECTIONS
STATUS 1 TO 5
OPER DATA 1 TO 7
PRINT 1 TO 6
HISTORY 1 TO 8
UP ARROW 2 TO 5
DOWN ARROW 2 TO 7
ENTER/ADV 2 TO 6
COOLING SETPOINTS 2 TO 8
SCHEDULE/ADVANCE DAY 3 TO 5
PROGRAM 3 TO 7
OPTIONS 3 TO 6
CLOCK 3 TO 8
4