LD03842
FIG. 9 – MICROBOARD RELAY CONTACT ARCHITECTURE
KEYPAD
The operator keypad is connected to the microboard by a ribbon cable, which is connected to J2 on the mi- croboard.
The integrity of a specific “button” on the keypad can be verified by doing a continuity check across two specific
FORM
points. (or pins), that represent one of twelve “buttons” on the keypad.
Table 49 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 dam- age may result.
After the ribbon cable is disconnected from microboard, ohmmeter leads are connected to the pins represent- ing 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 releasing the “button”, the resistance value should be infinite (open circuit).
Pin 1 is usually identified by a stripe on the ribbon cable
3
TABLE 49 – KEYPAD PIN ASSIGNMENT MATRIX
KEYPAD | PIN CONNECTIONS |
STATUS | 1 TO 5 |
OPER DATA | 1 TO 7 |
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 |
YORK INTERNATIONAL | 103 |
