Troubleshooting the keypad in the display unit
When a key is pressed on the keypad of the programme unit, two of the
outputs on the keypad close. By disconnected the flat cable from the
display card, pressing a key and the measuring the resistance between the
outputs that should close, it is possible to determine correct operation of
any one key.
The table below shows the outputs that need to be closed for each
39
key:
Key
Outputs that should close
1
2
4
5
6
7
8
9
0
A
B
C
D
39
Troubleshooting
2 + 7
2 + 6
2 + 5
+ 7
+ 6
+ 5
4 + 7
4 + 6
4 + 5
5 + 8
6 + 8
1 + 2
1 +
7 + 8
B
C
A
D
6
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