Keyboard Circuit - Olivetti ECR 7100 Service Manual

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4-9 KEYBOARD CIRCUIT

Keyboard scan is performed by CPU interrupt routine.
P10 through P17 are commonly used with scan signal. P43 through P47 are return line of Keyboard
Matrix.
It is consist of matrix of Strobe line(8)×Return line(5) and total of 37 keys are assigned.
In order to remove chattering, key entry is confirmed when two sequential entry of a key.
P50 is used for Mode lock switch, Feed key.
Circuit Diagram
CN2
SCAN0
15
SCAN1
14
SCAN2
13
SCAN3
12
SCAN4
11
SCAN5
10
SCAN6
9
SCAN7
8
RETURN0
7
RETURN1
6
RETURN2
5
RETURN3
4
RETURN4
3
RETURN5
2
MDRTN
1
2mm Pitch Board-in
SW1
RETURN0
SW10
RETURN1
SW18
RETURN2
SW26
RETURN3
SW33
RETURN4
RETURN5
52
D1 D2 D3
1N4148 1N4148 1N4148
SW2 SW3
00 10 20
SW11 SW12
01 11 21
SW19 SW20
02 12 22
SW27 SW28
03 13 23
04
ECR7100 Service Manual
D4 D5 D6
1N4148 1N4148 1N4148
SW4 SW5 SW6
30 40 50
SW13 SW14 SW15
31 41 51
SW21 SW22 SW23
32 42 52
SW29 SW30
33 53
SW34 SW35
44 54
Dial Switch Board
CN1 DC1
MDRTN
7 7
SCAN0
6 6
SCAN1
5 5
SCAN2
4 4
SCAN3
3 3
SCAN4
2 2
SCAN5
1 1
2mm Pitch Board-in 2mm Pitch Board-in
D7 D8 D9
1N4148 1N4148 1N4148
SW7 SW8 SW9
60 70 75
SW16 SW17
61 71
SW24 SW25
62 72
SW31 SW32
63 73
SW36 SW37
64 74
Y110910 - 8
COM
DS1
OFF
12 1
REG1
11 2
REG2
10
3
X
9 4
Z
8 5
PRG
7 6
Diode Direction
D1-D9 D1-D9
1N4148 1N4148
ECR6100 ECR6700