Operation Unit Pcb - Kyocera KM-1620 Service Manual

2C9

2-3-4 Operation unit PCB

+5V
BZ1
YC1
10
+5V
9
BUZERDRN
8
SCAN7N
7
SCAN6N
6
SCAN5N
5
SCAN4N
4
SCAN3N
3
SCAN2N
2
SCAN1N
1
SCAN0N
YC2
1
KEY4
2
KEY3
3
KEY2
4
KEY1
5
KEY0
6
LED12
7
LED11
8
LED10
9
LED9
10
LED8
11
LED7
12
LED6
13
LED5
14
LED4
15
LED3
16
LED2
17
LED1
18
LED0
The operation unit PCB (OPPCB) consists of key switches, LEDs, 7 segment LED and buzer. The lighting of LEDs is
determined by scan signals (SCAN0 to SCAN7) and LED lighting selection signals (LED0 to LED12) from the main PCB
(MPCB). The key switches operated are identified by the scan signals (SCAN0 to SCAN7) and the return signals (KEY0 to
KEY4).
As an example, to light L1, the LED lighting selection signal (LED0) should be driven low in synchronization with a low level
on the scan signal (SCAN0). LEDs can be lit dynamically by repeating such operations.
As another example, if K1 is pressed, the corresponding key switch is turned on feeding the low level of the scan signal
(SCAN0) back to the main PCB (MPCB) via the return signal (KEY0). The main PCB (MPCB) locates the position where the
line outputting the scan signal and the line inputting the return signal cross, and thereby determines which key switch was
operated.
2-3-14
K5 K10 K15 K20
K4 K9 K14 K19
K3 K8 K13 K18
K2 K7 K12 K17
K1 K6 K11 K16
D1 D2 D3
L37
L9 L18 L27 L36
L8 L17 L26 L35
L7 L16 L25 L34
L6 L15 L24 L33
L5 L14 L23 L32
L13 L22 L31
L3 L12 L21 L30
L2 L11 L20 L29
L1 L10 L19 L28
Figure 2-3-7 Operation unit PCB block diagram
K25 K30 K38
K24 K29 K34 K37
K23 K28 K33 K36
K22 K27 K32
K21 K26 K31 K35
D4 D5 D6 D7
L75 L74
L46 L55 L64 L73
L45 L54 L63 L72
L44 L53 L62 L71
L43 L52 L61 L70
L42 L51 L60 L69
L41 L50 L59 L68
L40 L49 L58 L67
L39 L48 L66
L38 L47 L56 L65
SW
U1
10
e3
6
e2
1
e1
D8
11
d3
7
d2
2
d1
13
c3
8
c2
4
c1
15
b3
20
b2
24
b1
16
a3
21
a2
25
a1
7 segment
LED
27
f1
23
f2
17
f3
28
g1
22
g2
12
g3
5
DP1
9
DP2
14
DP3
3
Dig1
26
Dig1
19
Dig2
18
Dig3