Operation Unit Pcb - Kyocera KM-1650 Service Manual

2DA/2DB-1
2-3-5

Operation unit PCB

+5V
SGND
YC1
1
SGND
2
+5V
3
BUZERDRN
4
SCAN0
5
SCAN1
6
SCAN2
7
SCAN3
8
SCAN4
9
SCAN5
10
SCAN6
11
SCAN7
YC2
1
KEY0
2
KEY1
3
KEY2
4
KEY3
5
KEY4
6
KEY5
7
KEY6
8
KEY7
9
KEY8
10
KEY9
11
LED4
LED3
LED2
LED1
LED0
POWERKEY
K68
SGND
The operation unit PCB (OPPCB) consists of key switches, LEDs and buzzer. The lighting of LEDs is determined by scan
signals (SCAN0 to SCAN7) and LED lighting selection signals (LED0 to LED4) from the main PCB (MPCB). The key
switches operated are identified by the scan signals (SCAN0 to SCAN7) and the return signals (KEY0 to KEY9).
As an example, to light L1, the LED lighting selection signal (LED4) 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 (KEY9). 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.
2-3-18
BZ1
+5V
R1
L40
SGND
Figure 2-3-9 Operation unit PCB block diagram
K67 K63 K49 K39
K66 K62 K48 K38
K65 K51 K47 K37
K64 K59 K46 K36
K60 K58 K45 K35
K56 K57 K44 K33
K52 K55 K43 K32
K51 K54 K42 K31
K50 K53 K41 K30
D1 D2 D3
L35 L1 L25 L20
L41
L36 L31 L26 L21
L42
L37 L32 L27 L22
L43
L38 L33 L28 L23
L39 L34 L29 L24
K69
K29 K21 K17
K28 K20 K16 K40
K27 K19 K11 K34
K26 K18 K10 K5
K25 K15 K9 K4
K24 K14 K8 K3
K23 K13 K7 K2
K22 K12 K6 K1
D4 D5 D6 D7
L14 L10 L1
L15 L11 L6 L2
L16 L12 L7 L3
L17 L13 L6 L4
L18 L19 L9 L5
D8 D9