Operation Pcb - Kyocera Mita KM-1810 Service Manual

2-3-3 Operation PCB

key_sen[0]
key_sen[1]
The operation unit PCB (OPCB) consists of key switches and LEDs. The lighting of LEDs is determined by scan signals
(SCAN [0] to SCAN [7]) and LED lighting selection signals (LEDON [0] to LEDON [5]) from the main PCB (MPCB). The key
switches operated are identified by the scan signals (SCAN [0] to SCAN [7]) and the return signals (key sen [0], [1]).
As an example, to light "a1", the LED lighting selection signal (LEDON [0]) should be driven low in synchronization with a
low level on the scan signal (SCAN [7]). LEDs can be lit dynamically by repeating such operations.
As another example, if "K2" is pressed, the corresponding key switch is turned on feeding the low level of the scan signal
(SCAN [6]) back to the main PCB (MPCB) via the return signal (key sen [0]). 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.
CN2-2
CN2-1
_SCAN[0] CN1-3
_SCAN[1] CN1-2
_SCAN[2] CN1-1
_SCAN[3] CN2-7
_SCAN[4] CN2-6
_SCAN[5] CN2-5
_SCAN[6] CN2-4
_SCAN[7] CN2-3
a1
_LEDON[0] CN1-9
a2
_LEDON[1] CN1-8
a3
_LEDON[2] CN1-7
L1
_LEDON[3] CN1-6
L9
_LEDON[4] CN1-5
L17
_LEDON[5] CN1-4
Figure 2-3-5 Operation unit PCB block diagram
K2 K3 K4 K5 K6 K7
K14 K1 K9 K10 K11 K12
D2 D3 D4 D5 D6
b1 c1 d1 e1 f1 g1
b2 c2 d2 e2 f2 g2
b3 c3 d3 e3 f3 g3
L2 L3 L4 L5 L6 L7
L10 L11 L12 L13 L14-1 L15
L18 L19 L20 L21 L14-3
2A1/2
K8
K13
D7 D8
DP1
DP2
DP3
L8
L16
2-3-9