NEC NEC MultiSync LCD1550X LCD1550X LCD1550X, Service Manual

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1.7.1 Switch board interface
52852-1290
52807-1210
Layout looking from back of panel
POWER
LED
RESET NEXT
ADJUST
CONTROL
EXIT
+
-
RIGHT
LEFT
1
3 4 5 6 7 8 9 10 11 12
2
J100
1 3 4 5 6 7 8 9 10 11 12 2
LED P G
LED P U
LEFT
EXIT
-
RIGHT
+
NEXT
POWER SW
GND
RESET
GND
SW board
J800
M3_3V
M3_3V
IC102
microcomputer
LED_P_G
LED_P_U
M3_3V
35
36
68
69
70
71
72
73
74
76
MAIN board
220
Ω
220
Ω
4.7k
Ω
4.7k
Ω
4.7k
Ω
4.7k
Ω
10k
Ω
x 8
Calculation of LED (CP264P480A10) drive current
Maximum rating : P
D
= 75mW, I
F
=30mA Photoelectric characteristics: V
F
= 1.9V
LED drive current = (M3_3V-V
F
) / 220
Ω
(transistor's V
CE(sat)
is ignored)
= 6mA < 30mA
LED power = (M3_3V-V
F
) x 6mA
= 8.4mW < 75mW
µ
-COM Pin No.
68
69
70
71
72
73
74
76
35
36
I/O
I
I
I
I
I
I
I
I
O
O
Signal name Remarks Function
LEFT
EXIT
-
RIGHT
NEXT
+
SW_DET
RESET
LED_P_G
LED_P_U
PWB-SW OSM menu selection : Normally 1, Lo when switch is pressed
OSM menu selection : Normally 1, Lo when switch is pressed
OSM menu selection : Normally 1, Lo when switch is pressed
OSM menu selection : Normally 1, Lo when switch is pressed
OSM menu selection : Normally 1, Lo when switch is pressed
OSM menu selection : Normally 1, Lo when switch is pressed
Front power switch monitoring : Normally 1, Lo when switch is pressed
OSM menu selection : Normally 1, Lo when switch is pressed
Hi (default value) : Off, Lo : green LED On
Hi (default value) : Off, Lo : orange LED On
List of control signals