A SERVICE OF

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59
PRELIMINARY
(a) MCU detects the status of EPO button (on LCD display panel) via “EPO” (85) (low active). When the EPO button is activated, UPS will shut
down the output and turn off the inverter. When the EPO button is released, UPS will stay in bypass mode.
(b) MCU can control the LCD backlight via “U-lcmBL” (62).
(c) MCU can adjust the contrast of LCD by PWM control via “U-lcmCA” (2).
2 Theory of Operation (continued)
2.11 LCD Panel Control Circuit
Located at NH-SYS-M board (System MCU and Control Circuit)
VLED
CM120
G1
+12VS
CM1 2 1
COM
9
1B
1
1C
16
2B
2
2C
15
3B
3
3C
14
4B
4
4C
13
5B
5
5C
12
6B
6
6C
11
7B
7
7C
10
GND
8
UM5
G1
LED1
LED0
LED3
LED2
LED5
LED4
CM8 5
RM126
ESC
RM127
KEY_ESC
G1
KEY_ESC
CM103
RM147
UP
RM149
KEY_UP
G1
KEY_UP
CM9 1
RM133
DOWN
RM135
KEY_DOWN
G1
KEY_DOWN
CM110
RM152
ENT
RM154
KEY_ENT
G1
KEY_ENT
CM9 6
RM140
OFF
RM143
KEY_OFF
G1
KEY_OFF
G1
CM7 5CM7 4CM7 3CM7 2 CM7 9CM7 8CM7 7CM7 6
TO LCD
BYP_ O K
(70)
(39)
(37)
(35)
(33)
(73)
(74)
(75)
(76)
(77)
(78)
(10)
(9)
(22)
(7)
(8)
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 26
27 28
29 30
CNM5
G1
VLED
G1
VLED
LED0 LED1
LED2 LED3
LED4 LED5
OFF ENT
ESC UP
DOWN BKL IT
CONTRAST Lc dDATA
LcdWR Lc dCS
NO+ G1
LED0
LED1
LED2
LED3
LED4
LED5
NORMAL LED
BYPASS LED
FAULT LED
BATTERY LED
NC
NC
Stand-A lone
RM134
RM1 3 8
+12VS
G1
RM137
QM9
RM1 3 9
G1
BKL IT
(62)
RM1 4 8
NO+
CM104
G1
(85)
RM144
5VS
RM1 5 5
G1
CM112
CM1 1 3
G1
+12VS G1
CON T RAST
(2)
CM6 7
RM1 1 6
ZD M1
CM8 0
RM1 2 1
ZD M2
G1
CM9 0
RM132
ZD M3
G1
LcdDATA
LcdCS
LcdWR
(50)
(49)
(63)
(38)
(36)
(34)
(32)
Vin
1
GND
2
+5V
3
UM10
RM158
CM1 1 8 CM119
U- LED0
U- LED1
U- LED2
U- LED3
U- LED4
U- LED5
CE NT RAL _ OK
U- LcmBL
EPO
U- LcmCA
U- LcdDATA
U- LcdCS
U- LcdWR
LcdD1
LcdD3
LcdD5
LcdD7
LcdD0
LcdD2
LcdD4
LcdD6
G1
4 11
1
3
2
1
UM7A
LM324AD
1
HSM1
HS