Display Circuit - Olivetti ECR 7900 Service Manual

3-7. DISPLAY CIRCUIT

VCC3
C2 0
0.1 uF
U1 1
D0 R6 6
2 18
A1 B1
D1 R6 7
3 17
A2 B2
D2 R6 8
4 16
A3 B3
D3 R6 9
5 15
1
A4 B4
D4 R7 0
6 14
A5 0 B5
D5 R7 1
7 13
A6 B6
D6 R7 2
8 12
A7 B7
D7 R7 3
9 11
A8 B8
RD#
1
DIR
19
G
SN74LV 245AP WR
VCC3
C2 3
0.1 uF
U1 2
A0 R7 4
2 18
A1 Y1
RD# R7 5
3 17
A2 Y2
LCD_RS T# R7 6
4 16
A3 Y3
WR# R7 7
5 15
A4 Y4
LCD_CS # R7 8
6 14
A5 Y5
7 13
A6 Y6
8 12
A7 Y7
C5 5
9 11
A8 Y8
*10 00pF
1
G1
19
G2
SN74LV 541AP WR
VCC5
Q7
E C
2SA 1036 K
R9 8
10K
R1 68
2K
Q6
DTC143 EKA
B
BKL_ON
Trouble shooting
- No display but backlight turns on - - Replace LCD unit or Main board.
- Display OK, but backlight does not turn on.
Check voltage at point (2)
DC +5V - - - Replace LCD unit.
DC 0V - - - Replace Main board.
- No display and no backlight.
Check voltage at point (1)
DC +5V - - - Replace LCD unit or Main board.
DC 0V - - - Check Power supply circuit. (P.9-11)
30
33
33
33
33
33
33
33
33
33
33
33
33
33
(2)
ECR 7900 Service Manual
ZD1 ZD2 ZD3 ZD4 ZD5 ZD6
VCC5
FB 7
0(3 216)
C114
EC10
+
C2 2
(1)
100 uF_1 6V
0.1 uF
FB 6
0(3 216)
CN11
C21
1
2
0.1uF
3
4
LC_CD#
5
LC_RD#
6
LC_RST#
7
LC_WR#
8
LC_D0
9
LC_D1
10
LC_D2
11
LC_D3
12
LC_D4
13
LC_D5
14
LC_D6
15
LC_D7
16
LC_CE#
17
LC_LEDA R3 6
18
0
19
20
C24 C0 3-20A G1 1 0 x 2 (MAL E)
0.1uF
10x2 Box-Header(P=2.54mm)
Y108540-8