Casio DR-120XA Troubleshooting guide

R
(without price)
DR-120XA (LX-224C/D)
DL-220BAGY(LX-224I)
DR-320A (LX-224B)
SEP. 1995
DR-120XA
INDEX

CONTENTS
1. SPECIFICATIONS ......................................................................................................... 1
2. BLOCK DIAGRAM ........................................................................................................ 1
3. CPU (MN15418YCY) PIN FUNCTION........................................................................... 2
4. DIAGNOSTIC................................................................................................................. 3
5. TROUBLESHOOTING................................................................................................... 4
6. DISASSEMBLY VIEW ................................................................................................... 5
7. SCHEMATIC DIAGRAM................................................................................................ 6
8. PARTS LIST ................................................................................................................ 10

— 1 —
Display tube
FG138AW7
CPU
MN158418YCY
Power supply
circuit
Slide switch
Keyboard
Printer
M-80
VF1,VF2
Ribbon shift signal
Character selective signal
Timing pulse
Digital signal
D1~D13
Motor control signal
VDD, VSS
Sent signal
S1~S7, SAP, SDP
SO1~SO7
SI1~SI3, SI5
KO1 ~ KO8
KI1 ~ KI6
VIM, VDD
1. SPECIFICATIONS
Roll paper size : Width: 57 ~ 58 mm
Ink ribbon : Red/Black: RB-02
Green/Black: GB-02
Power source : AC 100, 120, 220 or 240 (±10 V), 50/60 Hz
• Refer to the operation manual for other specifications.
2. BLOCK DIAGRAM

— 2 —
Pin No. Signal I/O Function
1~7, 64 P00~P13 Out Common signal for keyboard
8~12 P20~P22, P32, P33 In Key signal from keyboard
13 IRQ In Timing pulse signal from printer
14 DEBIN In Reset pulse (Not used)
15 IRQCNT In Auxiliary timing (VDD)
16 P40 Out Motor control signal
17 P41 Out Ribbon shift signal for printer
18~30 P42, P43, P50~P53, Out Character selective signal for printer
P70~P73, P80~P82
31, 32 P83, P90 Out Segment signal for display,
Character selective signal for printer
33~39 P91~P93 Out Common signal for slide switch,
PA0~PA3 Segment signal for display
40 P60 In Input port (VDD)
41~43 P61~P63 In Signal from slide switch
44~56 PB0~PB3, Out Digit signal for display
PC0~PC3,
PD0~PD3,
PE0
57 VPP In GND terminal
58 VDD In VDD terminal (+33V)
59, 60 OSC1, OSC2 I/O Clock signal for CPU
61 VSS In VSS terminal (+28V)
62 SYNC — Not used
63 RST In Signal from slide switch, Reset signal
3. CPU (MN158418YCY) PIN FUNCTION

— 3 —
OPERATION
1 00 TM
C
8 – ÷9 % ◊/#
CA
• 1 2 3 4 5 6 7
M+
M+
M–
÷5 MU/MD
+
=
+
=
M◊
M❊
CA 1 ÷ ÷ 1 M
X 1 – 1 –
◊/#
◊/#
–
IT
❊
G❊
FEED
M❊AC
1 • =
0 • 01M+
0 • 01 X
[- 1 • =]
[- 0 • 01 +]
[0 • 01-]
[0 • 01-]
[- 0 • 02 ◊]
002
[- 0 • 02◊]
[-0 • 01-]
001
001
[- 0 • 03 G❊]
001
[- 0 • 03 G❊]
Paper feeding
001 0 • 01M❊
• • 0 • •
NOTE
The character with
"[ ]" will be printed
by red ink.
Press the button 2
or 3 seconds
continuously.
STEP
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
4. DIAGNOSTICS
MODE SWITCHES
ON F 6
ON F 6
ON F 6
ON F 6
ON CUT 6
ON CUT 6
ON CUT 6
ON CUT 4
ON UP 3
ON 5/4 2
ON 5/4 1
ON 5/4 0
ON 5/4 ADDX
ON 5/4 ADDX
PRINT 5/4 ADDX
PRINT 5/4 ADD+
PRINT 5/4 ADD+
ITEM+ 5/4 ADD+
ITEM+/– 5/4 ADD+
ITEM+/– 5/4 ADD+
ITEM+/– 5/4 ADD+
ITEM+/– 5/4 ADD+
ITEM+/– 5/4 ADD+
ITEM+/– 5/4 ADD+
▲
DISPLAY
100°0.
-88.8888888888
-88.888888888
0.
0.1234567
M 0.123456
M 0.1234
M 0.124
M 0.12
M 0.1
M 0.
M 0.123
0.123
M 0.01'
K
M -0.02
M -0.02
M -0.02
M -0.03
M 001
M -0.03
M -0.03
0.
PRINT
[-]
[88.8888888888]
• • 0 • •
1 • ÷
1 • K÷
0 • 01 ÷

— 4 —
1) Does not work
at all.
2) No display.
3) No print.
4) Poor display.
5) Poor printing
• Motor does
not stop.
• Missing of
digits. •Refer to the printer service manual published separately.
VDD, VSS, VM, VF1, and
VF2 are OK?
Check the pulse signals
from LSI.
If VF1, VF2, Digit and
Segment signals are OK.
VM=17V (while printing)
Check detector of printer
block and timing signal.
Secondary voltage
of transformer
Waveforms of each
pin
VF1, VF2
Signal D1 ~
S1 ~
Between LSI and
display tube
Trouble Cause Checkpoint Note
5. TROUBLESHOOTING
•Defective power transformer
•Defective LSI
•No voltage at VF1, VF2
•No digit signal or no segment
signal
•Defective display tube
•Poor voltage VM
•Defective motor
•Defective LSI
•Short or open circuits between
digit signals and segment sig-
nals.
•Defective display tube
•Timing signal is bad.
•Defective printer magnet

— 5 —
6. DISASSEMBLY VIEW
14
1
2
3
4
5
6
8
7
9
10
11
12
13
15
16
17
18
19
20
21
23
22
24
25
26
19
Power Cord
Projection side
Black
Projection side
Marking side
Brown
Blue
Brown
Blue
Transformer
Yellow
Black
Blue
Black
Black
White
Black
Red
Connection
Voltage
100V
120V
220V
240V

— 6 —
7. SCHEMATIC DIAGRAM
7-1. Main board

— 7 —
7-2. Keyboard
KO1
KO2
KO3
KO4
KO5
KO6
KO7
KO8
FEED
X
6
5
4
CA
M
/
–
9
8
7
M
G*
.
0
C
MU/MD
M+
/ #
+
3
2
1
%
M–
IT
TIME
00
000
KI1 KI2 KI3 KI4 KI5 KI6

— 8 —
7-3. Slide Switch Board
OFF
ON
PON
IT+
IT–
F
CUT
UP
5/4
6
4
3
2
1
0
ADDX
ADD+
SO1
SO2
SO3
SO4
SO5
SO6
SO7
VSS SI5
SI3
SI2
SI1
MODE SWITCH