Casio CTK-431 User manual

ELECTRONIC KEYBOARD
CTK-431
CTK-431
MIDI
100 SONG BANK KEYBOARD
MUSICAL INFORMATION SYSTEM
SONG BANK CONTROLLER
POWER/MODE
ON
OFF
FINGERED
MAIN
VOLUME SYNCHRO/ FILL-IN START/ STOP TEMPO CHORD BOOK
ACCOMP VOLUME
CASIO CHORD
NORMAL
M
01234
56789
m 7 M7 dim
TONE
RHYTHM
SONG BANK
STATUS
MAIN VOLUME
TEMPO
aug sus4 -5 add9 CLEAR
RHYTHM
TRANSPOSE/
TUNE/MIDI
LEFT
ON/OFF RIGHT ON/OFF
REW STOP FF
TONE SONG BANK
P
L
A
Y
/
P
A
U
S
E
SONG BANK CONTROLLER
MUSICAL INFORMATION SYSTEM
OUTIN
OUTPUT
PHONES/ DC 9V

CONTENTS
Specifications ................................................................................................................................... 1
Block Diagram.................................................................................................................................. 2
Circuit Description ............................................................................................................................ 3
Adjustment ....................................................................................................................................... 7
Major Waveforms ............................................................................................................................. 8
Printed Circuit Boards ...................................................................................................................... 9
Schematic Diagrams ...................................................................................................................... 10
Exploded View ............................................................................................................................... 14
Parts List ........................................................................................................................................ 15

— 1 —
SPECIFICATIONS
GENERAL
Keyboard: 49 standard-size keys, 4 octaves
Tones: 100
Polyphony: 12 notes maximum (6 for certain tones)
Auto accompaniment
Rhythm patterns: 100
Tempo: Variable (236 steps, = 20 to 255)
Chords: 2 fingering methods (CASIO CHORD, FINGERED)
Rhythm controller: START/STOP, SYNCHRO/FILL-IN
Accomp volume: 0 to 9 (10 steps)
Song bank
Tunes: 100
Controllers: PLAY/PAUSE, STOP, REW, FF, LEFT ON/OFF, RIGHT ON/OFF
Musical dictionary
Name display: TONE, RHYTHM, SONG BANK name/number, keyboard settings name/value
Tempo: Tempo value, metronome, synchro standby, beat indicator
Chord: Chord name, Chord form
Fingering: Fingering indicators, parts, pedal (The pedal indicator is for received MIDI
data only.)
Song bank status: PLAY, PAUSE, REW, FF
Staff: 4 octaves with sharp and flat indications
Keyboard: 4 octaves
MIDI: 5 multi-timbre receive
Other functions
Transpose: 12 steps (–6 semitones to +5 semitones)
Tuning: Variable (A4 = approximately 440 Hz ±50 cents)
Volume: 0 to 9 (10 steps)
Terminals
MIDI terminals: IN, OUT
Phones/Output terminal: Stereo standard jack (Output is monaural.)
Output Impedance: 60 Ω
Output Voltage: 5 V (RMS) MAX
Power supply terminal: 9 V DC
Power supply Dual power supply system
Batteries: 6 AA-size batteries
Battery life: Approximately 2 hours (SUM-3/R6P)/4 hours (AM3/LR6)
AC adaptor: AD-5
Auto power off: Turns power off approximately six minutes after last key operation. Can be
disabled manually.
Speaker output: 3.0 W (Output is monaural.)
Power consumption: 9 V --- 7.5 W
Dimensions (HWD): 958 ×310 ×132 mm (37-3/4 ×12-3/16 ×5-3/16 inches)
Weight: Approximately 3.5 kg (7.7 lbs) (without batteries)
ELECTRICAL
Current drain with 9 V DC:
No sound output 200 mA ±20 %
Maximum volume 750 mA ±20 %
with 12 keys C1 to B1 pressed in Synth-Lead 1
Volume: 9 (Max.)
Phone output level (Vrms with 8 Ωload each channel):
with key A4 pressed in Synth-Lead 1 95 mV ±20 %
Speaker output level (Vrms with 4 Ωload each channel):
with key C4 pressed in Synth-Lead 1 1050 mV ±20 %
Output level (Vrms with 47 KΩload each channel):
with key C1 pressed in Synth-Lead 1 1100 mV ±20 %
Minimum operating voltage: 5.7 V

— 2 —
BLOCK DIAGRAM
CPU
MSM 6755C-17
LSI1
Keyboard
Buttons
LCD LCD Driver KS0066U-10B
LSI3
Reset IC
IC1 Oscillator X1, Q1
Power Supply Circuit
Q101 ~ Q103, D104
Power Amp.
LA4598
IC101 Filter
Q105
Speaker
(L)
Speaker
(R)
Phones/Output
VC AVDDVCC DVDD
APO
MD0 ~ MD7
MA0 ~ MA17
DC + 9 V IN
DB4 ~ DB7
COM1 ~ COM16
SEG1 ~ SEG40
RS
R/W
EKO8 ~
KO12 KI0 ~ KI6
KO0 ~ KO7
ROM(2M-bit)
UM23C2101M
7384/Q
LSI2
Power Switch

— 3 —
KI0 KI1 KI2 KI3 KI4 KI5 KI6
KO0 C2 G#2 E3 C4 G#4 E5 C6
KO1 C#2 A2 F3 C#4 A4 F5
KO2 D2 A#2 F#3 D4 A#4 F#5
KO3 D#2 B2 G3 D#4 B4 G5
KO4 E2 C3 G#3 E4 C5 G#5
KO5 F2 C#3 A3 F4 C#5 A5
KO6 F#2 D3 A#3 F#4 D5 A#5
KO7 G2 D#3 B3 G4 D#5 B5
KO8 —+0
Tempo Tempo Volume Volume
Down Up Down Up
KO9 321
Start/ Synchro/ Chord Accomp
Stop Fill-in Book Volume
KO10 654
Transpose/ Song Rhythm Tone
Tune Bank
KO11 98
7
Fingered CASIO Normal Power Off
Chord
KO12 FF Right Play/ Stop Left Rewind
Pause
CIRCUIT DESCRIPTION
KEY MATRIX
NOMENCLATURE OF KEYS
C2
C#2 D#2 F#2 G#2 A#2 C#3 D#3 F#3 G#3 A#3 C#4 D#4 F#4 G#4 A#4 C#5 D#5 F#5 G#5 A#5
D2 E2 F2 G2 A2 B2 C3 D3 E3 F3 G3 A3 B3 C4 D4 E4 F4 G4 A4 B4 C5 D5 E5 F5 G5 A5 B5 C6

— 4 —
CPU (LSI1: MSM6755C-17)
The CPU reads sound data from the ROM in accordance with the pressed key and the selected tone; the CPU
can read rhythm data simultaneously when a rhythm pattern is selected. Then it provides the left and the right
channels’ waveforms separately, by converting the data into the waveforms with two built-in DACs. The CPU
also controls key and button input. The following table shows the pin functions of LSI1.
Pin No. Terminal In/Out Function
1 MA14 Out Address bus
2, 3 NCO — Not used
4 ~ 19 MA0 ~ MA13 Out Address bus
13 MRDB Out Read enable signal
17 MCSB — Not used
20 ~ 27 MD0 ~ MD7 In/Out Data bus
28, 29 NC1, NC2 — Not used
30 DGND In Ground (0 V) source
31 DVCC In +5 V source
32, 33 XTLO, XTLI In/Out 20 MHz clock input/output
34 NC3 — Not used
35 RSTB In Reset signal input
36 P24/RXD — MIDI signal input
37 P25/TXD — MIDI signal output
38 NMI In Power ON signal input. Connected to +5 V.
39 APO Out APO (Auto Power Off) signal output
40 NC4 — Not used
41 REFH Out Terminal for the internal DAC
42, 43 NC5, NC6 — Not used
44 DAOR Out Sound waveform signal output
45 NC7 — Not used
46 AVdac In +5 V source for the internal DAC
47 DAOL Out Left channel sound waveform output
48 REFL Out Terminal for the internal DAC and ADC
49 AGdac In Ground source for internal DAC
50 AGadc In Ground source for internal ADC
51 ANI In Not used
52 AVadc In +5 V source for the internal ADC
53 NC8 — Not used
54 MOD0 In Mode selection terminal. Connected to +5 V.
55, 56 MOD1, MOD2 In Mode selection terminal. Connected to ground.
57 P40 — Not used
58 ~ 64 KI0/P30 ~ KI7/P36 In Terminals for key/button input signal
65 KI7/P37 — Not used
66 ~ 73 KO0/P50 ~ KO7/P57 Out Terminals for key scan signal

— 5 —
Pin No. Terminal In/Out Function
74 ~ 77 DB4 ~ DB7 Out Data bus for the LCD driver
78 NC9 — Not used
79 LVCC In +5 V source
80 ~ 84 KO8 ~ KO12 Out Terminals for button scan signal
85 ~ 87 P65 ~ P67 — Not used
88 RS Out Control signal for the LCD driver
89 R/W Out Read/Write signal for the LCD driver
90 E Out Chip enable signal for the LCD driver
91 ~ 95 P73 ~ P77 — Not used
96 LGND In Ground source
97, 100 MA18, MA15 Out Address bus
LCD DRIVER (LSI3: KS0066U-10B)
The LCD driver can drive a dot matrix LCD having 40 segment and 16 common lines. The LSI contains 240
graphic symbols in the built-in character generator ROM, and stores 80 characters in the built-in display data
RAM. In accordance with command from the CPU, the LSI is capable of displaying up to 16 characters
simultaneously. The following table shows the pin functions of LSI3.
Pin No. Terminal In/Out Function
1 ~ 22, SEG1 ~ SEG40 Out Segment signal output
63 ~ 80
23 VSS — GND (0 V) source
Terminals for the built-in clock pulse generator. The
24, 25 OSC1, OSC2 In/Out external resistor connected determines the oscillation
frequency.
LCD drive voltage input.
26 ~ 30 V1 ~ V5 In Those voltages are used for generating the stepped
pulse of the LCD drive signals.
31, 32 LP, XCLS — Not used
33 VDD In DVDD (+5 V) source
34, 35 FR, DO — Not used
36 RS In Data/command determination terminal.
High: data, Low: command
37 R/W In Read/Write terminal. High: read, Low: write
Chip enable signal.
38 E In High: enable, the writing is done at fall edge.
Low: disenable
39 ~ 42 DB0 ~ DB3 — Not used. Connected to GND (0 V)
43 ~ 46 DB4 ~ DB7 In/Out Data bus
47 ~ 62 COM1 ~ COM16 Out Common signal/output

— 6 —
FILTER BLOCK
Since the sound signals from the CPU is stepped waveforms, the filter block is added to smooth the waveforms.
POWER AMPLIFIER (IC101: LA4598)
The power amplifier is a two-channel amplifier with standby switch.
The following table shows the pin function of IC101.
Pin No. Terminal In/Out Function
1 Power GND In Ground (0 V) source
2 Ch1 B.S. — Terminal for a bootstrap capacitor
3 Ch1 OUT Out Channel 1 output
4 VCC In +9 V source
5 Ch1 N.F. In Negative feedback input
6 Ch1 IN In Channel 1 output
7 D.C — Terminal for a bootstrap capacitor
8 Pre GND In Ground (0 V) source
9 Stand by In Power control signal input. 0 V:Off, +9 V: On
10 Ch2 IN In Not used. Connected to ground (0 V)
11 Ch2 N.F. In Negative feedback input
12 Ch2 OUT Out Channel 2 output
13 Ch2 B.S. — Terminal for a bootstrap capacitor
14 NC — Not used
Amp.
LA4598 Filter
Block CPU
MSM6755C-17

— 7 —
Item Measuring Instrument
Vop voltage setting Voltmeter
3) Equipment connection/Procedure
Vop voltage setting
Input
Connection Input
Point Input Signal Adjust Output Connection Output Point Adjust for
VR1 Voltmeter TP1 Adjust for 4.1 ~ 4.0 V reading
on voltmeter under the
temparature 20 ~ 25 °C.
Make fine adjustment ac-
cording to the following in-
struction.
Watching the LCD at a 36.6°angle to the horizontal, adjust Vop
voltage so that unenergized segments are seen dimly.
ADJUSTMENT
MAIN PCB
1) Items to be adjusted:
2) Adjustment and Test Point Locations
(TOP VIEW) (BOTTOM VIEW)
TP1
VR1
36.6°
LCD
Eye
Output
Set Voltmeter
TP1

— 8 —
MAJOR WAVEFORMS
1Clock pulse
MSM6755C-17 pin 32
1
2+5 V source DVDD
JB connector pin 4
3APO signal
JB connector pin 8
2
3
4Button scan signal KO6
JA connector pin 14
5Button scan signal KO7
JA connector pin 15
4
5
6LCD common signal COM9
KS0066U-10B pin 55
7LCD common signal COM10
KS0066U-10B pin 56
6
7

— 9 —
3
2
7
6
4
5
1
Top View
PRINTED CIRCUIT BOARDS
Main PCB JCM444-MA1M
Bottom View

— 10 —
SCHEMATIC DIAGRAMS
Main PCB JCM444-MA1M
1
5
4
2
3
7
6

— 11 —
Sub PCBs JCM444-MA2M/MA3M

— 12 —
Keyboard PCBs JCM4911K-KY1M/KY2M

— 13 —
LCD
SegmentCommon
COM7
COM6 COM5
COM4
COM3
COM2 COM1 SEG2
COM11 COM12
SEG39 SEG40
COM10 COM9
COM14 COM15
COM16
SEG11
NC NC NC
COM16
SEG3
SEG4 SEG5
SEG6 SEG7 SEG8
SEG9
SEG10 SEG21
SEG22
SEG23 SEG24 SEG25
SEG26
SEG27
SEG28
SEG29 SEG30 SEG31 SEG32 SEG33 SEG34 SEG35 SEG36
SEG37 SEG38
SEG39 SEG40
SEG1
SEG12
SEG13 SEG14
SEG15 SEG16 SEG17
SEG18 SEG19 SEG20 SEG21 SEG22 SEG23
COM15 COM14 COM13 COM12 COM11
COM10 COM9 COM16
COM15 COM14 COM13
COM7 COM6 COM5 COM4 COM3 COM2
COM1
SEG2
COM11 COM12
SEG39 SEG40 COM10
COM9 COM14
COM15
COM16
SEG11
NC NC
NC
COM16
SEG3
SEG4
SEG5
SEG6 SEG7 SEG8
SEG9
SEG10 SEG21 SEG22 SEG23
SEG24 SEG25
SEG26
SEG27 SEG28
SEG29
SEG30
SEG31 SEG32
SEG33
SEG34
SEG35
SEG36 SEG37 SEG38
SEG39
SEG40
SEG1
SEG12 SEG13
SEG14
SEG15
SEG16
SEG17
SEG18
SEG19 SEG20
SEG21 SEG22
SEG23 COM15 COM14
COM13 COM12 COM11
COM10
COM9 COM16 COM15 COM14 COM13

— 14 —
EXPLODED VIEW
18
17
19
22
6
R-1
5
12 7
10
9
11 13 14 15
16
8
1
2
23
4
21
20
4
R-3
R-5
3
R-4
R-2

— 15 —
Notes: This parts list does not include the cosmetic parts, which
parts are marked with item No. "R-X" in the exploded
view.
Contact our spare parts department if you need these
parts for refurbish.
1. Prices and specifications are subject to change with-
out prior notice.
2. As for spare parts order and supply, refer to the
"GUIDEBOOK for Spare parts Supply", published
seperately.
3. The numbers in item column correspond to the same
numbers in drawing.
PARTS LIST
CTK-431

— 16 —
Item Code No. Part Name Specification QR
Main PCB
16926 7070 PCB/ASSY (MA1M) M240832*1 1B
LSI1 2012 5603 LSI/MC (CPU) MSM6755B-17 1A
LSI2 2012 5611 LSI/MASK-ROM UM23C2101M-7384/Q 1A
LSI3 2012 5935 LSI/LCD DRIVER KS0066U-10B 1A
IC12012 1883 IC/MOS (RESET IC) RN5VD40AA-TR 2B
Q1,Q2 2252 1239 TRANSISTOR 2SC4081T106Q 1B
Q3 2250 1162 TRANSISTOR 2SA1576AT106R 1B
VR12775 0994 POTENTIOMETER EVN-D8AA03B53 1B
X12590 2100 OSCILLATOR/CERAMIC CSACS20.00MX040-TC 1B
Sub PCB
26927 5070PCB/ASSY (MA2,3M) M241005*1 1B
IC101 2114 2891 IC/LINEAR (POWER AMP) LA4598 1A
IC102 2252 1248 IC/POTOCUPPLER HCPL-261A 1A
Q102 2250 1591 TRANSISTOR 2SB1237TV2R 1A
Q103~Q105 2250 1592 TRANSISTOR 2SC1740STPR 3A
Q101 2250 1593 TRANSISTOR 2SD1858TV2R 1A
D101 2390 3021 DIODE/SHOTTKY SRT14 1C
D102 2390 3018 DIODE 1T21C
D104~D113 2390 1344 DIODE 1SS133T-77-T 10C
D103 2360 2044 DIODE/ZENER MTZJ6.2A-T77-T 1A
J101 3612 0665 JACK (PHONE) YKB21-5006 1B
J102 3501 7049 JACK (POWER) HEC2305-01-330 1B
J103 3501 4816 JACK (MIDI) YKF51-5051 1B
Keyboard PCBs
36926 7050 PCB/ASSY M140749*1 1C
D701 - D749 2301 0101 DIODE 1S2473T-77-T 49B
Mechanical Parts
43831 0665 SPEAKER 10G42AFA 1B
53335 6823 LCDLD-B10272E 1B
66926 7200 RUBBER/INTERCONNECTOR M440584-2 2C
76927 6040 SPACER/455A M440810-1 1C
86927 6050 SPACER/455B M440811-1 1C
96927 6060 FILM/LEXAN M440812-1 1C
10 6927 5060 EL M340996*1 1B
116909 5890 SWITCH/SLIDE KONB CSB-12D 1B
12 6921 5031 KNOB M311859-1 1B
13 6927 6070 RUBBER/BUTTON M240796-2 1B
14 6927 6080 RUBBER/BUTTON M240797-2 1B
15 6927 6090 RUBBER/BUTTON M240798-2 1B
16 6927 6100 RUBBER/BUTTON M240799-2 1B
17 6922 2720 KEY SET/LT WHITE M312118*1 3A
18 6922 2730 KEY SET/LT WHITE M312118*2 1A
196922 2740 KEY SET/LT BLACK 10P M111726-1 2A
20 6926 0670 RUBBER/CONTACT M240549-1 3A
21 6926 0680 RUBBER/CONTACT M240550-1 1A
22 6906 9611 PANEL/DISPLAY M340789-2 1C
23 6925 4500 COVER/BATTERY M340528*1 1B
Accessory
6906 8752 STAND/NOTE M340629B*2 1B
Notes: Q–Quantity per unit
R– Rank

CASIO TECHNO CO.,LTD.
Overseas Service Division
Nishi-Shinjuku Kimuraya Bldg. 1F
5-25, Nishi-Shinjuku 7-Chome
Shinjuku-ku, Tokyo 160-0023, Japan