Casio CTK-431 User manual

ELECTRONIC KEYBOARD

CTK-431

MIDI

100 SONG BANK KEYBOARD

MUSICAL INFORMATION SYSTEM

SONG BANK CONTROLLER

POWER/MODE

OFF

FINGERED

MAIN

VOLUME SYNCHRO/

FILL-IN START/

STOP TEMPO CHORD BOOK

ACCOMP VOLUME

CASIO CHORD

NORMAL

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

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

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

Fingered CASIO Normal Power Off

Chord

KO12 FF Right Play/ Stop Left Rewind

Pause

CIRCUIT DESCRIPTION

KEY MATRIX

NOMENCLATURE OF KEYS

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

2+5 V source DVDD

JB connector pin 4

3APO signal

JB connector pin 8

4Button scan signal KO6

JA connector pin 14

5Button scan signal KO7

JA connector pin 15

6LCD common signal COM9

KS0066U-10B pin 55

7LCD common signal COM10

KS0066U-10B pin 56

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