Casio CTK-541 User manual

ELECTRONIC KEYBOARD

CTK-541

JULY.1999

CTK-541

CONTENTS

Specifications ................................................................................................................................... 1

Block Diagram.................................................................................................................................. 3

Circuit Description ............................................................................................................................ 4

Adjustment ....................................................................................................................................... 8

Major Waveforms ........................................................................................................................... 10

Printed Circuit Boards .................................................................................................................... 11

Schematic Diagrams ...................................................................................................................... 15

Exploded View ............................................................................................................................... 19

Parts List ........................................................................................................................................ 20

— 1 —

SPECIFICATIONS

GENERAL

Keyboard: 61 standard-size keys, 5 octaves (with touch response on/off)

Tones: 100

Polyphony: 16 notes maximum (8 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 (ACCOMP), RIGHT ON/

OFF (MELODY)

Display

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

Song bank status: PLAY, PAUSE, REW, FF

Staff: 5 octaves with sharp and flat indications

Keyboard: 5 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

Sustain terminal: Standard jack

Phones/Output terminal: Stereo standard jack

Output Impedance: 50 Ω

Output Voltage: 3.5 V (RMS) MAX

Power supply terminal: 9 V DC

Power supply DC 9 V

Batteries: 6 D-size batteries

Battery life: Approximately 5 hours on manganese batteries

Auto power off: Turns power off approximately six minutes after last key operation. Enabled

under battery power only, can be disabled manually.

Speaker output: 2.0 W + 2.0 W

Power consumption: 9 V --- 7.7 W

Dimensions (HWD): 961 ×376 ×143 mm (37-7/8 ×14-13/16 ×5-5/8 inches)

Weight: Approximately 5.7 kg (12.6 lbs) (without batteries)

— 2 —

ELECTRICAL

Current drain with 9 V DC: Nominal Limit

No sound output 330 mA 330 mA ±20%

Maximum volume 990 mA 990 mA ±20%

with 16 keys C1 to D3 pressed in Synth-Lead 1

Volume: Maximum, Touch response: ON(Velocity MAX)

Phone output level (Vrms with 8 Ωload each channel): L 240mV 240 mV ±20%

with key C3 pressed in Synth-Lead 1 R 250mV 250 mV ±20%

Speaker output level (Vrms with 4 Ωload each channel):

with key G1 pressed in Synth-Lead 1 L/R 2500mV 2500 mV ±20%

Output level (Vrms with 47 KΩload each channel): L 2300mV 2300 mV ±20%

with key C2 pressed in Synth-Lead 1 R 2400mV 2400 mV ±20%

Minimum operating voltage: 6.3V 7.0V

— 3 —

BLOCK DIAGRAM

CPU

GT913F(T)

LSI1

Keyboard

Buttons

LCD LCD Driver

KS0066U-10B

LSI3

Reset IC

UPD6379GR-E1

IC1

Oscillator

X1, Q1

Power Supply Circuit

Q201 ~ Q203, Q207, Q208, D205

Power Amp.

TA8248K

IC201

Filter (L)

Q206

Filter (R)

Q205

Phone/Output

VC VCC DVDD AVDD

APO

DC + 9V IN

DB4 ~ DB7

MIDI IN

MIDI OUT

COM1 ~ COM16

SEG1 ~ SEG40

R/W

EKI0,KI1

FI8~FI10 FI0 ~ FI7

KC0 ~ KC7

MD0 ~ MD15

MA0 ~ MA19 ROM(8M-bit)

MSM538002E-

N8GS - KDR1

LSI2

Power Switch

— 4 —

CIRCUIT DESCRIPTION

KEY MATRIX

NOMENCLATURE OF KEYS

KI0 KI1 KI2 KI3 KI4 KI5 KI6 KI7

KO0 C2 G#2 E3 C4 G#4 E5 C6 G#6

KO1 C#2 A2 F3 C#4 A4 F5 C#6 A6

KO2 D2 A#2 F#3 D4 A#4 F#5 D6 A#6

KO3 D#2 B2 G3 D#4 B4 G5 D#6 B6

KO4 E2 C3 G#3 E4 C5 G#5 E6 C7

KO5 F2 C#3 A3 F4 C#5 A5 F6

KO6 F#2 D3 A#3 F#4 D5 A#5 F#6

KO7 G2 D#3 B3 G4 D#5 B5 G6

KO8 —+0

KO9 321

KO10 6 5 4 Rhythm Tone

KO11 9 8 7 Fingered Normal Off

KO12 FF Right Stop Left REW

Tempo

Down Tempo

Start/

Stop Synchro/

Fill-In Chord

Book Accomp

Volume

Transpose/

Tune/MIDI

Song

Bank

CASIO

Chord

Play/

Pause

Volume

Down Volume

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

F3 G3 A3 B3 C4 D4 E4 F4 G4 A4 B4 C5 D5 E5 F5 G5 A5 B5 C6

D#3

C2 D2 E2 F2 G2 A2 B2 C3 D3 E3 B6A6G6F6E6D6 C7

C#3A#2G#2

F#2D#2

C#2 A#6

G#6F#6D#6

C#6

— 5 —

CPU (LSI1: GT-913F)

The 16-bit CPU contains a 1k-byte RAM, three 8-bit I/O ports, two timers, a key controller and serial interfaces.

The CPU detects key velocity by counting the time between first-key input signal FI and second-key SI from

the keyboard. The CPU reads sound data and velocity data from the sound source ROM in accordance with

the selected tone; the CPU can read rhythm data simultaneously when a rhythm pattern is selected. Then the

CPU provides 16-bit serial sound data to the DSP. The CPU also controls MIDI input/output and stores

sequencer data into the working storage RAM.

The following table shows the pin functions of LSI1.

Pin No. Terminal In/Out Function

1 TXD0 Out MIDI signal output

2 RXD0 In MIDI signal input

3 SCK0 Out APO (Auto Power Off) signal output

4, 5 TXD/P13, In/Out Data bus for the LCD driver

RXD/P14

6 SCK1 Out 1 MHZ synchronizing pulse output

7 AVCC In CVDD (+5 V) source

AC adaptor detection terminal.

8 AN0 In +5 V when the keyboard is powered by batteries and becomes 0 V

to cancel the APO function when AC adaptor is connected.

9 AN1 In Input from pitch bender

10 AGND In Ground (0 V) source

11 BCK Out Bit clock output

12 SO Out Serial sound data output

13 LRCK Out Word clock output

14 GND In Ground (0 V) source

15, 16 XLT0, XLT1 In/Out 30 MHz clock input/output

17 VCC In +5 V source

18, 19 MOD0, MOD1 In Mode selection terminal

20 RSTB In Reset signal input

21 NMI In Power ON signal input

22 INT/P10 In/Out Data bus for the LCD driver

23 ~ 30 FI0 ~ FI3 In Terminal for key input signal

SI0 ~ SI3

31 ~ 38 KC0 ~ KC7 Out Terminal for key scan signal

39 ~ 50 FI4 ~ FI9 In Terminal for key input signal

SI4 ~ SI9

51 FI10 In Terminal for button input signal

52 SI10/P23 Out Chip enable signal for the LCD driver

53 ~ 55 KI0 ~ KI2 In Terminal for button input signal

56 MWNB Out Write enable signal for the DSP

57 ~ 76 MA0 ~ MA19 Out Address bus

77 MCSB0 Out Chip enable signal output for the sound source ROM

78 MCSB1 Out Not used

79 MCSB2 Out Chip enable signal output for the DSP

— 6 —

Pin No. Terminal In/Out Function

80 VCC In +5 V source

81 GND In Ground (0 V) source

82 MRDB Out Read enable signal output for the sound source ROM

83 ~ 98 MD0 ~ MD15 In/Out Data bus

99 PLE Out Reset signal output for the DSP

100 P17 In/Out Data bus for the LCD driver

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 KS0066U-10B.

Pin No. Terminal In/Out Function

1 ~ 22,

63 ~ 80

23 VSS — GND (0 V) source

Terminals for the built-in clock pulse generator. The 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

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

SEG1 ~ SEG40 Out Segment signal output

24, 25 OSC1, OSC2 In/Out

36 RS In

— 7 —

FILTER BLOCK

Since the sound signals from the CPU is stepped waveforms, the filter block is added to smooth the waveforms.

POWER AMPLIFIER (IC201: TA8248K)

The power amplifier is a two-channel amplifier with standby switch.

The following table shows the pin function of IC201.

Pin No. Terminal In/Out Function

1 NC — Not used

2 B.S.2 — Terminal for a bootstrap capacitor

3 OUT2 Out Channel 2 output

4 VCC In +9 V source

5 OUT1 Out Channel 1 output

6 B.S.1 — Terminal for a bootstrap capacitor

7 Power GND In Ground (0 V) source

8 Stand by In Power control signal input. 0 V: Off, +9 V: On

9 DC — Terminal for a decoupling capacitor

10 NF1 In Negative feedback input

11 IN1 In Channel 1 input

12 IN2 In Channel 2 input

13 NF2 In Negative feedback input

14, 15 Pre GND In Ground (0 V) source

Amp.

TA8248K Filter

Block CPU

MSM6755B-17

— 8 —

ADJUSTMENT

MAIN PCB

1) Items to be adjusted:

2) Adjustment and Test Point Locations

Item Measuring Instrument

Vop voltage setting Voltmeter

VR1

(BOTTOM VIEW)

Test point

(TOP VIEW)

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