Casio CTK-450 User manual

(with price)
CTK-450
ELECTRONIC KEYBOARD
R
CTK-450

CONTENTS
SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
DISASSEMBLE INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
CIRCUIT DESCRIPTION
Key and Switch Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
CPU (MSM6567-15) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Filter Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Mute Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Power Amplifier (LA4598) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Power Supply Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
PCB VIEW AND MAJOR WAVEFORMS . . . . . . . . . . . . . . . . . . . . . . . . 10
EXPLODED VIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
IC AND TRANSISTOR LEAD IDENTIFICATIONS . . . . . . . . . . . . . . . . 13
PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

— 1 —
General
Number of Keys: 61
Polyphonic: 16-note
Preset Tones: 64
Auto-Rhythms: 64
Auto-Accompaniment: CASIO Chord/Fingered
Auto-Play Tunes: Songs: 32 (Melody ON/OFF)
Free Sessions: 32
Terminals: PHONE/OUTPUT Jack [Output Impedance: 40 Ω, Output Voltage:
3.5V(rms)MAX], AC Adaptor Jack (DC9V)
Built-In Speakers: 10 cm dia. 1.5W Input Rating: 1 pec.
Power Source: 3-way AC or DC source
AC: AC adaptor AD-5
DC: 6 D size dry batteries
Battery life: Approx. 2 hours (SUM-3/R6P)
Approx. 4 hpurs (AM-3/LR6)
Car battery: Required optional car adaptor CA-5
Auto Power Off: Approx. 6 minutes after the last operation
Power Consumption: 7.0 W
Dimentions: 86 x 920 x 291 mm (HWD)
(3-3/8 x 36-1/4 x 11-7/16 inches) (HWD)
Weight: 3.5 kg (7.7 lbs) excluding batteries
Standard Accessory: Music stand, Song book
Electrical
Current Drain with 9V DC:
No Sound Output 130 mA ±20%
Maximum Volume 400 mA ±20%
with keys C3 to C4 pressed in Clarinet tone,
Volume; Maximum
Line Output Level (Vrms with 47 KΩload each cannel): 650 mV ±20%
with key C6 pressed in Clarinet tone
Phone Output Level (Vrms with 8 Ωload each channel): 120 mV ±20%
with key C6 pressed in Clarinet tone
Speaker Input Level: 1400 mV ±20%
with key C6 pressed in Clarinet tone
Minimum Operating Voltage: 5.7 V
SPECIFICATIONS

— 2 —
DISASSEMBLE INSTRUCTIONS
Note: The keyboard PCBs are fixed to the case by springy clicks instead of by screws.
To disassemble keyboard PCBs
1. Using gentle force, press a click to release the PCB from the click.
A click can be caught in the slit behind of it, or can be deformed if too much force is used.
When a click is caught in the slit, return it to original position with a tweezers.
2. Release the clicks one by one from an end to another along the PCBs.
3. Take off the PCBs.
To reassemble the keyboard PCBs
1. Before assembling the PCBs, check that all clicks are free, and properly aligned.
2. Set the PCBs in the bumps opposite to the clicks.
3. Press down the PCBs until clicking.
When clicks are deformed, screw the PCBs on the case.
The screw is available from our spare parts center.
Code No. 0009 2682 Screw 2.6 x 8

— 3 —
KO0~KO14
KI0~KI7
Keyboard
Switches
Oscillator
Power Supply Circuit
AVDD +5V
VCC +9V
Speaker
Output Jack
Filter
T4/T5
CPU
MSM6567-15
T1/T2/T3
Amplifier
LA4598
Main Volume
Mute Circuit
Reset IC
VDD +5V
M5218APR
T6
S-8053ANO
LEDX6
(APO)
BLOCK DIAGRAM

— 4 —
0IK1IK2IK3IK4IK5IK6IK7IK
0OK rewoP
FFO2C2#C2D2#D2E2F
1OK yalP2#F2G2#G2A2#A2B
2OK deregniF3C3#C3D3#D3E3F
3OK OISAC
drohC 3#F3G3#G3A3#A3B
4OK gnoS4C4#C4D4#D4E4F
5OK 4#F4G4#G4A4#A4B
6OK 5C5#C5D5#D5E5F
7OK 5#F5G5#G5A5#A5B
8OK 6C6#C6D6#D6E6F
9OK 6#F6G6#G6A6#A6B
01OK 7C43210
11OK opmeT
nwoD
.pmoccA
1emuloV
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21OK opmeT
pU .pmoccA 2emuloV
31OK .pmoccA
3emuloV enoTmhtyhR ydoleM FFO/NO /tratS potS/cnyS ni-lliF
41OK .pmoccA 4emuloV
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CIRCUIT DESCRIPTION
Key and Switch Matrix
Nomenclature of Keys
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 —
Pin No. Terminal In/Out Function
1 LEDY0 Out Not used.
2 LVDD1 In +5V source
3 LGND2 In Ground (0V) source
4 ~ 9 LEDX0 ~ LEDX5 Out Not used.
10 LEDX6 Out APO(Auto Power Off) signal output ON: "H" OFF: "L"
11 LEDX7 Out Not used.
12 LVDD2 In +5V source
13 ~ 27 Not used.
28 GND2 In Ground (0V) source
29 COSI In 43.45MHz clock pulse input
30 COSO Out 43.45MHz clock pulse output
31 VDD In +5V source
32 GND2 In Ground (0V) source
33 ~ 35 TEST1 ~ TEST3 Not used. Connected to ground.
36 MI In Not used. Connected to +5V.
37 -RESET In Reset signal input
38 AVDD In Ground (0V) source for internal DAC
39 OUT Out Sound waveform output
40 AGND In Ground (0V) source for internal DAC
41 ~ 48 KI0 ~ KI7 In Input terminals for keys and switches
49 ~ 63 KO0 ~ KO14 Out Key and switch scan signal output
64 ~ 72 Not used.
73 LGND1 In Ground (0V) source
74 ~ 80 Not used.
CPU (MSM6567-15)
Containing sound data ROM and DAC (Digital to Analog Convertor), the CPU provides sound waveform in
accordance with the pressed key and the selected tone.
The following table shows pin function of the LSI.

— 6 —
Filter Block
Since the sound signal from the CPU is a stepped waveform, the filter block is added to smooth the
waveform.
Mute Circuit
The mute circuit removes noise from the sound signal just before the signal fades away. The circuit
detects amplitude of the decaying sound signal by amplifing it by 1000 times, and transistor T6 flows the
signal into the ground when the amplitude decays almost zero.
MSM6567-15
CPU
To mute circuit
To main volume
Sound signal from filter block
+0.5V at the minimum amplitude (no sound)
-2.7V at the maximum amplitude

— 7 —
Power Amplifier (LA4598)
LA4598 is a 2-channel power amplifier with stand-by switch.
The following table shows the pin functiion of the power amplifier.
Pin No. Terminal In/Out Function
1 Power GND In Ground (0V) source
2 Ch1 B.S. Terminal for bootstrap capacitor
3 Ch1 OUT Out Channel 1 output
4 VCC In +9V source
5 Ch1 N.F. In Negative feedback input
6 Ch1 IN In Channel 1 input
7 D.C. Terminal for decoupling capacitor
8 Pre GND In Ground (0V) source
9 Stand by In Power control signal input. 0V: OFF, +9V: ON
10 Ch2 IN In Channel 2 input
11 Ch2 N.F. In Negative feedback input
12 Ch2 OUT Out hannel 2 output
13 Ch2 B.S. Terminal for bootstrap capacitor
14 NC Not used.
6
5
8
7
10
11 13
12
9
4
1
3
2
Input
Amp. Pre-drive
Amp. Power
Amp.
TSD protector
Stand by
Bias circuit
Input
Amp. Pre-drive
Amp. Power
Amp.
Ch1 IN
Ch1 NF
Pre GND
D.C.
Ch2 IN
CH2 NF
CH2 BS
CH1 OUT
POWER GND
VCC
STAND BY
CH2 OUT
CH2 BS
Block Diagram

— 8 —
Power Supply Circuit
The power supply circuit generates three voltages - VDD (+6.0V) for the CPU and the reset IC, AVDD
(+6.0V) for the analog circuit, and VCC1 (+8.6V) for the pilot lamp and the power amplifier.
When turning power on, the 100µcapacitor makes transistor T2 on first then the CPU provides transistor
T2 "High" of APO signal to keep it being on.
HOW TO GET POWER IN OPENING TOP PANEL
1. Remove the mode switch contact from the top panel.
2. Make short-circuit Aand Bwith a wire as shown below.
3. Connect an AC adaptor to the DC jack.
4. Place the contact on carbon paint of the mode switch.
5. Align the contact onto OFF position.
6. Slide the contact to PLAY position so that the pilot lamp lights up.
7. Take the contact off the carbon paint.
The unit will operate until disconnecting the AC adaptor or automatic power off, and it sounds at full
volume.
AB