CASIO ML2 Service Manual
(with price)
ML-2
ML-2
ELECTRONIC KEYBOARD
CONTENTS
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Circuit Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Schematic Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
PCB View and Major Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Exploded View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
IC and Transistor Lead Identification . . . . . . . . . . . . . . . . . . . . . 11
Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
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SPECIFICATIONS |
General |
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Number of Keys: |
32 |
Illuminated Keys: |
White and Black keys |
Polyphonic: |
2-note |
Preset Tones: |
25 |
Auto-Rhythms: |
12 |
Demonstration Tunes: |
10 |
Lesson Functions: |
3 modes; Demo, Any-Key Play, Melody Guide |
Built-In Speaker: |
8.0 cm dia. 1.0 W Input Rating: 1 pce. |
Terminals: |
Output Jack [Output Impedance: 100 Ω, Output Voltage: 1.6 V (rms)], |
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AC Adapter Jack (DC 7.5 V) |
Power Source: |
DC: 5 AA size dry batteries |
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Battery life: Approx. 5 hours (SUM-3/R6P) |
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AC: AC adapter AD-1 |
Power ON Reminder*: |
3 minutes after the last operation |
Power Consumption: |
1.5 W |
Dimensions: |
57 x 415 x 208 mm (HWD) |
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(2-1/4 x 16-3/8 x 8-1/4 inches) (HWD) |
Weight: |
1.05 kg (2.3 lbs) including batteries |
Electrical
Current Drain with 7.5 V DC: |
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No Sound Output |
44 mA ± 20% |
Maximum Volume |
175 mA ± 20% |
with keys B3 and C4 pressed in Flute tone |
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Volume: Maximum, Rhythm: Rock, |
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Tempo: Maximum |
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Speaker Input Level (Vrms with 4 Ω load): |
750 mV ± 20% |
with key C4 pressed in Flute tone |
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Volume: Maximum |
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Output Level (Vrms with 47 kΩ load): |
800 mV ± 20% |
with key C4 pressed in Flute tone |
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Volume: Maximum |
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Minimum Operating Voltage: |
6.2 V |
*Power ON Reminder
Power ON reminder is sudden audible and light signals, a short melody at maximum volume and lighting up the illuminated keyboard for a few seconds.
Power ON reminder functions three minutes after the last operation, and it repeats every three minutes until turning the switch off or restarting operations.
— 1 —
BLOCK DIAGRAM
Illuminated Keyboard
LX0~LX3
LY0~LY7
LEDs
Output Jack
KO0~KO11
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CPU |
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Amplifier |
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Filter |
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MSM6521-11 |
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AN8053N |
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T2 |
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IC1 |
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LSI1 |
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Speaker
KI0~KI7
VDD 5.6V AVDD 5.6V |
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Power Supply Circuit |
Oscillator |
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T1, D4 |
XL1 |
Switches |
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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 |
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F3 |
G3 |
A3 |
B3 |
C4 |
D4 |
E4 |
F4 |
G4 |
A4 |
B4 |
C5 |
D5 |
E5 |
F5 |
G5 |
A5 |
B5 |
C6 |
— 2 —
CIRCUIT DESCRIPTION
Key Matrix
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KI0 |
KI1 |
KI2 |
KI3 |
KI4 |
KI5 |
KI6 |
KI7 |
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KO0 |
F3 |
F#3 |
G3 |
G#3 |
A3 |
A#3 |
B3 |
C4 |
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KO1 |
C#4 |
D4 |
D#4 |
E4 |
F4 |
F#4 |
G4 |
G#4 |
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KO2 |
A4 |
A#4 |
B4 |
C5 |
C#5 |
D5 |
D#5 |
E5 |
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KO3 |
F5 |
F#5 |
G5 |
G#5 |
A5 |
A#5 |
B5 |
C6 |
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KO4 |
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Volume |
Volume |
Light |
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Down |
Up |
On/Off |
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KO5 |
Tone 1 |
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Rhythm |
Tempo |
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Stop |
Down |
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KO6 |
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Tone 2 |
Tone 3 |
Tone 4 |
Tone 5 |
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Rhythm |
Tempo |
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Select |
Up |
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KO7 |
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Melody |
Any Key |
Demo |
Play |
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Guide |
Play |
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Keyboard LED Matrix
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LY0 |
LY1 |
LY2 |
LY3 |
LY4 |
LY5 |
LY6 |
LY7 |
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LX0 |
C6 |
F5 |
E5 |
A4 |
G#4 |
C#4 |
C4 |
F3 |
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LX1 |
B5 |
F#5 |
D#5 |
A#4 |
G4 |
D4 |
B3 |
F#3 |
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LX2 |
A#5 |
G5 |
D5 |
B4 |
F#4 |
D#4 |
A#3 |
G3 |
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LX3 |
A5 |
G#5 |
C#5 |
C5 |
F4 |
E4 |
A3 |
G#3 |
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— 3 —
CPU (LSI1: MSM6521-11)
Containing a sound data ROM and a DAC (Digital to Analog Converter), the CPU provides sound waveform in accordance with the pressed key and selected tone. The CPU also drives LEDs in the illuminated keyboard directly. The following table shows the pin functions of LSI1.
Pin No. |
Terminal |
In/Out |
Function |
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1 ~ 7 |
LY1 ~ LY7 |
Out |
Keyboard LED drive signal output |
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8 |
LVDD1 |
In |
+5V source for the built-in LED driver |
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9 |
LGND2 |
In |
Ground (0V) source for the built-in LED driver |
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10 ~ 13 |
LX0 ~ LX3 |
Out |
Keyboard LED drive signal output |
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14 ~ 17 |
LX4 ~ LX7 |
Out |
Not used. |
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18 |
LVDD2 |
In |
+5V source for the built-in LED driver |
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19 |
GND2 |
In |
Ground (0V) source |
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20, 21 |
COSI, COSO |
In/Out |
21.725 MHz clock pulse input/output |
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22 |
VDD |
In |
+5V source |
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23 |
GND1 |
In |
Ground (0V) source |
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24 ~ 26 |
TEST1 ~ TEST3 |
In |
Not used. Connected to ground. |
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27 |
RESET |
In |
Reset signal input. Power OFF: 0V, Power ON: +5V |
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28 |
AVDD |
In |
+5V source for the built-in DAC |
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29 |
OUT |
Out |
Sound waveform output |
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30 |
AGND |
In |
Ground (0V) source for the built-in DAC |
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31 ~ 38 |
KI0 ~ KI7 |
In |
Input terminal for keys and switches |
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39 ~ 46 |
KO0 ~ KO7 |
Out |
Key and switch scan signal input |
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47 ~ 58 |
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Not used. |
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59 |
LGND1 |
In |
Ground (0V) source for the built-in LED driver |
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60 |
LY0 |
In |
Keyboard LED drive signal output |
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Filter Block
Since the sound signal from the CPU is a stepped waveform, the filter block is added to smooth the waveform.
AVDD
C9
R1
AG
R30
R11
AG
T2
2SC1740SQ
R12
C10 |
C11 |
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AG
R13 R14
C12
AG
— 4 —
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