CASIO ML2 Service Manual
ML-2
(with price)
ELECTRONIC KEYBOARD
ML-2
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
SPECIFICATIONS
General
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)],
AC Adapter Jack (DC 7.5 V)
Power Source: DC: 5 AA size dry batteries
Battery life: Approx. 5 hours (SUM-3/R6P)
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)
(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:
No Sound Output 44 mA ± 20%
Maximum Volume 175 mA ± 20%
with keys B3 and C4 pressed in Flute tone
Volume: Maximum, Rhythm: Rock,
Tempo: Maximum
Speaker Input Level (Vrms with 4 Ω load): 750 mV ± 20%
with key C4 pressed in Flute tone
Volume: Maximum
Output Level (Vrms with 47 kΩ load): 800 mV ± 20%
with key C4 pressed in Flute tone
Volume: Maximum
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
KO0~KO11
KI0~KI7
Illuminated Keyboard
Switches
Oscillator
XL1
Amplifier
AN8053N
IC1
Speaker
CPU
MSM6521-11
LSI1
LEDs
LX0~LX3
LY0~LY7
Power Supply Circuit
T1, D4
VDD 5.6V
AVDD 5.6V
Filter
T2
Output Jack
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
— 2 —
CIRCUIT DESCRIPTION
Key Matrix
KI0 KI1 KI2 KI3 KI4 KI5 KI6 KI7
KO0 F3 F#3 G3 G#3 A3 A#3 B3 C4
KO1 C#4 D4 D#4 E4 F4 F#4 G4 G#4
KO2 A4 A#4 B4 C5 C#5 D5 D#5 E5
KO3 F5 F#5 G5 G#5 A5 A#5 B5 C6
KO4
KO5 Tone 1
KO6 Tone 2 Tone 3 Tone 4 Tone 5
KO7
Melody
Guide
Any Key
Play
Volume
Down
Rhythm
Stop
Demo Play
Volume
Up
Tempo
Down
Rhythm
Select
Keyboard LED Matrix
LY0 LY1 LY2 LY3 LY4 LY5 LY6 LY7
LX0 C6 F5 E5 A4 G#4 C#4 C4 F3
LX1 B5 F#5 D#5 A#4 G4 D4 B3 F#3
Light
On/Off
Tempo
Up
LX2 A#5 G5 D5 B4 F#4 D#4 A#3 G3
LX3 A5 G#5 C#5 C5 F4 E4 A3 G#3
— 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
1 ~ 7 LY1 ~ LY7 Out Keyboard LED drive signal output
8 LVDD1 In +5V source for the built-in LED driver
9 LGND2 In Ground (0V) source for the built-in LED driver
10 ~ 13 LX0 ~ LX3 Out Keyboard LED drive signal output
14 ~ 17 LX4 ~ LX7 Out Not used.
18 LVDD2 In +5V source for the built-in LED driver
19 GND2 In Ground (0V) source
20, 21 COSI, COSO In/Out 21.725 MHz clock pulse input/output
22 VDD In +5V source
23 GND1 In Ground (0V) source
24 ~ 26 TEST1 ~ TEST3 In Not used. Connected to ground.
27 RESET In Reset signal input. Power OFF: 0V, Power ON: +5V
28 AVDD In +5V source for the built-in DAC
29 OUT Out Sound waveform output
30 AGND In Ground (0V) source for the built-in DAC
31 ~ 38 KI0 ~ KI7 In Input terminal for keys and switches
39 ~ 46 KO0 ~ KO7 Out Key and switch scan signal input
47 ~ 58 Not used.
59 LGND1 In Ground (0V) source for the built-in LED driver
60 LY0 In Keyboard LED drive signal output
Filter Block
Since the sound signal from the CPU is a stepped waveform, the filter block is added to smooth the
waveform.
AVDD
T2
2SC1740SQ
C9
R1
AG
R30
R11
AG
— 4 —
C10
AG
R12
C11
R13
R14
C12
AG
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