Casio CTK-680 Service Manual page 6

NOMENCLATURE OF KEYS
C#2 D#2 F#2 G#2 A#2 C#3
C2 D2 E2 F2 G2 A2 B2 C3 D3
BUTTON MATRIX
KO0 MODE
KO1 TEMPO UP
KO2
MAGICAL
KO3
PRESET
KO4 DEMO
SYNCHRO/
KO5
ENDING
KO6
KO7
ACCOMP
KO8
VOLUME
KO9
POWER SUPPLY CIRCUIT
The power supply circuit generates six voltages as shown in the following table. VDD voltage is always
generated. The others are controlled by APO signal output from the CPU.
Name Voltage
VDD +5.0 V
DVDD +5.2 V
AVDD +5.0 V
LVDD +5.0 V
VCC +12 V
VC +12 V
D#3 F#3 G#3 A#3
C#4 D#4
E3
F3 G3 A3 B3 C4 D4 E4
KI1 KI2
PAD A
TEMPO DOWN
LAYER
TOUCH
RESPONSE
VAR/FILL-IN
9 8
— 4
MULTI-TRACK
MEMORY
0 1
CPU, Reset IC, Working storage RAM, Gate array
DSP, Key controller, Sound source ROM, Effect RAM
DAC, Filter
LED Driver
Pilot lamp
Power amplifier
F#4 G#4 A#4 C#5 D#5 F#5 G#5 A#5
F4 G4 A4 B4 C5 D5 E5 F5 G5
KI3
PAD B
START/STOP
RHYTHM
DIGITAL EFFECT
NORMAL/FILL-IN
7
5
TRANSPOSE/
TUNE/MIDI
2
For operation of
— 6 —
D#6 F#6 G#6 A#6
C#6
A5 B5 C6 D6 E6 F6 G6 A6 B6
KI4
PAD D
PAD C
TONE
SPLIT
REGISTRATION
INTRO
+
6
MIXER
3
C7