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CONTENTS
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Circuit Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Major Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Printed Circuit Boards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Schematic Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Exploded View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
SPECIFICATIONS
GENERAL
Model: CASIO CTK-680
Keyboard: 61-key, 5-octave standard size keyboard with touch response (three sensi-
tivity levels and OFF setting)
Tones: 128 tones (Conform with General MIDI level 1) + 8 drum sounds with split/
layer features.
Polyphony: 32 notes maximum
Digital effects: 10
REVERB 1, REVERB 2, REVERB 3, CHORUS, TREMOLO, PHASE
SHIFTER, ORGAN SPEAKER, ENHANCER, FLANGER, LOUDNESS
Musical pads: 120 (four pads ´ 30 sets)
Phrases (22 sets), drums/percussion (7 sets), controller (1 set)
Phrases matche chord
Demo tunes: 3, sequential repeat playback
Auto-accompaniment
Rhythm patterns: 100
Tempo: Adjustable (216 levels, q = 40 to 255)
Chords: 3 types (CASIO Chords, Fingered, Full-Range Chords)
Parts: Rhythm, bass, Chord 1, Chord 2, Chord 3 (adjustable on/off, tone, volume,
pan, effect send, fine tune, coarse tune, expression settings)
Others: Intro, Normal Fill-in, Variation Fill-in, Synchro/Ending
Magical presets: 50 types (Break Beat, Melodycomp, Shadow Drum, Free Session)
Registration memory: 10
Tone changes, tempo setting, auto-accompaniment volume setting, mode,
layer on/off, Mixer settings, effect type, split on/off, rhythm type, auto-
accompaniment rhythm assignment, pad type, chord fingering method,
touch response setting, MIDI settings (including assignable jack settings),
Magical Preset type
Mixer
Number of channels: 16
Parameters:TONE, VOLUME, PAN, EFFECT SEND, FINE TUNE, COARSE TUNE,
EXPRESSION
Multi-track memory
Number of songs: 2
Tracks: 6 (tone, volume, auto accompaniment, magical presets, pan, effect send, fine
tune, coarse tune, expression)
Type: Real-time
Capacity: Approximately 5,200 notes
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Other functions
Transpose: 25 levels (1 octave lower C to 1 octave upper C)
Tuning: Adjustable: A4 = 440 Hz ± 50 cents
Pitch Bender: Adjustable range: ± 12 semitones (bend up, bend down, bend saw) using
musical pads
Modulation: Vibrato setting and performances are done by a Musical pad.
MIDI: 16-timbre multi-timbre receive (General MIDI Level 1)
Speakers: 12 cm diameter ´ 2 (output: 2.5 W + 2.5 W)
Input/Output Jacks
Power supply: 9 V DC
Headphones: Stereo mini jack
Output jacks: Output impedance: 120 W
Output voltage 4.2 V (RMS) MAX
Assignable Jack: Standard jack (sustain, sostenuto, soft, rhythm start/stop)
MIDI terminals: IN, OUT
Power supply: 2-way
Batteries: Six D-size batteries
Battery life: Approximately 5 hours on R20P (SUM-1) manganese batteries
AC adaptor: AD-5 (optional)
Auto power off:Approximately six minutes after last key operation under battery power
(disabled when AC adaptor is connected).
Power consumption: 9 V --- 7.7 W
Dimensions: 94.2 ´ 36.7 ´ 13.5 cm (31-7/16 ´ 14-1/2 ´ 4-3/8 inches)
Weight: 5.2 kg (11.7 lbs) excluding batteries
ELECTRICAL
Current drain with 9 V DC:
No sound output 320 mA ± 20%
Maximum volume
with 12 polyphonic notes in tone No. 022 960 mA ± 20%
Volume; maximum
Phone output level (Vrms with 8 W load each channel): Left channel 115 mV ± 20%
with key C6 pressed in tone No. 042
Line output level (Vrms with 47 kW load each channel): Left channel 1280 mV ± 20%
with key C5 pressed in tone No. 042
Minimum operating voltage: 5.75 V
