ELECTRONIC KEYBOARD
CT-870
CT-870
VOLUME
SLOW
FAST
MELODY CONTROLLER
PORTAMENTO
SPLIT
LAYER
RHYTHM
TONE
MULTI FUNCTION DISPLAY
MAIN
VOLUME
FULL RANGE
CHORD
FINGERED
CASIO
CHORD
MAX
MIN
MODE
POWER
REVERB
STAGE
HALL
ROOM
45
6
12
3
REGISTRATION
SAVE
ACCOMP
VOLUME
TEMPO
NORMAL/
VARIATION
INTRO/
FILL-IN
SYNCHRO/
ENDING
START/
STOP
12
3
45
6
78
9
0
|
{
/
¢
DEMO
TRANSPOSE/
TUNE/MIDI
SONG
MEMORY
TOUCH
RESPONSE
100
TONES
100
RHYTHMS
PIANO
00 PIANO
01 HARD PIANO
02 STUDIO PIANO
03 HONKY-TONK
04 ELEC PIANO 1
05 ELEC PIANO 2
06 ELEC PIANO 3
07 CHORUSED EP
08 HARPSICHORD
09 CLAVELECTRO
10 MUSIC BOX
11 VIBRAPHONE
12 MARIMBA
13 THUMB PIANO
ORGAN
14 ELEC ORGAN 1
15 ELEC ORGAN 2
16 ELEC ORGAN 3
17 JAZZ ORGAN
18 ROCK ORGAN 1
20 CHURCH ORGAN
21 ACCORDION
22 BANDONEON
23 REED ORGAN
24 HARMONICA
25 GUT GUITAR
26 ACOUS GUITAR
27 JAZZ GUITAR
28 ELEC GUITAR
29 MUTE GUITAR
30 DIST GUITAR
31 HARP
32 BANJO
33 WOOD BASS
19 ROCK ORGAN 2
34 ELEC BASS 1
35 ELEC BASS 2
36 FRETLESS BASS
37 SLAP BASS
38 SYNTH-BASS 1
39 SYNTH-BASS 2
ORCHESTRA/ENS
40 VIOLIN
41 CELLO
42 PIZZICATO STR
43 TIMPANI
44 ORCHESTRA HIT
45 STRINGS 1
46 STRINGS 2
47 SYNTH-STR 1
48 SYNTH-STR 2
49 CHOIR
50 SYNTH-VOICE
BRASS
51 TRUMPET
52 TROMBONE
53 TUBA
54 MUTE TRUMPET
55 FRENCH HORN
56 BRASS
REED/PIPE
57 SYNTH-BRASS
58 SOPRANO SAX
60 TENOR SAX
61 BARITONE SAX
62 OBOE
63 CLARINET
64 PICCOLO
65 FLUTE
66 RECORDER
67 PAN FLUTE
68 WHISTLE
SYNTH-LEAD
69 SYNTH-LEAD 1
70 SYNTH-LEAD 2
71 SYNTH-LEAD 3
72 CALLIOPE
73 POWER LEAD
74 FIFTH LEAD
75 BASS+LEAD
76 BOTTLE LEAD
77 FANTASY
78 WARM PAD
80 SPACE CHORUS
81 GLASS HARMONICA
82 COUNTRY FARM
83 POWER STRINGS
84 DREAM PAD
85 PEARL DROP
86 SOUNDTRACK
87 CRYSTAL
88 ATMOSPHERE
ORIENTAL
89 COSMIC SOUND
90 SPACE
91 SYNTH-SFX
92 ERHU
93 ZHENG
94 YANG QIN
95 DIZI
96 SHENG
PERCUSSION
97 PERCUSSION 1
98 PERCUSSION 2
99 PERCUSSION 3
CHROMATIC PERC
GUITAR/BASS
59 ALTO SAX
79 SYNTH-ENS
SYNTH-PAD
POPS I
00 NICE GROOVE
01 POPS 1
02 BALLAD
03 POP BALLAD
04 GROOVE POP
05 RAP POP
06 POP REGGAE
07 SOUL BALLAD
08 POPS 2
09 POP WALTZ
10 16 BEAT 1
11 16 BEAT 2
12 16 BEAT 3
13 8 BEAT 1
14 8 BEAT 2
15 8 BEAT 3
16 POPS 3
17 POPS 4
18 POP FUSION
20 ROCK WALTZ
21 SLOW ROCK 1
22 SLOW ROCK 2
23 SOFT ROCK 1
24 SOFT ROCK 2
25
FOLKIE POP
26
POP ROCK
27
60's SOUL
28
FOLK ROCK
29
30 ROCK 1
31 ROCK 2
32 ROCK 3
33 RIFF ROCK
34 HEAVY METAL
35 50's ROCK
36 TWIST
37 N'AWLINS R&R
38 CHICAGO BLUES
39 R&B
JAZZ/FUSION
40 BIG BAND
41 SLOW SWING
42 SWING
43 FOX TROT
44 JAZZ WALTZ
45 MODERN JAZZ 1
46 MODERN JAZZ 2
47 ACID JAZZ
48 LATIN FUSION
49 FUSION
50 TECHNO
DANCE/FUNK
51 EURO BEAT
52 TRANCE
53 DISCO 1
54 DISCO 2
55 HOUSE
56 RAP
57 RAVE
59 FUNK 2
60 POLKA 1
61 POLKA 2
62 MARCH 1
63 MARCH 2
64 SLOW WALTZ
65 VIENNESE WALTZ
66 WALTZ
67 SIRTAKI
68 SERENADE
LATIN I
69 TANGO
70 BOSSA NOVA 1
71 BOSSA NOVA 2
72 SAMBA 1
73 SAMBA 2
74 JAZZ SAMBA
75 MAMBO
76 RHUMBA
77 CHA-CHA-CHA
78 MERENGUE
80 REGGAE 1
81 REGGAE 2
82 PUNTA
83 CUMBIA
84 PASODOBLE
85 RUMBA CATALANA
86 SEVILLANA
87 SKA
88 TEX-MEX
VARIOUS II
89 FOLKLORE
90 COUNTRY
91 BLUEGRASS
92 TOWNSHIP
93 SLOW GOSPEL
94 RAI
95 ADANI
96 BALADI
97 ENKA
98 6/4
99 9/8
POPS II
19 LATIN POP
ROCK I
SOFT ROCK 3
ROCK II
58 FUNK 1
EUROPEAN
79 BOLERO
LATIN II/VARIOUS I
MO
DULATION
B
E
N
D
U
P
B
E
N
D
D
O
W
N
-- 2 --
CONTENTS
Page
Specifications ................................................................................................................................ 2
Block Diagram ............................................................................................................................... 3
Circuit Description ......................................................................................................................... 4
Major Waveforms ........................................................................................................................ 11
Printed Circuit Board ................................................................................................................... 12
Schematic Diagrams ................................................................................................................... 13
Exploded View ............................................................................................................................ 17
Parts List ..................................................................................................................................... 19
SPECIFICATIONS
GENERAL
Number of keys:
61
Polyphonic:
24-note (12 for some tones)
Preset tones:
100, with split/layer functions
Keyboard controls:
Touch response: On/Off, Key transpose: 12 steps (F#-C-F)
Auto-rhythms:
100, Tempo control: 40 to 255
Auto-accompaniment:
Mode: CASIO Chord/Fingered Chord/Full Range Chord
Controller: Intro/Fill-In, Synchro/Ending, Normal/Variation
Reverb effects:
Hall/Stage/Room
Registrations:
6, Parameters registered: Tone No. (Normal, Layer, Split, Layer Split),
Rhythm No., Tempo, Accompaniment volume, Chord type, Reverberation
type, Split/Layer settings, Pitch bend range, Basic channel, Local on/off,
Portamento on/off
Song memory:
1, Real-time recording, Memory capacity: Approx. 1200 notes in total
Demo tunes:
1, including -- Mei Wenti (Edward Alstrom)
Tuning control:
440Hz
± 50 cents
Built-in speakers:
12 cm dia. 2.5 W input rating: 2 pcs.
MIDI:
16 multi-channel reception
Terminals:
Phone Jack [Output impedance: 110
, Output voltage: 4.2 V(rms)
MAX], Sustain Jack, MIDI Jacks (IN, OUT), AC Adapter Jack (9 V) ,
Foot volume Jack
Auto power off:
Approximately 6 minutes after the last operation
Power source:
2-way AC or DC source
AC: AC adapter
DC: 6 D size dry batteries
Power consumption:
7.7 W
Dimensions (HWD):
140 x 997 x 376 mm (5-1/2 x 39-5/16 x 14-13/16 inches)
Weight:
5.4 kg (11.9 lbs) without batteries
-- 3 --
KC0 ~ KC7
FI0 ~ FI10
SI0 ~ SI8
Working Storage
RAM (64K-bit)
LSI103
LC3564S-10
MIDI
EA0 ~
EA12
EIO0 ~
EIO7
Sound Source ROM
(16M-bit)
LSI104
MX23C1610PC-
12CA38
LRCK
SO
BCK
D/A Converter
IC106
UPD6379GR
Main
Volume
LED driver
IC105
BA612
Keyboard
MA0 ~ MA19
Power Supply Circuit
Q102 ~ Q109
D106, D108, D109
VCC
AVDD
VDD
LVDD
DVDD
VC
APO
Effect RAM
(64K-bit)
LSI105
LC3564S-10
MD0
~
MD7
Speakers
Output
Foot volume
MA0
~
MA12
MA0, MA1
LEDs /
7Seg. LED
LED driver
Q401 ~ Q407
La ~ Lg, Lh
IN
OUT
Reset IC
IC106
RE5VA35AA
RESET
LC0 ~ LC4
Buttons
VDD
Power Switch
SUSTAIN
PA0 ~ PA6
PB0 ~ PB4
CPU
LSI101
UPD913GF-3BA
BCK, SO, LRCK
DSP
LSI102
HG51B277FB
FI9, FI10
KI0 ~ KI2
SI9
MD0 ~ MD15
Amp.
IC101
M5218APR
Filter
Q115 ~ Q118
Power Amplifier
IC102
LA4598
BLOCK DIAGRAM
-- 4 --
CIRCUIT DESCRIPTION
KEY MATRIX
KC0
KC1
KC2
KC3
KC4
KC5
KC6
KC7
FI0
C2 (1)
C#2 (1)
D2 (1)
D#2 (1)
E2 (1)
F2 (1)
F#2 (1)
G2 (1)
SI0
C2 (2)
C#2 (2)
D2 (2)
D#2 (2)
E2 (2)
F2 (2)
F#2 (2)
G2 (2)
FI1
G#2 (1)
A2 (1)
A#2 (1)
B2 (1)
C3 (1)
C#3 (1)
D3 (1)
D#3 (1)
SI1
G#2 (2)
A2 (2)
A#2 (2)
B2 (2)
C3 (2)
C#3 (2)
D3 (2)
D#3 (2)
FI2
E3 (1)
F3 (1)
F#3 (1)
G3 (1)
G#3 (1)
A3 (1)
A#3 (1)
B3 (1)
SI2
E3 (2)
F3 (2)
F#3 (2)
G3 (2)
G#3 (2)
A3 (2)
A#3 (2)
B3 (2)
FI3
C4 (1)
C#4 (1)
D4 (1)
D#4 (1)
E4 (1)
F4 (1)
F#4 (1)
G4 (1)
SI3
C4 (2)
C#4 (2)
D4 (2)
D#4 (2)
E4 (2)
F4 (2)
F#4 (2)
G4 (2)
FI4
G#4 (1)
A4 (1)
A#4 (1)
B4 (1)
C5 (1)
C#5 (1)
D5 (1)
D#5 (1)
SI4
G#4 (2)
A4 (2)
A#4 (2)
B4 (2)
C5 (2)
C#5 (2)
D5 (2)
D#5 (2)
FI5
E5 (1)
F5 (1)
F#5 (1)
G5 (1)
G#5 (1)
A5 (1)
A#5 (1)
B5 (1)
SI5
E5 (2)
F5 (2)
F#5 (2)
G5 (2)
G#5 (2)
A5 (2)
A#5 (2)
B5 (2)
FI6
C6 (1)
C#6 (1)
D6 (1)
D#6 (1)
E6 (1)
F6 (1)
F#6 (1)
G6 (1)
SI6
C6 (2)
C#6 (2)
D6 (2)
D#6 (2)
E6 (2)
F6 (2)
F#6 (2)
G6 (2)
FI7
G#6 (1)
A6 (1)
A#6 (1)
B6 (1)
C7 (1)
SI7
G#6 (2)
A6 (2)
A#6 (2)
B6 (2)
C7 (2)
FI9
Intro/
Fill-In
Synchro/
Ending
Portament
Start/
Stop
Registration
1
Registration
2
Registration
3
Registration
4
FI10
Registration
5
Registration
6
Save
Normal/
Variation
Tempo
Up
Tempo
Down
Accomp.
Volume
Up
Accomp.
Volume
Down
KI0
Mode
Rhythm
0
1
4
7
Layer
Split
KI1
Reverb
Tone
2
5
8
Transpose
Tune/MIDI
Demo
KI2
+3
6
9
Song
Memory
Touch
Response
-- 5 --
Key
Second contact (2)
First contact (1)
FI
KC
SI
Note: Each key has two contacts,
the first conatct (1) and second contact (2).
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 from the CPU.
NOMENCLATURE OF KEYS
RESET CIRCUIT
When batteries are set or an AC adapter is connected, the reset IC provides a low pulse to the CPU. The
CPU then initializes its internal circuit, and clears the working storage RAM.
When the power switch is pressed, the CPU receives a low pulse of POWER signal, then the CPU sends
a reset signal to the DSP.
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
B6
A6
G6
F6
E6
D6
C7
C#3
A#2
G#2
F#2
D#2
C#2
A#6
G#6
F#6
D#6
C#6
Reset IC
IC106
RE5VA35AA
DSP
LSI102
HG51B227FB
VDD
Reset signal
VDD
Battery set
RESET
VDD
POWER
From power switch
NMI
PLE
CPU
LSI101
UPD913GF-3BA
Name
Voltage
For operation of
VDD
+5 V
CPU, Reset IC, DSP, Sound source ROM, Working storage RAM, Effect RAM
DVDD
+5 V
Power jack, Sustain jack, MIDI jack
AVDD
+5 V
DAC, Filter
LVDD
+5 V
LED Driver
VCC
+9 V
Power amplifier, Pilot lamp
VC
+9 V
Power amplifier