Casio CTK-631 User manual

ELECTRONIC KEYBOARD
CTK-631
CTK-631
E
N
T
E
R
C
U
R
S
O
R
ENVELOPE
ENVELOPE
ENVELOPE
AMP
00 FLAT
01-19 VIBRATO
20-49 OTHERS
000-048 DECAY
049-137 SUSTAIN
PITCH
REST
(TIE)3
0123
456
7
TONE
RHYTHM
89
PIANO
BASS
BRASS
REED
STR/ORCHESTRA
ENSEMBLE
ORGAN
GUITAR
CHROMATIC PERC
000 GRAND PIANO
001 BRIGHT PIANO
003 HONKY-TONK
004 ELEC PIANO 1
005 ELEC PIANO 2
006 HARPSICHORD
007 CLAVI
008 CELESTA
009 GLOCKENSPIEL
010 MUSIC BOX
011 VIBRAPHONE
012 MARIMBA
013 XYLOPHONE
015 DULCIMER
014 TUBULAR BELLS
016 DRAWBAR ORGAN
017 PERC ORGAN
018 ROCK ORGAN
020 REED ORGAN
021 ACCORDION
022 HARMONICA
023 BANDONEON
024 NYLON STR GT
025 STEEL STR GT
019 CHURCH ORGAN
002 E GRAND PIANO
027 CLEAN GUITAR
026 JAZZ GUITAR
028 MUTE GUITAR
030 DIST GUITAR
031 GT HARMONICS
032 ACOUSTIC BASS
033 FINGERED BASS
034 PICKED BASS
035 FRETLESS BASS
036 SLAP BASS 1
037 SLAP BASS 2
038 SYNTH-BASS 1
039 SYNTH-BASS 2
041 VIOLA
042 CELLO
040 VIOLIN
043 CONTRABASS
044 TREMOLO STR
045 PIZZICATO STR
047 TIMPANI
048 STRINGS 1
049 STRINGS 2
050 SYNTH-STR 1
051 SYNTH-STR 2
052 CHOIR AAHS
046 HARP
029 OVERDRIVE GT
PIPE
054
SYNTH-VOICE
053 VOICE DOO
055 ORCHESTRA HIT
056 TRUMPET
057 TROMBONE
058 TUBA
059 MUTE TRUMPET
060 FRENCH HORN
061 BRASS
062 SYNTH-BRASS 1
063 SYNTH-BRASS2
064 SOPRANO SAX
065 ALTO SAX
066 TENOR SAX
068 OBOE
069 ENGLISH HORN
067 BARITONE SAX
070 BASSOON
071 CLARINET
073 FLUTE
074 RECORDER
075 PAN FLUTE
076 BLOWN BOTTLE
077 SHAKUHACHI
078 WHISTLE
079 OCARINA
072 PICCOLO
SYNTH-LEAD
SYNTH-PAD
SYNTH-SFX
ETHNIC
080
SQUARE WAVE
081 SAWTOOTH WAVE
082 CALLIOPE
083 CHIFF LEAD
084 CHARANG
085 VOICE LEAD
086 FIFTH LEAD
087 BASS + LEAD
088 NEW AGE
089 WARM PAD
090 POLYSYNTH
091 SPACE CHOIR
092 BOWED GLASS
093 METALLIC PAD
095 SWEEP PAD
094 HALO PAD
096 RAIN DROP
097 SOUNDTRACK
098 CRYSTAL
100 BRIGHTNESS
101 GOBLINS
102 ECHOES
103 SF
104 SITAR
105 BANJO
099 ATMOSPHERE
SYNTH TONE
DRUM SET
USER TONE
PERCUSSIVE
SOUND EFFECTS
107
KOTO
106 SHAMISEN
108 KALIMBA
109 BAG PIPE
110 FIDDLE
111 SHANAI
112 TINKLE BELL
113 AGOGO
114 STEEL DRUM
115 WOOD BLOCK
116 TAIKO
117 MELODIC TOM
118 SYNTH-DRUM
119 REVERSE CYMBAL
121 BREATH NOISE
122 SEASHORE
120 GT FRET NOISE
123 BIRD
124 TELEPHONE
125 HELICOPTER
127 GUNSHOT
128 159
167
199
160
168
126
APPLAUSE
I
N
T
R
O
S
Y
N
C
H
R
O
/
E
N
D
I
N
G
N
O
R
M
A
L
/
F
I
L
L
-
I
N
V
A
R
I
A
T
I
O
N
/
F
I
L
L
-
I
N
START/STOP
POWER TEMPO
VOLUMEMODE
FULL RANGE
BACKLIGHT LCD
DIGITALREVARB
2-WAYMULTI-TRACK MEMORY
CHORD
FINGERED
CASIO CHORD
NORMAL
MAX
MIN
POPS I DANCE / FUNK
POPS
II
00 CLUB POP
01 EURO POP
02 90'S POP
03 8 BEAT
04 8 BEAT BALLAD 1
05 8 BEAT BALLAD 2
06 60'S 8 BEAT
07 16 BEAT
08 16 BEAT BALLAD
09 16 BEAT SHUFFLE
10 POP 1
11 POP 2
12 70'S ROCK 1
13 POP BALLAD
14 16 BEAT SOUL
15 SOUL POP
16 WORLD POP
17 FUSION SHUFFLE
18 6/8 BALLAD
19 50'S R&B BALLAD
ROCK I
20 RAP
21 TRIP HOP
22 TECHNO 1
23 TECHNO 2
24 FUNKY GROOVE
25 DRUM & BASS
26 RAVE
27 TRANCE
28 DISCO
29 FUNK
30 AMERICAN ROCK
31 ROCK
32 70'S ROCK 2
33 RIFF ROCK
34 HEAVY METAL
35 POP ROCK
36 SOFT ROCK
37 SLOW ROCK 1
38 SLOW ROCK 2
39 ROCK WALTZ
ROCK II
JAZZ
40
BIG BAND ROCK
41 SHUFFLE ROCK
42 OLDIES POP
43 OLDIES SHUFFLE
44 BOOGIE-WOOGIE
45 50'S ROCK
46 TWIST
47 NEW ORLNS R&R
48 CHICAGO BLUES
49 R&B
50 BIG BAND 1
51 BIG BAND 2
52 SWING 1
53 SWING 2
54 SLOW SWING
55 ORCH SWING
56 FUNKY JAZZ
57 JAZZ VOICES
58 ACID JAZZ
59 JAZZ WALTZ
EUROPEAN
LATIN
I
60 POLKA 1
61 POLKA 2
62 MARCH 1
63 MARCH 2
64 MARCH 3
65 WALTZ
66 FRENCH WALTZ
67 BALLROOM WALTZ
68 VIENNESE WALTZ
69 TANGO
70 BOSSA NOVA1
71 BOSSA NOVA2
72 SAMBA 1
73 SAMBA 2
74 BEGUINE
75 MAMBO
76 RHUMBA
77 CHA-CHA-CHA
78 MERENGUE
79 BOLERO
LATIN II / VARIOUS I
VARIOUS II
80 SALSA
81 REGGAE
82 PUNTA
83 CUMBIA
84 PASODOBLE
85 RUMBA CATALANA
86 SEVILLANA
87 SKA
88 TEX-MEX
89 TOWNSHIP
90 COUNTRY
91 BLUEGRASS
92 FAST GOSPEL
93 SLOW GOSPEL
94 HAWAIIAN
95 BROADWAY
96 EURO FOX
97 QUICKSTEP
98 ADANI
99 BALADI
GENERAL
REVERB DEMO
TRANSPOSE/
TUNE/MIDI
FREE
SESSION
FREE
SESSION
LAYER
LAYER
SPLIT
CHORD/1 2 3 4 5 6
SPLIT
TOUCH
RESPONSE
TOUCH
RESPONSE
REVERB
GM
HALL
STAGE
ROOM
SYNTH
MIXER
MEMORY
STEP
SYNTH
MIXER
MEMORY
STEP
ACCOMP
VOLUME

CONTENTS
Specifications ................................................................................................................................... 1
Block Diagram.................................................................................................................................. 3
Circuit Description ............................................................................................................................ 4
Adjustment ..................................................................................................................................... 11
Major Waveforms ........................................................................................................................... 13
Printed Circuit Boards .................................................................................................................... 14
Schematic Diagrams ...................................................................................................................... 17
Exploded View ............................................................................................................................... 24
Parts List ........................................................................................................................................ 25

— 1 —
SPECIFICATIONS
GENERAL
Keyboard: 61 standard-size keys, 5 octaves (with touch response on/off)
Drum pads: 6
Tones: 200 (128 General MIDI, 32 synthesized, 8 drum, 32 user); with layer and
split
Rhythm instrument tones: 61
Polyphony: 24 notes maximum (12 for certain tones)
Digital effects: 3 reverb types (HALL, STAGE, ROOM)
Auto accompaniment
Rhythm patterns: 100
Tempo: Variable (216 steps, = 40 to 255)
Chords: 4 fingering methods (NORMAL, CASIO CHORD, FINGERED, FULL
RANGE CHORD)
Rhythm controller: START/STOP, INTRO, NORMAL/NORMAL FILL-IN, VARIATION/VARI-
ATION FILL-IN, SYNCHRO/ENDING
Accomp volume: 0 to 127 (128 steps)
Free session
Number of patterns: 100 (auto-accompaniment in accordance with selected chord progres-
sion)
Memory function
Songs: 2
Recording tracks: 6 (2 through 6 are melody tracks)
Recording methods: Real-time, step
Memory capacity: Approximately 5,200 notes (total for two songs)
Edit function: Equipped
Demo tunes: 2
Synthesizer function
Parameters: PCM set, amp envelope set, attack rate, release rate, pitch envelope set,
pitch, level, touch sense, pan
Mixer function
Channels: 16
Parameters: Program change number, volume, expression, pan, coarse tuning, fine
tuning, on/off/solo
MIDI: 16 multi-timbre receive, GM Level 1 standard
Other functions
Pitch bend range: 12 semitones upwards and downwards
Transpose: 25 steps (–12 semitones to +12 semitones)
Tuning: Variable (A4 = approximately 440 Hz ±50 cents)
Terminals
MIDI terminals: IN, OUT
Assignable terminal: Standard jack (sustain, sostenuto, soft, rhythm start/stop)
Headphone/Output terminal: Stereo standard jack
Output Impedance: 120 Ω
Output Voltage: 4.5 V (RMS) MAX
Power supply terminal: 9 V DC
Power supply: Dual power supply system
Batteries: 6 D-size batteries
Battery life: Approximately 5 hours continuous operation on manganese batteries
AC adaptor: AD-5
Auto power off: Turns power off approximately six minutes after last key operation. En-
abled under battery power only, can be disabled manually.
Speaker output: 2.5 W + 2.5 W
Power consumption: 9 V --- 7.7 W
Dimensions (HWD): 96.0 ×37.6 ×15.2 cm (37 13/16 ×14 13/16 ×5 15/16 inches)
Weight: Approximately 5.5 kg (12.1 lbs) (without batteries)

— 2 —
ELECTRICAL
Current drain with 9 V DC:
No sound output 412 mA ±20 %
Maximum volume 1165 mA ±20 %
with 12 keys from C3 to B3 pressed in Square wave tone
Volume: maximum, Touch response: maximum
Reverb: Hall
Phone output level (Vrms with 32 Ωload each channel): L-ch 615 mV ±20 %
with key A5 pressed in Bassoon tone R-ch 555 mV ±20 %
Volume: maximum, Touch response: maximum
Reverb: Hall
Speaker output level (Vrms with 4 Ωload each channel): L-ch 2780 mV ±20 %
with key A5 pressed in Bassoon tone R-ch 2570 mV ±20 %
Volume: maximum, Touch response: maximum
Reverb: Hall
Output level (Vrms with 47k Ωload each channel): L-ch 3070 mV ±20 %
with key A5 pressed in Bassoon tone R-ch 2750 mV ±20 %
Volume: maximum, Touch response: maximum
Reverb: Hall
Minimum operating voltage: 6.3 V
About General MIDI
General MIDI standardizes MIDI data for all sound source types, regardless of manufacturer. General MIDI
specifies such factors as tone numbering, drum sounds, and available MIDI channels for all sound sources.
This standard makes it possible for all MIDI equipment to reproduce the same nuances when playing
General MIDI data, regardless of the manufacturer of the sound source.
This keyboard supports General MIDI, so it can be used to play commercially available pre-recorded
General MIDI data and General MIDI data send to it from a personal computer.

— 3 —
BLOCK DIAGRAM
KC0 ~ KC7
FI0 ~ FI9
SI0 ~ SI9
KI0 ~ KI2
PB0 ~ PB3
P10, P13
P14, P17
Working Storage
RAM (256K-bit)
LSI4
TC55257DFL-70L(EL)
MIDI
EA0 ~
EA14
EIO0 ~
EIO7
Sound Source ROM
(24M-bit)
LSI3
LH536PY8
WCKO
SO
BCK
D/A Converter
IC1
UPD6379GR
Filter
Q308 ~ Q311
Main
Volume
Power Amplifier
IC301
TA8248K
Keyboard
MA0 ~ MA19
Effect RAM
(256K-bit)
LSI5
TC55257DFL-
70L(EL)
MD0
~
MD7
Speakers
Output
MA0
~
MA14
MA0, MA1 LRCK, SO
BCK, SINK
LCD
LCD Driver
LSI501
SED1278F2A
SEG1 ~ SEG40
INOUT
Reset IC
IC2
RN5VD40AA
RESET
COM1 ~ COM16
DSP
LSI2
HG51B277FB-1
MD0 ~ MD15 CPU
LSI1
GT913F(T)
Buttons
Assingnable Jack
PB4
VDD Power Switch
NMI
FI10
P23
PA0 ~ PA5
PB0 ~ PB3

— 4 —
KC0 KC1 KC2 KC3 KC4 KC5 KC6 KC7
FI10 Chord 3 Chord 1 ▼9 6 + Tone
KI0 Chord 4 Chord 2 Start/ 8 3 — Rhythm
Stop
KI1 Chord 5 Intro Tempo 72 0
Normal/
▼Fill-In
KI2 Chord 6 Synchro/ Tempo 45 1
Variation/
Ending ▲Fill-In
KC0 KC1 KC2 KC3 KC4 KC 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) #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) C6# (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)
CIRCUIT DESCRIPTION
KEY MATRIX
BUTTON MATRIX
PA0 PA1 PA2 PA3
PB0 Full Range Reverb Mixer Step
Chord
PB1 Fingered Synth Memory Accomp
Volume
PB2 Casio Chord Demo Free Session Split
PB3 Normal Transpose/ Layer Touch
Tune/Midi Response
▼
▼

— 5 —
Reset IC
IC2
RN5VD40AA
DSP
LSI2
HG51B277FB-1
VDD
Reset signal
To power supply circuit
VDD Battery set
RESET
VDD
POWER
From power switch NMI
APO
PLE
CPU
LSI1
GT913F(T)
SCKO
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 B6A6G6F6E6D6 C7
C#3A#2G#2
F#2D#2
C#2 A#6 G#6F#6D#6
C#6
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 five 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. The CPU sends APO
signal to the power supply circuit, also sends a reset signal to the DSP.
Name Voltage For operation of
VDD +5 V CPU, Reset IC, DSP, Sound source ROM, Working storage RAM, Effect RAM
DVDD +5 V LCD driver, Power jack, Sustain jack, MIDI jack
AVDD +5 V DAC, Filter
LVDD +5.6 V LCD dirver
VCC +9 V Power amplifier, Pilot lamp

— 6 —
CPU (LSI1: GT913F-(T))
The 16-bit CPU contains a 1k-byte RAM, three 8-bit I/O ports, two timers, a key controller and serial interfaces.
The CPU detects key velocity by counting the time between first-key input signal FI and second-key SI from
the keyboard. The CPU reads sound data and velocity data from the sound source ROM in accordance with
the selected tone; the CPU can read rhythm data simultaneously when a rhythm pattern is selected. Then the
CPU provides 16-bit serial sound data to the DSP. The CPU also controls MIDI input/output and stores
sequencer data into the working storage RAM.
The following table shows the pin functions of LSI1.
Pin No. Terminal In/Out Function
1 TXD0 Out MIDI signal output
2 RXD0 In MIDI signal input
3 SCK0 Out APO (Auto Power Off) signal output
4, 5 TXD1, RXD2 In/Out Data bus for the LCD driver
6 SCK1 Out 1 MHZ synchronizing pulse output
7 AVCC In DVDD (+5 V) source
8 AN0 In AC adaptor detection terminal.
+5 V when the keyboard is powered by batteries and becomes
0 V to cancel the APO function when AC adaptor is connected.
9 AN1 — Not used. Connected to ground.
10 AGND In Ground (0 V) source
11 BCK Out Bit clock output
12 SO Out Serial sound data output
13 LRCK Out Word clock output
14 GND In Ground (0 V) source
15, 16 XLT0, XLT1 In/Out 20 MHz clock input/output
17 VCC In +5 V source
18, 19 MD0, MD1 In Mode selection terminal
20 RSTB In Reset signal input
21 NMI In Power ON signal input
22 INT/P10 In/Out Data bus for the LCD driver
23 ~ 30 FI0 ~ FI3 In Terminal for key input signal
SI0 ~ SI3
31 ~ 38 KC0 ~ KC7 Out Terminal for key scan signal
39 ~ 46 FI4 ~ FI7 In Terminal for key input signal
SI4 ~ SI7
47 ~ 50 FI8, FI9 — Not used
SI8, SI9
51 FI10 In Terminal for button input signal
52 SI10/P23 Out Chip enable signal for the LCD driver
53 ~ 55 KI0 ~ KI2 In Terminal for button input signal
56 MWNB Out Write enable signal for the DSP
57 ~ 76 MA0 ~ MA17 Out Address bus
77 MCSB0 Out Chip enable signal output for the sound source ROM
78 MCSB1 Out Not used
79 MCSB2 Out Chip enable signal output for the DSP

— 7 —
DIGITAL SIGNAL PROCESSOR (LSI2: HG51B227FB-1)
The DSP receives 16-bit serial sound data output from the CPU and adds the selected effect to the sound data
using the effect RAM. Then the DSP provides the sound data to the DAC. The DSP also controls button input/
output.
The following table shows the pin functions of LSI2.
Pin No. Terminal In/Out Function
80 VCC In +5 V source
81 GND In Ground (0 V) source
82 MRDB Out Read enable signal output for the sound source ROM
83 ~ 98 MD0 ~ MD15 In/Out Data bus
99 PLE Out Reset signal output for the DSP
100 P17 In/Out Data bus for the LCD driver
Pin No. Terminal In/Out Function
1 ~ 3, 80 PB0 ~ PB3 In Button input terminals
4 PB4 In ASSIGNABLE Jack input
5 SO Out Serial sound data output for the DAC
6 WCKO Out Word clock output for the DAC
7 VDD3 In +5 V source
8 TEST — Not used
9 RESB In Reset signal input
10 VSS2 In Ground (0 V) source
11, 12 XIN, XOUT In/Out 20 MHz clock input/output
13 WCKI In Word clock input from the CPU
14 SI In Serial sound data input from the CPU
15 BCKI In Bit clock input from the CPU
16 SINC In 1 MHz synchronizing pulse input
17 VDD2 In +5 V source
18 ~ 25 IO0 ~ IO7 In/Out Data bus
26 RCEB Out Chip enable signal output for the working storage RAM
27 VSS3 In Ground (0 V) source
28 AD1 In Address bus
29 OEB Out Output enable signal for working storage RAM
30 WEB In Write enable signal
31 VDD3 In +5 V source
32 CE2 In Chip enable signal input. High active.
33 AD0 In Address bus
34 CE1B In Chip enable signal input. Low active.
35 ~ 41, 43 EIO0 ~ EIO7 In/Out Data bus for the effect RAM

— 8 —
LCD DRIVER (LSI501: SED1278F2A)
The LCD driver can drive a dot matrix LCD having 40 segment and 16 common lines. The LSI contains 240
graphic symbols in the built-in character generator ROM, and stores 80 characters in the built-in display data
RAM. In accordance with command from the CPU, the LSI is capable of displaying up to 16 characters
simultaneously. The following table shows the pin functions of LSI 501.
Pin No. Terminal In/Out Function
42 , 44, 46 ~ 48, EA0 ~ EA12 Out Address bus for the effect RAM
51 ~ 59, 61
45 ECEB Out Chip enable signal output for the effect RAM
49 EOEB Out Read enable signal output for the effect RAM
50 VSS3 In Ground (0 V) source
60 EWEB Out Write enable signal output for the effect RAM
62, 66, 70, 74, 78 VSS2 In Ground source
63, 67, 71, 75, 79 VDD2 In +5 V source
64, 65, 68, 69, PA0 ~ PA5 Out Button scan signal output
72, 73
76, 77 PA6/7 Out Not used
Pin No. Terminal In/Out Function
1 ~ 22, SEG1 ~ SEG40 Out Segment signal output
63 ~ 80
23 VSS — GND (0 V) source
24, 25 OSC1, OSC2 In/Out Terminals for the built-in clock pulse generator. The external
resistor connected determines the oscillation frequency.
26 ~ 30 V1 ~ V5 In LCD drive voltage input.
Those voltages are used for generating the stepped pulse of
the LCD drive signals.
31, 32 LP, XCLS — Not used
33 VDD In DVDD (+5 V) source
34, 35 FR, DO — Not used
36 RS In Data/command determination terminal.
High: data, Low: command
37 R/W In Read/write terminal. High: read, Low: write
38 E In Chip enable signal.
High: enable, the writing is done at fall edge.
Low: disenable
39 ~ 42 DB0 ~ DB3 — Not used. Connected to GND (0 V)
43 ~ 46 DB4 ~ DB7 In/Out Data bus
47 ~ 62 COM1 ~ COM16 Out Common signal/output

— 9 —
680‰
50V22
C341
Q309
R340
1.5K
AVDD
AG
AGAG
50V22
Q308
C340
C123H
C346
R342 R343 R344
3.3K 4.7K 1K
6.3V220
2SC1740STPR
2SC1740STPR
R341
C345
C821BA
C339
1.5K
R335
C123H
C343 Q310
Q311
3.3K 4.7K 1K
R337 R338
C349
50V22
C350
50V22
R336
AG
AG AG
AVDD
2SC1740STPR
2SC1740STPR
1K
22K
22K
10K 3.9K
1K
R339
R346
R348R349
C348
10V100
R347
R345
C342
C821BA
R334
680‰
From DAC
To main volume
Synch signal
Data
Word clock
Bit clock
Data
Word clock
Bit clock
DSP
LSI2
HG51B277FB
DAC
IC1
UPD6379GR
CPU
LSI1
GT913F(T)
L OUT
R OUT
SI
LRCK
CLK
SO
WCKO
SCK1
SO
LRCK
BCK
SINC
SI
WCKI
BCKI
FILTER BLOCK
Since the sound signals from the DAC are stepped waveforms, the filter block is added to smooth the
waveforms.
DAC (IC1: UPD6379GR)
The DAC receives 16-bit serial data output from the DSP. The data contains digital sound data of the
melody, chord, bass, and percussion for the right and left channels. The DAC converts the data into
analog waveforms and output them to each channel separately.

— 10 —
POWER AMPLIFIER (IC301: TA8248K)
The power amplifier is a two-channel amplifier with standby switch.
The following table shows the pin function of IC301.
Pin No. Terminal In/Out Function
1 NC — Not used
2 B.S.2 — Terminal for a bootstrap capacitor
3 OUT2 Out Channel 2 output
4 VCC In +9 V source
5 OUT1 Out Channel 1 output
6 B.S.1 — Terminal for a bootstrap capacitor
7 Power GND In Ground (0 V) source
8 Stand by In Power control signal input. 0 V: Off, +9 V: On
9 DC — Terminal for a decoupling capacitor
10 NF1 In Negative feedback input
11 IN1 In Channel 1 input
12 IN2 In Channel 2 input
13 NF2 In Negative feedback input
14, 15 Pre GND In Ground (0 V) source

— 11 —
ADJUSTMENT
DISPLAY PCB
1) Items to be adjusted:
2) Adjustment and Test Point Locations (TOP VIEW)
Item Measuring Instrument
Vop voltage setting Voltmeter
(BOTTOM VIEW)
VR501
TP2
TP1

— 12 —
3) Equipment connection/Procedure
Vop voltage setting
Output
Set Voltmeter
TP1-TP2
Input
Connection Input
Point Input Signal Adjust Output
Connection Output Point Adjust for
VR501 Voltmeter TP1-TP2 Adjust for 4.2 to 4.3 V read-
ing on voltmeter under the
temparature 20 to 25 °C.
Makefineadjustmentaccord-
ing to the following instruc-
tion.
1Watching the LCD at 32.52°angle to the horizontal, adjust Vop
voltage so that unenergized segments are seen dimly.
2Watching the LCD at 62.23°(upper limit) angle, check to see the
segments completely.
32.52°
62.23°
LCD
Eye
Eye
(upper limit)

— 13 —
MAJOR WAVEFORMS
1NMI signal
JD connector pin 1
2APO signal
JH connector pin 6
5Key scan signal KC0
JA connector pin 9
6Key scan signal KC1
JA connector pin 10
3Button scan signal PA0
JD connector pin 9
4Button scan signal PA1
JD connector pin 8
9DAC output (L-ch)
JH connector pin 9
0DAC output (R-ch)
JH connector pin 8
ASound signal (L-ch)
JK connector pin 4
BSound signal (R-ch)
JK connector pin 5
7RS signal PA4
JJ connector pin 4
8R/W signal PA5
JJ connector pin 5
1
2
CH1
CH2
3
4
CH1
CH2
5
6
CH1
CH2
7
8
CH1
CH2
9
0
CH1
CH2
A
B
CH1
CH2
0.5 s 20 ms
50 µs0.5 s
1 ms 1 ms
CH1: 5 V
–CH2: 5 V –CH1: 5 V –CH2: 5 V
–
CH1: 5 V
–CH2: 5 V
–CH1: 5 V –CH2: 5 V
–
CH1: 50 mV
˜CH2: 50 mV ˜CH1: 50 mV ˜CH2: 50 mV ˜
Power button ON
Power ON

— 14 —
PRINTED CIRCUIT BOARDS
Main PCB JCM454-MA1M
Top View
Bottom View
2
10
93
8
1
4
7
56

— 15 —
Sub PCB KDM454-MA2M
12 11

— 16 —
LCD PCB JCM454-LCD1M-A
Top View
Bottom View

— 17 —
SCHEMATIC DIAGRAMS
Main PCB JCM454-MA1M
2
10
66
3
4
1
5 6
9

— 18 —
Sub PCB KDM454-MA2M
12 11