Yamaha JOGR JOGRR CS50 User manual

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CONTENTS
Introduction
Function
of
Panel Lever
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(I) Panel 1 ·········································································································································· 2
(II) Panel 2 ·········································································································································· 5
(III)
Panel 3
·········································································································································· 6
(IV) Rear Panel .................................................................................................................................... 7
(V) Others
·····························································f············································································
7
CS-50 Circuit Board Contents ··································/·············································································· 8
Basic Block
Diagr3ID
of
CS
······················································.................................································· 9
Keyboard ................................................................................................................................................ 10
Key
Data
Producing (Encoding) Circuit
11
Key DataProducing Circuit .......·····...............................................···················································
11
PIN Terminal Description
of
LSI (YM26600) .................................................................................... 12
Reference
Timing Clock
(rp,
SC, SC8)
Data
Processing Based
on
Time-sharing
Control
of
Produced Notes
13
13
13
13
Operational Principle of·KEY
Data
Producing Circuit ......................................................................
13
KEY Coder ............................................................................................................................. 14
Output
Timing Chart for KEY Coder ..................................................................................... 16
KEY Assigner ···································································································································· 16
KEY Voltage Detecting Circuit ··············································································································· 20
Basic Construction
of
KEY Voltage Detecting Circuit ····································································· 20
PIN
terminal
Description
of
LSI (YM26700) ···················································································· 20
Timing Clock
(rp,
SC, SC8) ·····················································································································
21
Operational Principle
I
of
KEY Voltage Detecting Circuit ·
··
······
··
········........
··
··
··
··
······
·· ···· ··
........· 22
D-A Converter ···································································································································· 23
Operational Principle
II
of
KEY Voltage Detecting Circuit ······························································· 24
Port3IDento Operation ···································.····················································································· 24
Operational Principle
lli
of
KEY Voltage Detecting Circuit ····························································
25
Voltage-Controlled Oscillator
Basic Construction
of
Sound Source Circuit
27
27
PIN Terminal Description
of
VCOIII (IG00153) ................................................................................. 27
Operational Principle
ofVCO
III (IG00153) 28
Outline
of
VCO
III
Circuit Operation ································································································ 29
Transposition Circuit
...
........................................................................................................................... 30
Wave
Shaper Converter Circuit (WSC) ································································································ 31
Noise Source Circuit ..............................................................................................................................
32

Voltage Controlled Filter ..............................................................................................................................
Basic Construction
of Voltage Controlled Filter
Operational Principle
of LSI (IGOO 156) ................................................................................................
Outline
ofVCF Circuit Operation
Voltage Controlled Amplifier Circuit
Basic Construction
of VCA Circuit
Operational Principle
of LSI (IG00151)
Outline
ofVCA Circuit Operation .................•.......................................................................................
Envelope Generator
Basic Construction
of Envelope Generator ········· ···· ····· ················ ·························.·······.......................
Operational Principle
of LSI (IG00159) ...............................................................................................
Outline
of VCA-EG Operation ···············································································································
Outline ofVCF-EG Operation ...............................................................................................................
Expression Circuit
Output Amplifier and Headphone Amplifier
Modulator Circuit
I.
PWM Oscillator Circuit
2. Ring Modulator
3. Sub-oscillator and Touch Response
Control Voltage Mixing Circuit ············································......................................................................
1. VCO Vibrato Control Voltage Mixing Circuit
2. VCF Cut-OFF Frequency (fc) Control Voltage Mixing Circuit
3. VCF Resonance (Q) Control Voltage Mixing Circuit
4. VCA Control Voltage Mixing Circuit
Other Circuits
I. Sustain Control Circuit
2. Tuning Voltage Circuit
3. Preset Tone Setting Voltage Divider Circuit ....................................................................................
Tuning Method!
33
33
33
34
39
39
40
40
42
42
43
44
45
46
48
49
49
50 I
54
,,II
;
.: __ \~
59
59
59
59
60
61
61
62
63
65

Panell (PN 1)
Pane12 (PN 2)
PITCH
iQ%
Pane13 (PN 3)
r-----· RING MODULATIOR-----,
ATTACK DECAY
TIME TIME
DEPTH
Ill
PORTA-
SUSTAIN MENTO
MODULA
SPEED
-TION
rr
1
I II GLISS-
[IJ [I lANDO
N~liiiiiG~C
SLOW 0 0 0 SHORT SHORT
FU:-iC
SPEED VCO VCF VCA PORTAMENTO
-TIO:'J
SUSTAIN GLISSANDO
PANEL CONSTRUCTION OF CS-50
LOW
0©©~©
LEVEl IN FOOT Hlr.H
CONTROL LEH
l.. EXT .J '--OUTPUT_)
FAST 1~0 9~% l 10 HIGH HIGH HIGH HIGH -5 +5 LONG LONG LONG 10 10 LONG LONG 10 LONG 10
III~g£ IItititii IIIItti
SLOW 0
50 % 0 LOW LOW LOW LOW 0 0 SHORT SHORT SHORT 0 0 SHORT SHORT 0 SHORT 0
SPEED PWM PW [L ~ NOISE HPF RESH LPF RESL IL AL A D R
VCF 0>J A D S
LEVEL
R LEVEL
~------vco------~
'-------- VCF ------------------'
( TONE
SELECTOR
,--TRANSPOSITION-, r- TOUCH RESPONSE~
RESO BRILL!
NANCE ANCE vco VCF
BRILLIANCE LEVEL
It
Jll<T I ,II OCT I IIr
I VOLUME
STR-
STR- BRASS BRASS f-LUTE
ELEC
CLAVI
HARPS!
GUJ- GUI- fUNKY
FUNKY FUNKY
PANEL
20CT
Q
lNG
lNG -TRIC CHORD
CHORD TAR TAR
PIANO
OOWN
now, r0 R'"'I uj
1 2 1 2 1 2 1 2 3
EXP.
PEDAL
Connected
to
Foot controller
jack
L_ SUB OSC __j
0
HEAD PHONE

PANEL CONSTRl
Panell (PN 1)
10 HIGH HIGH HIG
SLOW 0
50 % 0
SPEED PWM PW iL ~ NOISE HPF RESH LPI
~-------vco------_J
Panel2 (PN 2)
PITCH
Panel3 (PN 3)
r--RINI. MODULATTOR-,
ATTACK DECAY MODULA RESO BRILLT
TIME TfME DEPTH SPEED -TTON NANCE ANCE
IIIII It
PORTA-
SUSTAIN MENTO
I
II GL!SS-
[J:J [ I lANDO
'~1Il!±II"
SLOW 0 0 0 SHORT SHORT
FUc-:C SPEED VCO VCF VCA PORTAMENTO
-TIOCI SUSTAIN GLISSANDO
TONE SELE<
STR- STW BRASS BRASS FLUTE ELEC CLAVI HARPS! Gl
ING lNG -TRIC CHORD CHORD V
PIANO
2

rRUCTION OF CS-50
LOW
0©©~©
LEVEl IN FOOT H!(;H
CONTROl. U·:R
L EXT ...) L. OUTPUT .J
til"t!Ili" IlTI"iiill
OW LOW LOW 0 0 SHORT SHORT SHORT 0 0 SHORT SHORT 0 SHORT 0
ESH LPF RESL IL
AL A D R VCF "'-./ A D S R LEVEL
LEVEL
--~-~ VCF -~~~~------'
'-----------~~ VCA -~~~--'
E SELECTOR------~
HARPS! GUI - GUI- FUNKY FUNKY FUNKY PANEL
J CHORD TAR TAR
2 2 3
,-TRANSPOSITION--,
Connected
to
Foot controller
jack
,.--TOUCH RESPONSE--....
VCO VCF BRILLIANCE LEVEL
rrrr
L_ SUB OSC _.J
VOLUME
0
HEAD PHONE
EXP. PEDAL

e
'

•
INTRODUCTION
The CS series synthesizers are innovative synthesizer products
with a
number of unique features. In order to handle these
products properly, the service engineer must fully understand
not
only the characteristics of each model, but also the principles of
the synthesizer.
This manual contains detailed descriptions
of the construction
and operation
of the various circuits, and the functions of the IC's
used in them, for Model CS-50. Since each
of the circuits employs
digital technologies,
it is essential to understand the fundamentals
of digital technology before reading the manual. In order to
service a CS, thorough mastery of this manual in combination with
the Service Manual
is recommended.

FUNCTION OF PANEL LEVER
• I
FA~T 10 90% ~0 Hrr;H HTCH Hli.H HlGH -5 -'- 5 LONG LONG LONG 10 10 LONr; U)Nr; 10 LONr-; 10
IIi~~! lii!iiiii iiiiiii
SLOW 0 50"~ 0 LOW LOW LOW LOW 0 0 SHORT SHORT SHORT 0 0 SHORT SHORT 0 SHORT 0
SPF:EO PWM PW _n_ f"'-... .'JOTSF.: HPF RF.S1-1 LPI; RESL lL \L A R VCF N A D R LEVEL
LEVEL
~-----vco--____J ~-----------VCF----------J
~--------VCA------_J
(j)
® ®
[I] Panel 1
The controls illustrated above work only when the "PANEL" (green) switch of the Tone Selector switches on
Panel 2
is ON. The Panel 1 controls allow setting of the factors which will produce the sounds one wants and create
closer-to-natural tone color.
G)vco (Voltage Controlled Osc:illatorl
Selects the sound source waveshape best suited for the tone color to be created.
JL ................................ Selects the square wave for the sound source.
~
~
f---100% • I ~0%+
50
%, I
f.a--90%-J?~--90%-1?~-
1Jl31F]f
(Fig. A) Duty ratio of square wave
When the duty ratio (as illustrated at the left), indicates 50%, the
waveshape
is generally called the square wave. The signal includes the
odd-numbered harmonics and
is best for synthesizing tone colors like
those
of the clarinet.
For a waveshape with a larger duty ratio (as illustrated at the left), the
signal also includes the even-numbered harmonics, and
is best for
synthesizing tone colors like those
of the trumpet.
PW (Pulse Width) ................ This lever changes the duty ratio from 50% to 90%, allowing variations in
the harmonic composition of the sound source.
PWM (Pulse Width Modulation)
I 70% 30%
I I
__filJL_J
!"'50%"!<50%~
I· I ·I
40% 40%
Duty ratio (70%) set
by the pw lever
(Fig. B)
This lever rhythmically modulate the pulse width up to ±40% with the
duty ratio set by the
PW lever at the basic reference by an ultra-low
frequency modulation signal.
· SPEED . . . . . . . . . . . . . . . . . . . . . . . . This lever alters the
PWM speed by changing the frequency of the
modulation signal.
~ ..................... This lever selects the saw-tooth wave sllipe for the sound source. This
wave shape contains the high-order harmonics of smaller amplitude than
those
of the square wave and is best for synthesizing tone colors like those
of the violin, although its tone color is not bright.
2---------------------------------------

NOISE . . . . . . . . . . . . . . . . . . . . . . . . This lever selects the white noise which not only simulates the sound
of
wind or
waves
but also synthesizes the breathing noise
of
wind instruments
such
as
the noisy flute, by mixing with the corresponding sound.
"v
(Sine
Wave
shape) . . . . . . . . . . . This sine
wave
shape
is
fed directly into the
VCA
without passing through
tlie VCF.
Over
a period
of
time the sound volume level will change.
®
VCF
(Voltage-Controlled Filter)
In
conventional electronic organs, the cut-off frequency (fc)
ofthe
filter which determines the tone color
is
fixed,
not
variable. In the actual mechanical instruments, however, the tone color varies from moment to moment. More
natural sounds can
be
simulated
by
controlling the voltage envelope with a
VCF
in which the fc
is
shifted by the
change
·in
voltage.
• HPF (High-Pass Filters)
/
..........
This fllter passes
signals
with frequency component above the filter's cut-
off
frequency -and gradually rejects signals with frequency component
below the cut-off point. The higher the lever
is
set, the higher the cut-off
point (fc) will
be
shifted,
giving
more brilliant tone color.
(fc)/
(fc) /
L---+--'--'----t-----__,_f
fcl
fc;2
(Fig. C)
•
RESH
(Resonance High)
High-pass
fJ.lter
Resonance
Amplitude
fc
(Fig. D)
Adding resonance to a high pass filter causes the fllter to emphasize a band
of
frequencies just at the cut-offpoint. Resonance
is
extremely important
in the synthesizer filters. Almost every mechanical instrument has its own
characteristic resonances, and in order
to
simulate close-to-natural sounds,
this lever
is
raised: the higher the lever
is
set, the sharper the band
at
fc
will be emphasized.
• LPF (Low-Pass Filter)
..........
. This fllter rejects signals with frequency component above the fc, in
contrast to the HPF. The higher the lever
is
set, the higher the
fc
will
be
shifted, thereby passing the higher frequency component
of
the signal.
Amplitod•l
I t
-J'.
fc
2
fc,
fc,
(Fig.
E)
• RESL (Resonance Low)
..........
Emphasizes sharply the frequency component at the fc
of
the LPF, in the
same way
as
the RESH.
• Envelope for
VCF
(I
L,
AL,
A, D,
R)
Changes from moment to moment both fc's
of
the high pass filter and the low pass filter with a voltage envelope,
as
illustrated, indicating the change
of
tone color (fc) with respect to time, within the time span from the beginning to
the die-away
of
the sound.
I
---
-+-----"'-
r----
....
: : I
IL
----:----1-
---
-
--
i-
- -
--
,
....
_.....,.
Time
~A'l>!~n~i
k--R___,.:
I
I I
I
I
I
1
KEY-ON
KEY-OFF
(Fig. F)
----------------------------------------------------------------------3

o IL (Initial Level) . . . . . . . . . . . . . . . This sets the starting point of the cut-off frequency (fc) of the VCF at the
moment a key is depressed. The fc rises from this level toward the
sustaining level.
e AL (Attack Level) . . . . . . . . . . . . . Sets the highest level
of the fc for both the VCF-HPF and the VCF-LPF to
rise after a key is depressed. The greater the difference is between the IL
and the AL, tl,e more pronounced the change
of tone color from soft to
brilliant.
e A (Attack Time) . . . . . . . . . . . . . . . Controls the time required to change the
fc from the IL to the AL. For
instance, when A
is long (fc rising slowly), the tone color changes
gradually from soft to brilliant, and the voltage envelope shows a gentle
slope from the IL to the AL.
® D (Decay Time) . . . . . . . . . . . . . . . Controls the time span from the maximum fc at the Attack Level (AL) to
the
fc of constant condition (the key kept depressed: Sustain Level) of
both the fc's of the VCF-HPF and VCF-LPF.
e R (Release Time) . . . . . . . . . . . . . . Controls the time in which the
fc returns from the sustain level toIL from
the moment that the key
is released.
@ VCA (Voltage Controlled Amplifier)
Controls the ampl~tude of the signal. Each mechanical instrument has its own pattern of changes in sound intensity
(loudness) during the rise, sustain and decay phases, and this
is a very important factor in its total characteristic
tone color. For instance, the sound
of a piano rises rapidly when a key is depressed and dies away quickly when it
is released; but if the damper pedal is pressed, the sound will be sustained long after releasing the key. Accordion
sound rises fairly slowly.
In order to simulate the constantly changing volume
of sound from the start to the die-away in the musical
instrument, there are two ways
of controlling the VCA gain: manual control with two levers (VCF and ~), and
envelope control
as same as the VCF.
Envelope for VCA (A, D, S, R)
Sets the time course of changes in loudness from the start to the die-away with the following four parameters:
@ A (Attack Time) ................ Determines the time span of loudness rising from zero to the peak level
when a key
is depressed.
• D (Decay Time)
................ Determines the time span of loudness falling from the peak level to the
sustain level (see 25).
e S (Sustain Level)
............... Sets the loudness level to be sustained while the key is held down.
e R (Release Time, Sustain Time)
.... Controls the time span of loudness falling from the sustain level to zero
when the key
is released.
4~-----------------------------------

[II]
PANEL
2
® ® ®
RJNf;
MODULATOR
TONE
SELECTOR TRANSPOSITION
TOUCH
RESPONSE
1,111111111111
uDJJJ
lrrr
STR PANEl.
VOLUME
0
RESO-
PITCH DEPTH
NANCE
~rry
ATTAW
cr
rS~EDcr
11
'\::::::)
TIME
DECAY
I
MODULA
~
I
TIME
TION
BRILL!
'---t=::__j
ANCE
-P.Jflt
CD
PITCH
Controls the pitch.
The pitch can be changed by plus or minus a half octave from the center click p0int (A3=443
Hz)
with the coarse
knob (outside) and
+
14,
-11
Cent with the trifle control knob (inside).
@ RING
MODULATOR
Provides a kind
of
amplitude modulation (AM), producing a very complex characteristic such
as
nasal sound, which
contains high-frequency components free from the fundamental frequency, emphasizing beating sounds.
• MODULATION
.............
Controls the
1:1ixing
ratio
of
the ring-modulated signal
to
a non-modulated
signal which by-passes the ring modulator, thus varying the depth
of
the
ring modulation effect.
• SPEED
•DEPTH
Sets the speed
of
the modulation signal.
Controls the maximum beat speed controlled by Attack Time Lever and
Decay
Tirp.e
Lever.
• ATTACH TIME
............
Controls the time span
of
the beat speed rising from the speed set by the
SPEED lever to the maximum speed set by the DEPTH lever, when a key
is
depressed.
• DECAY TIME
.............
Controls the time span
of
the speed falling from the maximum speed
to
the constant speed set by the SPEED lever,
as
set by SPEED lever.
Sr><OO
of
FAIST
modulation
signal
SLOW
@ RESONANCE
n...~~--DEPTH
I
I
I
I
I
I
I
I
I
I
I
~I
ATTACK
TIME
KEY-ON
Takes the resonance for the frequency band at the cut-off frequency,
as
in
case
of
RESH
and
RESL
emphasizing.
the sound
of
that frequency and producing a unique sound.
@
BRILLIANCE
When
this lever
is
shifted toward
MAX,
the cut-off frequencies
of
HPF and LPF
rise
to
increase the amplitude of
the higher harmonics, resulting in the more brilliant sound.
When
shifted toward
MIN,
the higher
harmonic~
are
rejected,
giving
softer sound.
-------5

@
TONE SELECTOR
Selects the sound which has been preset to the tone color
of
the particular instrument.
If
none
of
the levers
is
depressed, the sound
is
automatically set to STRING I at the left end.
If
two or more tablet switches are depressed
simultaneously, the lever (tone) farthest
to
the right
is
automatically selected.
While
the preset tone
is
used, the
manual controls on Panel I are inoperative.
@
TRANSPOSITION
A switch lever to shift octave.
• 1
OCT
UP
. . . . . . . . . . . . . . . . . The keyboard scale shifts to C
3
~
C
7
• NORMAL . . . . . . . . . . . . . . . . . The keyboard scale shifts
to
C
2
~
C
6
• 1
OCT
DOWN
..............
The keyboard scale shifts
to
C
1
~
C
5
• 2
OCT
DOWN
. . . . . . . . . . . . . . The keyboard scale shifts to C
0
~
C
4
When
no lever
of
this switch
is
depressed, NORMAL
is
operative.
If
two or more levers are depressed, the lever
farthest
to
the right
is
automatically operative.
(j)
TOUCH
RESPONSE
The following parameters are controlled by the intensity (keyboard depth)
of
keyboard depression.
• LEVEL . . . . . . . . . . . . . . . . . . . The deeper the key
is
depressed, the louder the sound.
• BRILLIANCE . . . . . . . . . . . . . . The deeper the key
is
depressed, the more brilliant the sound.
:
~~~}.
. . . . . . . . . . . . . . . . . . . . The deeper the key
is
depressed, the greater the effect
of
the sub-oscillator.
@
VOLUME
Controls the overall sound volume.
[Ill]
PANEL 3
SUSTAIN
PORTA
GLTSS
I ll
MENTO
ANDO
m m
r---Sub·Oscillator~
FAST
10
10 10
LONG LONG
~~~
IIIII
ili
SUB-OSCILLATOR
CD
FUNCTION
SLOW
0 0 SHORT
SHORT
FUNCTION SPEED
VCO
VCF VCA SUSTAIN
b2~~-l~~TO
1.'
1'
®
rv
®
rv
cv
Selects one
of
the following six
wave
shapes for modulation signal.
'\_;
(Sine
Wave)
Smooth modulation.
r------._
(Sawtooth
Wave)
Modulation with quick
rise
.
.--------J
(Sawtooth
Wave)
Modulation with slow rise.
ILJ
(Square
Wave)
Angular modulation.
NOISE Variable modulation with pink noise.
EXT . . . . . . Modulation signal derived
not
from the sub-oscillator
but
from an external audio signal (such
as
a rhythm box, record, tape, etc.), or an external oscillator other than the CS-50.
@
SPEED
When raised, speed
of
the vibrato, wah-wah and tremolo increases.
6-------------------------------------------------------------------------------

@ vco
Generally called vibrate, VCO produces pitch changes in accordance with voltage. The vibration effect grows deeper
when the lever
is raised.
@ VCF
Generally called wah-wah, VCF changes the cut-off frequency according to voltage. By raising this lever, this effect
becomes deeper.
@ VCA
Generally called electronic tremolo, the sound signal amplitude is changed according to the modulation signal. The
effect grows deeper when the lever
is raised.
@ SUSTAIN i & II SELECTOR SWITCH
When set to SUSTAIN I and several notes are released, each note decays independently. When set to SUSTAIN II,
the decaying note
is replaced by another note, when the key for the latter is depressed.
(j) SUSTAIN LEVER
Controls the decay time from releasing a key to die-away.
@ PORTAMENTO & GLISSANDO SELECTOR SWITCH
The shift from the previously depressed note to the newly depressed note proceeds smoothly in PORTAMENTO,
and in steps in GLISSANDO.
If SUSTAIN II is depressed at the same time and the key is released during the shift,
the interval continues
to change while decaying.
@ PORTAMENTO & GLISSANDO LEVER
Controls the speed at which the interval changes in the portamento or the glissando.
[IV] REAR PANEL
rOUTPUf'"\ r-EXT-....
HIGH CON~~~~ LEl-t IN LEVEL
@~@@Q
LOW
G) OUTPUT
Since the synthesizer includes neither power amplifier nor loudspeaker, the sound becomes audible only when the
signal is fed from this terminal
to an external amplifier and a speaker. The output level is OdBm for HIGH, and
-18dBm for LOW, when all the volume controls are turned fully clockwise and keys for four notes are depressed.
@ FOOT CONTROLLER·
Connects the expression pedal for free volume control.
@ EXT. IN
Input terminal of external signal for one of modulation signal for sub-oscillator effect. The signal level can be
controlled by the level control.
[V] OTHERS
A headphone can be connected for monitoring to the HEADPHONE terminal, located on the bottom of the CS-50.
·-------7

CS-50
CIRCUIT BOARD CONTENTS
-
Circuit board
Main
circuit Other circuits
KAS
Key data producing circuit Master
clock(</>)
oscillator
KEY-ON signal buffer circuit
Delay circuit
Key voltage detecting circuit Key-voltage ladder network circuit
Key-voltage integrator and gate circuit
Key-voltage buffer amplifier
Glissando (or Portamento) operation control circuit
SH
Key-voltage sample hold circit Sustain mode switching circuit
Ml Voltage controlled oscillator (VCO) Transposition switching circuit
Wave,
shaper converter circuit Selection gate circuit
of
sound source wave shape
Voltage controlled ftlter circuit (VCF) Control voltage generator (VCF-EG)
Voltage controlled amplifier circuit (VCA) Control voltage generator (VCA-EG)
------·
M2
to
-do.-
-do.-
M4
PRA Buffer amplifier circuit for MIX use Ring modulator circuit
Expression circut
Output amplifier circuit
Headphone amplifier circuit
SUB
Sub-oscillator,
PWM
oscillator
Level control circuit for modulation signal
of
Sub-oscillator
Buffer amplifier for
touth
response
detected signal.
R7 Mixing circuit for control voltage.
T71,T72 Voltage distributing circuit for pre-set tone use
*DC
supply (
+
IOV).
*Incorporated in T71 sheet
8-------------------------------------------------------------------------

BASIC BLOCK DIAGRAM
OF
CS
(IIJIIKeyboard
I
N
I I
Key Data
Producing
Circuit
Keyboard
Key Data
Producing
Circuit
Key Voltage
Detector
Voltage
Controlled
Oscillator
(VCO)
Voltage
Controlled
Filter (VCF)
Voltage-
Controlled
Amplifier
(VCA)
Function
and Control
Voltage
Circuit
¢::1
Pulse
Key,
Voltage
Detector
~
Sound Signal
Voltage
Controlled
Oscillator
(VCO)
Voltage
Controlled
Filter
(VCF)
Function and Control Voltage Circuit
-Control Voltage
When a
key
is depressed (ON), the
key
data producing circuit
is
activated.
Voltage
Controlled
Amplifier
(VCA)
OUT
The note and the octave for the depressed key are encoded into digital data
of
4 bits and 3 bits, respectively, and
output
up to four notes sequentially
on
a time-sharing basis.
One
of
the key voltages previously set between
0.25
V
DC
and
4 V
DC
is
detected and
is
output
by
opening the gate
on the basis
of
the
digital
data
from
the
key data producing circuit, corresponding to the depressed key.
Generates the sawtooth wave having an interval corresponding
to
the
key voltage from the above-mentioned detec-
tor and provides a square and sine wave as
the
sound source
on
the basis
of
the
sawtooth
by
feeding the latter
into
a
wave shaper converter. The vibrato effect can be obtained
by
adding a manual control·voltage or a modulation
signaJ.Jrom sub-oscillator.
The
tone
color can be varied in terms
of
time span by applying a sawtooth or square wave to
the
VCF.
If
the VCF
is
controlled by the modulation signal
of
the sub-obscillator or
touch
control signal, the wow-wow effect can be
expected.
The time-dependent level changes such as rise and decay, which are characteristic parameters
of
mechanical instru-
ment
sound, can be closely simulated
by
feeding an envelope created
by
manually setting A (attack), D (decay), S
(sustain time) and R (release time) controls in the VCA section
of
Panel I into the VCA,
to
shape the
output
signal
of
the VCF. Applying the alternative voltage through a sub-oscillator or touch control produces
the
tremolo-like
level effect.
Produces, controls and switches the envelope, the manually set
DC
voltage,
or
the alternative voltage from
the
sub-
oscillator or touch control, for controlling VCO, VCF and VCA.
-----------------------------------------------------------------9

KEYBOARD
To octave terminals
U
1
to
U
4
on KAS Circuit board
+-+-+-t-+-+--+-t-+----
+---+--+---4-+-+--+-----
.._-+---1-+-----l----11-------
.._+--+---4-+-------
.._-+---1-+---------
..___+--+-------
+---+-------
CL
C~
D
D~
E F
F"
G
G"
A A" B C
To
note terminals
CL
to C on
KAS
Circuit board
The key-switches on the keyboard are divided into 4 blocks
~rresponding
to each octave.
All_!he
_¥ak~
(M)
c~
tactsofthekeyswitchesin each block are connected
together(~
bar), to form four terminals,U
1,
U2,
U3
and U4,
which are linked to the input terminals of the octave data encoder on the
KAS
(key assigner) circuit board, to
produce the octave data by detecting to what octave the depressed note belongs.
On
the other hand, the transfer
sides
of
the key switches for the
same
note in 4 blocks (e.g. C
2
#, C
3
#, C
4
# and C
5
#) are connected together,
except those
of
C
2•
The lead wires for these 12 notes from C#through Cplus
~at
for the lowest note C
2
which
is
designated
as
CL
are linked to
CL
to C terminals on the
KAS
circuit board to encode what note
is
being depressed.
Thus,
if
a key switch
is
depressed, the particular circuits are closed to encode the octave data (3 bits) and the note
data (4 bits) for that note in the key data producing circuit.
10---------------------------------------------------------------------
\
.

KEY
DATA PRODUCING (ENCODING) CIRCUIT
KEY DATA PRODUCING (ENCODING) CIRCUIT
When
a key
is
depressed, the corresponding octave terminal (one
ofU
1
to
U
4)
and note terminal (one
of
CL,
C#to
C)
are connected, and 3-bits octave data and 4-bits note data are provided (7 bits in all).
In
Model CS-50, up
to
four notes can be sounded simultaneously, and the data for four notes are encoded and output sequentially on a
timt>-sharing
basis. The ON/OFF data signals
of
each key are also detected and produced.
I (
U4
o------1
ll
mu----;
~
6
TB
I
--7
CLo-----1
Master clock oscillator
94KHz±SKHz
U4}
: octave
~
terminals
U1
c
B
note
terminals
Key data producing circuit
LSI: YM26600
N4
I
I
I
Nl
K04
Fig. 2
Basic
Construction
of
Key Data Producing Circuit
To key
Timing } voltage
clock detecting
circuit
The key data producing circuit consists
of
an
IC
(YM
26600) and a master clock oscillator which operates the LSI
(YM
26600)
as
shown in Fig.
1.
-------------------------------------------------------------------11