Korg MONOPOLY POLYSIX MS-20 User manual

MONOPHONIC
SYNTHESIZER
SERVICE MANUAL
MS-20
.
SPECIFICATIONS
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2.
STRUCTURAL
DIAGRAM...
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3.
CIRCUIT
DIAGRAM
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CIRCUIT
DIAGRAM
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4. FRONT
VIEW
OF PRINTED
CIRCUIT
BOARD
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5. PARTS LIST (Mechanical parts notlisted)........... &
6.
BLOCK
DIAGRAM
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7.
ADJUSTMENT
PROCEDURE
........
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10
KEIO
ELECTRONIC
LABORATORY
CORPORATION
TAaxYO/ JAPAN

1.
SPECIFICATIONS
< CONTROL SECTION >
1.
é.
Keyboard
Voltage
controtled
oscillator t
VC.0.2
V.C.0.
master
control
.
V.C.0.
mixer
, Voltage controlled
high pass filter
. Voltage controlled
low pass filter
. Envelope
generator 1
. Envelope
generator 2
. Modulation
generator
.
Manual
controller
.
P.
Switch
and
volume
. Indicator
"C~C 37 keys (3 octaves)
*Scale (32', 16°, 8 43 (6
octaves,
+
cent,
—
cent)
*Wave form (A, &, PW (TU
~ ILJ), white noise) (4 modes)
*Pulse width adjust 1:1 ~ 1:
* Scale (16', 8", 4’, 2°} (6 octaves,
+ cent, - cent)
*Wave form (M,C, fl, ring
modulator) (4 mcdes}
*Pitch (+1 OCTAVES)
* Master tune (+100 cent}
*Portamento (max. 00 sec)
*Frequency
modulation
intensity
by
MG/T.
EXT
(+5V)
*Frequency modulation intensity
by EG1/EXT (+54)
*V.C.0.-1 level
*V.C.0.-2
level
* Cutoff frequency
(50Hz ~ +5,000Hz)
* Peak (flat~self OSC)
* Cutotf frequency modulation in-
tensity by MG/T.EXT
(-5¥ ~ +5V}
* Cutoff frequency modulation in-
tensity by EG2/EXT
(-5V ~ +5V}
* Cutoff frequency
(50Hz~ 15,000Hz)
*Peak (flat~seif OSC)
* Cutoff frequency modulation in-
tensity
by
MG/T.EXT
(-5V ~ +5V}
*Cutotf frequency modulation in-
tensity
by
EG2/EXT
(+5V~ +5V)
* Delay time (10 sec)
*
Attack
time
(10
sec}
*
Release
time
(10
sec)
* Hold time (20 sec)
*
Attack
time
(10
sac)
*
Decay
time
(10
sec)
"Sustain level (Q~5¥}
" Release time (10 sec)
*Wave form( K~ A ~ 71,
m~ fh ~ ul)
*
Frequency
(1:
1
~
1:80)
*Control
wheet
(center
(O.tH2
~
20Hz}
*Momentary
switch
“tenn
*Volume
cli¢k}
*LED (KBD trigger, MG rate}
< EXTERNAL SIGNAL PROCESSOR >
1. Control section
2. Input and output
3. Indicator {LED}
< PATCH PANEL >
Ly Keyboard
VCF
.
VCO
+
VCF
VCA
EG
*|Input
signal
levei
(dB
max.)
*Low
cut
frequency
(50
~ 2,500Hz)
*High
cut
frequency
(100
~ 5,000HZz}
*CV
adjust
* Threshold
ievel
* Signal
In (auto
pad
system)
(3.0
~+14.0V)
* Amplifier
Out
“Band
pass
filtered
Out
*CV
Out
(Fo
¥)
(0
~
+8.4¥)
*ENV
Out
(0 ~
+5¥V}
*Trig
Out
(+5V
“tonp}
*Peak
indicator
* Trigger
indicator
* Keyboard control voltage output
(exponential) (Q~ +8V)
*Keyboard trigger output
{+5 ~tenp)
*V¥CO-1 + VCO-2 control
voltage input (linear response)
(O~ + 8V)
®VCO-2 control voltage
(linear
response}
(0
~
BV)
*V¥CO-1 + VCOQO-2 external
frequency
control
input
(OCT) (4 5V —5V}
“External signal input
(3Vp-p max.)
*External
HP
filter
frequency
control
input
(2O0CT/V)
(-5V
~
+5V)
*External LP fitter cutoff
frequency control input
{2OCT/V) (—-5SV~ + 5V)
*Total externa! modulation input
(T. ext) (-5~ +64)
* External initial gain control input
(O~ + 5¥)
"EG 1 envelope signal normai
output
(
-5V
=7—7=0V)
*EG 1 envelope signal reverse
output
(+
SVL.
OV)
"EG 7 + EG 2 trigger input
(“tGno}
*EG 1 trigger input (“Leno }
*EG 2 envelope signal reverse
output
(4,-7.0)
* Triangié output (Mi~ A ~ 1)
(SVp-p-Px- OV)
*Rectangle
output
(I~
Tu
~
ingut
cutott
(UT

8.
Noise
generator
=
*
Pink
noise
output
(5Vp-p
+20)
12.
Signal
out
*Signal
output
(2Vp-p
output
in-
*
While
noise
output
(SVp-p
+20)
pedance
3.5kn}
9.
Sample
and
hold
=
*
Clock
trigger
input
(“+
gnp}
13.
Head
phones
*Head
phones
output
((i)
*Sample
signat
input
(5Vp-p
120m
watts
§.6)
max.)
14,
Power
consumption
10
watts
*S/H
output
(5Vp-p
max.)
15.
Dimensions
*569(W)
x
308{D)
x
249(H}
mm
10.
Modulation
VCA
=
*
Control
voltage
input
(0~
+
5V)
16.
Weight
"7.7
kgs
*
Signal
input
(-5V~
+5V)
17.
Accessories
*Patch
cord,
connection
cord
*
Signal
output
(-—5V~
+5V)
(35
emx2,3mx
1)
11.
Manual
controller
*Control
wheel
output
18,
Options
*Stand,
nard
case,
foot
pedal
{-5V
+
OV—
+5V)
(MS-01)
"Momentary
switch
output
*
Junction
box
(MS-02)
(tno)
C
2.
STRUCTURAL
DIAGRAM
Side
panel
(ret)
a
Rotary
knob
{iarge)
ay Rotary knoo (amait)
From
panet
Power supply “! “FI fe
+ _Vaaslormer i c
C.onrol whee:
Main
chassis
Aubber
tee
#5
PE
eae
Ou

3.
CIRCUIT
DIAGRAM
(1)
15 -180506
(SM ~1-02)
&
raeol
rte
Ras
R30
vRIO
925
B80L
2uA
K3CAIGAD
5,
3140
100K18
101%
SELecter
!
)
Le
{FROM EG-2] |
.
Dearere
tees,
Ya20
OOK
‘e
C) fF ROM TEXT,
(i) 6945 SELECTED
*F
covcce
OPER
TLoez
(REVERSE OUT|
+8¥
"NSS
veasse
Rez
am

CIRCUIT DIAGRAM (2)
KLM-128
A ea
az
KLM-129
[516
LEVEL
J
+18
-198v

4.
FRONT
VIEW
OF
PRINTED
CIRCUIT
BOARD
KLM-127
POWER SUPPLY EG 2
MIXER
HP-FILTER
LP-FILTER
|
VCA
Ras
OMe?
(/FRE@ MOD
EGI/ ExT
KBD FOLLOWER FREQ TRIG DETECTOR
‘>
|
“~

KLM-128C
Woiyyanz)
asion

PARTS LIST
(Mechanical
parts
not
listed)
@
CARBON
RESISTORS
not
listed
@METAL
FILM
RESISTORS
1/4Wi%
1000
x
2
1/4W
1%
4039
18
1/4W
1%
4279
22
1/4W 1% 1kQ
1/4W
1%
2kQ
1 /4W 1% 2.94k0
1/4W 1% 4.27k9
1/4W 1% 10ka
1/4W 1% T5ka
T/4aW 1% 20k2
1/4W
1%
61.9k2
1/4W 1% 100ka
1/4W 1% 1102
1/4W
1%
5.11kQ
x x x MK KM uM WK MK RK KH KK
@SOLIO AESISTOAS
1/4W10%
10M
x
7
@ MYLAR CAPACITORS
not
listed
@STYAOL CAPACITORS
50V-12000pF x 1
@ CERAMIC CAPACITORS
5OV-56pF x 1
50V-22pF
x
1
50V-100pF x 5
50V-220pF x 2
S0V-47pF x 1
25V-100000pF x 2
@ TANTALUM CAPACITORS
16V-3.3uF
x
1
16V-6.8nF x 2
@ ELECTROLYTIC CAPACITORS
16V-10uF x 42
16V-39uF x 2
16V-100uF x 4
SOV-ipF
ox)
6
25V-470~F x 1
25¥-10000uF x 1
16V-220uF x 1
@POLYSTYRENE CAPACITORS
50V-3000pF
x
+t
50V-6200pF
x
1
@POLYPROPPYLENE
CAPACITORS
200V-0.22uF
x
7
@TRANSISTORS
2SA-564(S)
x
4
28C-945(L)K
x
1
(special
selected}
28C-1688G
x
2
285C-1685SS
x
13
2SC-644R
x
1
2SK-30(0) x 4
2SK-30(GR) x 4
@DIODES
18-1555 x 33
@.éED
GD4-203RD
x
4
@PHOTOCOUPLER
HTV-P873-G35-201B
x
1
@Ic
wPC-4558C
x
#17
O81
x
5
TL-(97
1)
{3140)
O82
x
1
TL-(O072)
(3140)
MC-14007
x
2
MC-14069B
x
2
wPO4011C
x
1
uPC339C
x
1
#PCi4915
=
x
1
wATIM15
x
1
KORG35
x
2
@SEMI-FIXED RESISTORS
SRISR(10kKB) x 6
SRISR(IGOkKB)
x
7
@ROTARY VARIABLE
RESISTORS
JOKB x 4
100KA
100KA
IMB
2MA
1MA
Printed 10KA
Printed
10KB
Printed 1MB
Printed
4-ganged
100KC
249
10KB
Center click-stop 10KB aan nen aun hry bo x xX KX KM MH KH KM MM KR OM
@ROTARY SWITCH
SRM-1034
1-15mm
x
4
@KEYBOARD
ESK-431
37
key
@TERMINAL
LUG
BOARD
2L4P
x
1
@PUSH
SWITCH
MS-102
x
1
@CONNECTORS
TW3P
x
6
4P x 2
SP x 2
7P x 1
BP x 2
SP x 3
SP
x
1
Femaie
Connectors
3P
x
10
4P x 2
SP x 3
7P x 2
BP x 2

7.
ADJUSTMENT
PROCEDURE
7-1 Power supply check
1.
Positive
rippie,
Should
be
no
more
than
2mVp-p.
Set
oscilloscope
vertical
gain
at
10mV/em
and
check
that
power
supply
ripple
is
2m
or
jess.
Negative
ripple.
Same
as
positive,
should
be
na
more
than
2mVp-p.
7-2.
Pitch
adjustment
1. ¥CO-1.
Perform
adjustment
with
synthesizer
controls
at
“normal
setting’
(Scale=8,
Waveform=
Tu
,
Master
Tune,
Pitch,
and
ail
cther
knobs
at
“0").
See
figure
1.
a.
Play
C-4
(high
C)
on
the
keyboard
and
ad-
just
the
high
@
semi-fixed
screw
until
you
obtain
the
correct
tuning
as
indicated
by
WT-10A
{connected
to
the
SIG
OUT
jack).
b.
Play
key
C-1
and
adjust
the
low
@
semi-
fixed
screw.
c.
Repeat
steps
a
and
b
as
many
times
as
necessary
until
both
are
tuned
to
the
correct
pitch.
d.
Check
the
tuning
of
C-1,
C-2,
C-3,
and
C-4
on
the
WT-10A
meter
to
make
sure
pitch
devia-
tion
is within
+2
cents
for
each.
10
e.
Change
the
scale
to
32’,
16',
8’,
and
4'
and
check
the tuning
of all four
¢ keys
to make
sure
that
the
pitch
deviation
of
each
is
within
+10
cents.
2. ¥VCOQ-2.
Set
the
VCO-1
level
at
“O"
and
the
VCO-2
level
at
"10".
Then
follow
the
same
procedure
as
for
VCOQ-1,
by
adjusting
the
hign
@
and
low
@
semi-fixed
screws.
7-3. KBD CV adjustment
Use
a
4-1/2
digital
voltmeter
to
measure
the
KBD
CV OUT signal.
a.
Measure
output
voliage
first
when
you
play
key
C-4,
then
when
you
play
key
C-3.
The
output
voltage
for
C-3
shoud
be
exactly
half
that
for
C-4.
Adjust
the
KBD
CV
high
@
semi-fixed
screw
as
necessary
so
that
C-3
produces
half
the voltage of C-4.
ob.
Measure
C-2 and
then
C-1
in
the
same
way.
Adjust
the
KBD
CV
low
@
semi-tixed
screw
as
necessary
so
that
C-2
produces
exactly
half
the
voltage of C-4.
c.
Repeat
steps
a
and
b
as
many
times
as
necessary
until
the
output
voltage
of
each
of
C-1,
G-2,
C-3,
and
C-4
is
exactly
half
that
of
the
next.
DIGITAL
VOLTMETER

7-4. VCF Fe adjustment
Connect a frequency counter to the PHONES jack
(since a high output level is needed for measure-
ment). Set VCO-1 and ¥VCO-2 level at"0”.
1.
VC
HPF
Refer to the settings shown in figure 2. Set the
LPF
PEAK
knob
at
“0”,
and
the
HPF
PEAK
knob
OOOO
SIG LEVER Loweu) mp cut Ce Ds TWRER LEVEL
Fig. 2
1
at "10". Then adjust the @ semi-fixed screw as
necessary
so
that
the
HPF
oscillation
frequency
is 500Hz.
. VOLPF
Set HPF PEAK at “0”, and LPF PEAK at “10”.
Then adjust the @ semi-fixed screw in the same
way as you did for the HPF.
FREQUENCY
COUNTER
£5) Sf PAOCESSDA
:
Oe POLE }O pi 0-0