Moog Minitmoog 300A, Satellite 5330 Owner's Service Manual
MANUAL
NO.
993-041990-002
OWNERS
and
SERVICE
MANUAL
for
nnaoq
MINITMOOG/
SATELLITE
Minitmoog
Model
300A
Satellite
Model
5330
Introduction
The
owners
portion
of
this
manual,
pages 1 through
11,
provides
introductory
material
to
familiarize
the
owner
with
the
features,
specifications
and
initial
set-up
of
the
Minitmoog
Synthesizer,
Model
3Q0A,
and
the
Satellite
Synthesizer,
Model
5330.
The
technical
portion
of
this
manual,
pages
12
through
57,
provides
servicing,,
replacement
parts
list
and
illustrations
to
enable a qualified
technician
to
service
and
maintain
the
Minitmoog
and
Satellite
Synthesizers.
Index
MINITMOOG
SYNTHESIZER
CONTENTS
Controls
Quick-Set
Voice
Tabs
2
Modulation,
Oscillation
and
Touch
Controls
3
Slide
Control
Panel
4
Accessories
and
Connections
10
Care
of
Your
Synthesizer
11
Technical
Sections
12
SATELLITE
SYNTHESIZER
PAGE
CONTENTS
PAGE
Controls
5
Quick-Set
Voice
Tabs
6
Modulation
8
Slide
Control
Panel
9
Accessories
and
Connections
10
Care
of
Your
Synthesizer
11
Technical
Sections
12
THESE
DRAWINGS
AND
SPECIFICATIONS
ARE
THE
PROPERTY
OF
MOOG
MUSIC
INC.
AND
SHALL
NOT
BE
REPRODUCED
OR
COPIED
IN
WHOLE
OR
IN
PART
AS
THE
BASIS
FOR
MANUFACTURE
OR
SALE
OF
THE
ITEMS.
Minitmoog
Controls
SLIDE
CONTROLS
MODULATION
GLIDE
VOLUME
PANEL
CONTROLS
CONTROL CONTROL
SOLO
KEYBOARD
SYNC,
GLIDE
SUSTAIN
TABS
POWER
OFF-ON
SWITCH
INDICATOR
LIGHT
QUICK-SET
VOICING
TABS
FILTER
CONTROLS
TOUCH
SENSE
MODULATION
TABS
Before
proceeding
with
Operation
and
Adjustment
of
your
unit,
please
refer
to
page
10
for
Connection
Instructions.
LEVEL
ADJUST
M u . e „
This
rotary
control
(located
on
the
back
of
the
unit)
sets
the
overall
output
level,
or
volume,
of the
unit.
Smaller
changes
in
volume
may
be
made
with
the
VOLUME
control
on
the
Slide
Control
Panel.
This
rotary
control
(located
on
the
back
of the
unit)
provides
a
range
of
tuning
which
extends
more
than
one-half
octave.
This
flexibility
can
be
used
to
tune
your
MOOG
MINITMOOG
to
other
instruments,
transpose
to
different
keys,
or
even
provide a glissando
effect.
POWER
AND
INDICATOR
LIGHT
.
u
.
An
ON-OFF
power
switch
is
conveniently
located
on
the
front
panel,
with a red
light
which
indicates
when
the
power
is
ON.
OCTAVES
t
. . t
With
neither
tab
depressed,
your
MOOG
MINITMOOG
will
play
in
its
highest
pitch
level.
Depress
tab 1 ,
and
what
ever
you
play
on
the
keyboard
will
be
one
octave
lower.
Raise
tab
"1"
and
depress
tab
"2",
and
the
keyboard
pitch
level
is
lowered
another
octave.
Depress
both
tabs
and
the
pitch
level
is
lowered
still
a
third
octave.
Because
of
the
electronic
tailoring
of
the
sounds
to
the
requirements
of
each
pitch
level,
you
will
find
that the
effectiveness
of
every
sound
seems
to
change
magically
as
you
change
from
octave to
octave.
Try
all
sound
effects
in
all
four
pitch
levels.
SUSTAIN
. . .
This
"Quick-Set"
tab
allows
the
sound
of a note
to
"linger"
after
the
key
is
released.
It
provides
interesting
variations
to
the
special
voice
settings
described
in
this
Manual.
Minitmoog
Quick-Set
Voice
Tabs
TAURUS
GUITAR-1
VIOLIN
With
the
unit
connected
and
power
ON, a sound
can
be
heard
when a note
on
the
keyboard
is
struck,
even
though
no
voices
are
selected
and
all
slide
controls
are
set
at
"0"
(except
for
the
VOLUME
control).
The
controls
described
herein
will
add and
subtract
from
that
sound
in a multitude
of
combinations
available
for
your
exploration
-
shape
it,
change
its
attack
and
release,
raise
it,
or
lower
it.
We
suggest
that
you
play a phrase
or
two
with
each
of
the
twelve
"QUICK-SET"
VOICE
TABS
conveniently
located
on
the
front
of
the
unit.
Try
each
with
all
the
slide
controls
set
at
"0"
(except
for
VOLUME).
Exact
setting
of
slide
controls
for
any
particular
effect
will
depend,
not
only
on
your
musical
taste,
but
also
on
your
complete
electronic
reproduction
system
including
amplifiers,
speakers
and
other
components.
NOTE:
If
more
than
one
"QUICK-SET"
Voice
Tab
is
depressed
at
the
same
time
the
sound
will
be
that
controlled
by
the
Voice
Tab
farthest
to
the
left.
MUTE
This
voice
is a new
version
of
the
wah-wah
effect.
The
sound
approximates
a
double-acting
wah-wah,
or
"ooo-wah-ooo."
It
starts
with
an
emphasis
on
the
"lows",
moves
to
the
"highs"
and
returns.
Each
time a key
is
depressed
the
"ooo-wah-ooo"
sound
is
produced.
Try
it
in
each
octave.
TRUMPET
The
sounds
of a trumpet,
trombone,
or
tuba can
be
approximated
by
selecting
this
tab,
and
varying
it
with
other
controls.
Characteristic
of
this
voice
(and
some
of
the
other
"Quick-Set"
voices)
is a built-in
timbre
change
which
is
faster
in
the
upper
octaves
and
is
automatically
slower
in
the
lower
octaves
•
much
as
the attack
of a tuba
differs
from
that
of a trumpet.
This
attention to
the
authentic
details
of the
attack
in
different
octaves
is
a
unique
feature
of
the
Minitmoog.
Try
it
in
each
octave
setting.
OBOE
This
voice
provides
a
sound
similar
to
that
of a double
reed. In
the
top
octave
the
sound
is
oboe-like.
In
the
lower
octaves,
the
sound
of a bassoon
is
approximated.
You
will
note a slight
timbre
change
in
the
onset
of
the
tone
and a slow
attack.
CLARINET
The
hollow
reed
sound
and
the
soft
attack
of
the
traditional
clarinet
and
bass
clarinet
are
characteristic
of
this
voice -an
excellent
voice
in
all
octave
registers.
SAX
This
full
bodied
reed
sound
is
unique
to
the
Minitmoog.
It
combines
some
of
the
qualities
of a double
reed
wind
instrument
with
those
of a pipe
organ
with a little
sax
ophone
added.
In
the
lowest
registers,
it is
an
excellent
reproduction
of the
sound-
of
the
sarrusophone,
a
wind
instrument
popular
in
bands
of
the
early
1900's.
aa
we
TAURUS
This
voice
approximates
that
of a saxophone.
With
adjustment
of
other
controls
you
will
be
able
to vary
the
und
through
the
characteristics
of
alto
and
tenor,
bari-
ne,
and
bass
sounds
of
the
Taurus
Synthesizer.
VIOLIN
This
gentle
voice
with
its
slow
attack
can
be
made
to
simulate
violin,
viola,
cello,
and
even
some
of the
sounds
of
the
bass
violin.
GUITAR-1
This
sound
is
quite
percussive
with a lingering
decay.
It
is
most
useful
for
creating
guitar-like
or
harpsichord-
type
effects,
including
that
of a folk
guitar.
PIANO
In
the
upper
registers
this
voice
is
that
of
an
electronic
piano.
In
the
lower
registers
it
provides
an
interesting
sound
similar
to
that
of
an
electric
bass
guitar.
AIRES
Banjo
type
sounds
are
provided
with
the
hollow
sound
characteristic
of
this
voice.
In
the
lower
registers
it
can
simulate
the
plucked
sound
of
the
string
bass,
or
bass
violin.
GUITAR
-2
In
the
upper
octaves a fine
bell
sound
is
provided
by
this
voice.
In
the
lower
octaves,
the
huge
sound
of
a
large
carillon
can
be
reproduced.
LUNAR
This
versatile
voice
perhaps
is
most
characteristic
of
the
Moog
sounds.
It
provides,
in
its
various
adjust
ments, a wide
variety
of
timbre
changes
with
which
you
can
produce
many
popular
electronic
"Moog"
sound
effects.
It
is
most
effective
when
used
with
SUSTAIN.
Minitmoog
Modulation,
Oscillation
and
Touch
Controls
RATE
DEPTH
•B"
PITCH'
A/BMIX
TOUCH
SENSE
FILTER
TREMULANT
VIBRATO
MODULATION
The
two
function
tabs
labeled
MODULATION
on
the
front
of
the
unit
provide a selection
of
modulation
types.
The
two
MODULATION
slide
controls
on
the
slide
control
panel
adjust
the
RATE
and
DEPTH
of
modulation.
VIB
(VIBRATO)
This
tab
provides
a
frequency-modulation
vibrato
simi
lar
to
the
type used
in
electronic
organs.
However,
the
wide
range
of
effects
offered
by
the
two
slide
controls
extends
the
capability
of
this
effect
far
beyond
vibrato
and
into
the
realm
of
the
synthesizer.
When
the
VIB
tab
is
depressed,
the
basic
frequency
of a note
is
varied
(or
"wiggled")
to a degree
determined
by
the
DEPTH
control
and
at a rate
determined
by
the
RATE
control.
RATE
The
rate
of
modulation
may
be
varied
from
approx-
ately
one
second
at
"0"
to a rate
so
fast
that
at
10"
the
sound
becomes a buzz.
However,
even
at
ex
treme
settings,
the
basic
character
of
the
"QUICK-SET"
voices
is
still
apparent.
For
instance,
MUTE,
with
VIB
plus
RATE
at
10
becomes a BUZZ-WAH
type
of
effect.
With
slower
settings
it
is
easy
to
obtain
the
effect
of
trills
between
notes,
regardless
of the voice
selected.
DEPTH
This
control
adjusts
the degree
or
intensity
of
modu
lation.
For
vibrato
(VIB),
increasing
DEPTH
corresponds
to
greater
frequency
variation.
This
frequency
variation
may
be
adjusted
from
less
than
one-half
step
(on
the
scale)
to
more
than
one
octave.
For
tremulant
(TREM),
increasing
DEPTH
corresponds
to
greater
timbre
variation.
This
flexibility,
combined
with
the
RATE
control,
makes
possible
synthesis
of
such
effects
as
"out
of
tune"
strings,
huge
bells
whose
clanging
sounds
interfere
with
each
other,
quarter
tone
scales,
trumpet
"shake"
effects,
and a myriad
of
others.
TREM
(TREMULANT)
This
tab
provides
modulation
of
the
harmonic
content
of
the
tone.
The
harmonic
content,
or
timbre,
is
varied
at
a
rate
determined
by
the
RATE
control
and
with
an
intensity
determined
by
the
DEPTH
control.
NOTE:
VIB
and
TREM
can
be
used
together.
SYNC
This
tab
is
only
active
when
other
SYNC
tab
switch
is
also
down.
Raises
pitch
of B tone
osciliator as a key
is
depressed
harder
producing
a
phasing
effect.
PITCH
This
tab
bends
pitch
of
both A and B tone
oscillators
up
to
an
interval
of
at
least
seven
semitones
when a key
is
depressed
harder.
FILTER
This
tab
adds
familiar
Moog
"wah"
to
most
voices
when
pressure
on
the
keys
is
increased.
This
effect
adds
directly
to
the
effect
produced
by
the
FILTER
BRIGHT
NESS
slide
control.
MOD
This
tab
allows
either
vibrato
or
tremolo
to
be
added
to
the
tone
as
the
pressure
on
the
keys
is
increased.
The
DEPTH
slide
control
in
this
mode
acts
as a touch
sensitiv
ity
control
and
the
MODULATION
RATE
slide
control
sets
the
speed
of
the
effect.
This
tab
switch
has
an
effect
only
if
the
MODULATION
VIB
or
MODULATION
TREM
tab
switch
is
also
depressed.
TOUCH
SENSE
This
control
regulates
the
range
of
expressive
effects
when
additional
pressure
is
exerted
on
the
keys
for
SYNC,
PITCH
and
FILTER
(brightness)
modes.
"B"
PITCH
This
control
varies
pitch
ol B tone
producing
oscillator
over a two
octave
range.
A/B
MIX
Controls
mixing
of A and B tone source
oscillator
outputs. A only
or B only
occur
at
the
CCW
and
CW
extremes
of
rotation,
respectively.
Q
Minitmoog
Slide
Control
Panel
GLIDE
VOLUME
BRIGHTNESS
DECAY
ATTACK
FILTER
CONTROLS
u
.
.
Once a "Quick-Set"
tab
voice
selection
is
made,
further
refinement
and
adjustment
of
that
voice
may
be
made
oy
using
the
three
slide
controls
labeled
FILTER.
ATTACK
This
controls
the
speed
of
the
timbre
change
associated
with
the
onset
of
the
voice,
and/or
the
timbre
change
associated
with
the
release
of
that
voice.
The
wide
range
of
this
control
can
provide
both
slow
settings
(useful
for
simulation
of
bass
violin
or
tuba
effects)
and
fast
timbre
change
settings
(which can
provide
wild
chirping
effects).
DECAY
This
acts
as a brightness
control,
but
it
has
such
a
wide
range
that
it
can
have
major
effect
on
the
basic
sound
itself.
Your
choice
may
lie
anywhere
between
adding
in
all
of
the
high
harmonics
you
wish,
or
elim
inating
them.
BRIGHTNESS
This
control
adds a resonance
frequency
area
to
the
spectrum
of
the
tone.
At
"0",
spectrum
of the
"Quick-
Set"
sound
is
unchanged.
As
the
control
is
pushed
forward,
the
intensity
of
the
sound
within a pre-selected
resonance
area
is
increased.
At
maximum,
there
is a well
defined
narrow
sharp
peak
in
the
spectrum
of
the
tone.
FILTER
CONTROLS
SUMMARY
Remember,
the
"Quick-Set"
tabs
establish
an
overall
range
of
sound
and
the
three
Filter
slide
controls
give
you a wide
selection
and
control
within
the
limitations
of
that
range.
Try
this:
1.
Depress
TRUMPET
tab,
and
set
the
slide
controls
at
"0".
2.
Play a few
notes
on
the
keyboard.
3.
Play
again
with
various
settings
of
the
DECAY
slide
pot.
The
range
of
sound
will
be
from
that
of a very
dull
trumpet
to a very
brassy
one.
4.
Now
do
the
same
with
the
BRIGHTNESS
control.
The
sound
will
range
through
cornet,
trumpet,
and
flugelhorn
characteristics.
5.
Repeat
with
various
settings
of
the
ATTACK
control.
It
will
show
the
wide
range
of
contoured
timbers
in
the
onset
of
the
tones.
ADDITIONAL
CONTROLS
MODULATION
CONTROLS
See
discussion
under
MODULATION
on
page
3.
GLIDE
This
is
one
of
the
most
interesting
of
the
Moog
effects.
Depress
the
GLIDE
tab
and
set
the
GLIDE
slide
control
at
6.
Play
any
note
on
the
keyboard.
Release
this
note
and
quickly
play a second
note
some
distance
away.
The
sound
automatically
glissandos
from
the
first
note
to the
second.
The
setting
of
the
slide
control
determines
the
speed
of
the
glissando,
{10
is
slow -1
is
fast).
Try a melody
of
detached
notes
and
notice
the
succession
of
glide
attacks.
VOLUME
The
VOLUME
slide
control
provides
finger-tip
adjust
ment
of
fine
gradations
of
the
Minitmoog
output.
Major
changes
in
sound
level
are
obtained
by
means
of
the
rotary
knob
on
the
back
of
the
unit.
Satellite
Controls
SUOE
CONTROLS
PANEL
GLIDE
VOLUME
CONTROL CONTROL
LEVEL &
TUNE
CONTROLS
(LOCATED
ON
REAR
PANEL)
ACCESSORY & OUTPUT
CONNECTIONS
SOLO
(LOCATED
ON REAR
PANEL)
KEYBOARD
GLIDE,
SUSTAIN
TABS
Before
proceeding
with
Operation
and
Adjustment
of
your
unit,refer
to
page
10
for
Connection
Instructions.
LEVEL
ADJUST
This
rotary
control
(located
on
the
back
of
the
uniOsets
the
overall
output
level,
or
volume,
of
the
unit.
Smaller
changes
in
volume
may
be
made
with
the
VOLUME
control
on
the
Slide
Control
Panel.
\
TUNE
This
rotary
control
(located
on
the
back
of
the
unit)
provides
a
range
of
tuning
which
extends
more
than
one-half
octave.
This
flexibility
can
be
used
to
tune
your
MOOG
SATELLITE
to
other
instruments,
transpose
to
different
keys,
or
even
provide
a
glissando
effect.
POWER
AND
INDICATOR
LIGHT
An
ON-OFF
power
switch
is
conveniently
located
on
the
front
panel,
with
a
red
light
which
indicates
when
the
power
is
ON.
OCTAVES
With
neither
tab
depressed,
your
MOOG
SATELLITE
will
play
in
its
highest
pitch
level.
Depress
tab
"V,
and
whatever
you
play
on
the
keyboard
will
be
one
octave
lower.
Raise
tab
"1"
and
depress
tab
"2",
and
the
keyboard
pitch
level
is
lowered
another octave.
Depress
both
tabs
and
the pitch
level
is
lowered
still
a
third
octave.
Because
of
the
electronic
tailoring
of
the
sounds
to
the
requirements
of
each
pitch
level,
you
will
find
that
the
effectiveness
of
every
sound
seems
to
change
magically
as
you
change
from
octave
to
octave.
Try
all
sound
effects
in
all
four
pitch
levels.
SUSTAIN
This
"Quick-Set"
tab
allows
the
sound
of
a
note
to
"linger"
after
the
key
is
released.
It
pro
vides
interesting
variations
to
the
special
voice
settings
described
in
this
Manual.
Satellite
Quick-Set
Voice
Tabs
BRASS
VOICES'
•MUTE
•
OPEN
REED
VOICES
•THIN
•HOLLOW
•
FULL
•
BRIGHT
STRING VOICES
•BOW
•
PLUCK
•STRIKE
•
PICK
BELL
With
the
unit
connected
and
power
ON, a sound
can
be
heard
when a note
on
the
keyboard
is
stiuck.
even
though no
voices
are
selected
and
all
slide
controls
are set
at
"0"
(except
for
the
VOLUME
control
i.
The
controls
described
herein
will
add and
subtract
from
that
sound
in a multitude
of
combinations
<iv.ii
Lib
k*
tor
your
exploration
-
shape
it,
change
its
attack
and
release,
raise
it,
or
lower
it.
We
suggest
Unit
you
play a phrase
or
two
with
each
of
the
twelve
"QUICK-SET"
VOICE
TABS
conveniently
located
on
the
front
ol
ihc
unit.
Try
each
with
all
the
slide
controls
set
at
"0"
(except
for
VOLUME).
Exact
setting
of
slide
controls
for
any
particular
effect
will
depend,
not
only
on
your
musical
taste,
but
also
on
your
complete
electronic
reproduction
system
including
amplifiers,
speakers
and
other
components.
NOTE:
If
more
than
one
"QUICK-SET"
Voice
Tab
is
depressed
at
the
same
time
the
sound
will
be
that
controlled
by
the
Voice
Tab
farthest
to
the
left.
MUTE
BRASS
This
voice
is a new
version
of
the
wah-wah
effect.
The sound
approximates
a
double-acting
wah-wah,
.or
"ooowah-ooo."
It
starts
with
an
emphasis
on
the
"lows",
moves
to
the
"highs"
and
returns.
Each
time
a
key
is
depressed
the
"ooo-wah-ooo"
sound
is
pro
duced.
Try
it
in
each
octave.
OPEN
BRASS
The
sounds
of a trumpet,
trombone,
or
tuba
can
be
approximated
by
selecting
this
tab,
and
varying
it
with
other
controls.
Characteristic
of
this
voice
(and
some
of
the
other
"Quick-Set"
voices)
is a built-in
timbre
change
which
is
faster
in
the
upper
octaves
and
is
automatically
slower
in
the
lower
octaves
—
much
as
the
attack
of a tuba
differs
from
that
of
a
trumpet.
This
attention
to
the
authentic
details
of
the
attack
in
different
octaves
is a unique
feature
of
the
Satellite.
Try
it
in
each
octave
setting.
THIN
REED
This
voice
provides a sound
similar
to
that
of
a
double
reed.
In
the
top
octave
the
sound
is
oboe-like.
In
the
lower
octaves,
the
sound
of a bassoon
is
approximated.
You
will
note a slight
timbre
change
in
the
onset
of
the
tone
and a slow
attack.
HOLLOW
REED
The
hollow
reed
sound
and
the
soft
attack
of
the
raditional
clarinet
and
bass
clarinet
are
character
istic
of
this
voice -an
excellent
voice
in all
octave
registers.
FULL REED
This
full
bodied
reed
sound
is
unique
to
the
Satellite.
It
combines
some
of
the
qualities
of
a
double
reed
wind
instrument
with
those
of a pipe
organ
with a little
saxophone
added.
In
the
lowest
registers,
it
is
an
excellent
reproduction
of
the
sound
of
the
sarrusophone,
a
wind
instrument
popular
in
bands
of
the
early
1900's.
BRIGHT
REED
This
voice
approximates
that
of a saxophone.
With
adjustment
of
other
controls
you
will
be
able
to
vary
the
sound
through
the
characteristics
of
alto
and
tenor,
baritone,
and
even
bass
saxophone.
BOW
STRING
This
gentle
voice
with
its
slow
attack
can
be
made
to
simulate
violin,
viola,
cello,
and
even
some
of
the
sounds
of
the
bass
violin.
PLUCK
STRING
This
sound
is
quite
percussive
with a lingering
decay.
It
is
most
useful
for
creating
guitar-like
or
harpsichord-type
effects,
including
that
of
a folk
guitar.
STRIKE
STRING
In
the
upper
registers
this
voice
is
that
of
an
electronic
piano.
In
the
lower
registers
it
provides
an
interesting
sound
similar
to
that
of
an
electric
bass
guitar.
PICK
STRING
Banjo
type
sounds
are
provided
with
the
hollow
sound
characteristic
of
this
voice.
In
the
lower
registers
it
can
simulate
the
plucked
sound
of
the
string
bass,
or
bass
violin.
BELL
In
the
upper
octaves a fine
bell
sound
is
provided
by
this
voice.
In
the
lower
octaves,
the
huge
sound
of a large
carillon
can
be
reproduced.
LUNAR
This
versatile
voice
perhaps
is
most
characteris
tic
of
the
Moog
sounds.
It
provides,
in
its
various
adjustments,
a
wide
variety
of
timbre
changes
with
which
you
can
produce
many
popular
electronic
"Moog"
sound
effects.
It
is
most
effective
when
used
with
SUSTAIN.
Satellite
Modulation
RATE—'
DEPTH
Tfrf
REPEAT-*
UTREMULANT
' I VIBRATO
The
four
function
tabs
labeled
MODULATION
on
the
front
of
the
unit
provide a selection
of
modulation
types.
The
two
MODULATION
slide
controls
on
the
slide
control
panel
adjust
the
RATE
and
DEPTH
of
modulation.
VIB
(VIBRATO)
This
tab
provides a frequency-modulation
vibrato
similar
to
the
type
used
in
electronic
organs.
However,
the
wide
range
of
effects
offered
by
the
two
slide
controls
extends
the
capability
of
this
effect
far
beyond
vibrato
and
into
the
realm
of
the
synthesizer.
When
the
VIB
tab
is
depressed,
the
basic
frequency
of a note
is
varied
(or
"wiggled")
to a degree
deter
mined
by
the
DEPTH
control
and
at a rate
determined
by
the
RATE
control.
RATE
The
rate
of
modulation
may
be
varied
from
approx
imately
one second
at
"0"
to
a rate
so
fast
that
at
"10"
the
sound
becomes a buzz.
However, even
at
extreme
settings,
the
basic
character
of
the
"QUICK
SET"
voices
is
still
apparent.
For
instance,
MUTE
BRASS,
with
VIB
plus
RATE
at
10
becomes a BUZZ-WAH
type
of
effect.
With
slower
settings
it
is
easy
to
obtain
the
effect
of
trills
between
notes,
regardless
of
the
voice
selected.
DEPTH
This
control
adjusts
the
degree
or
intensity
of
modulation.
For
vibrato
(VIB),
increasing
DEPTH
corresponds
to
greater
frequency
variation.
This
frequency
variation
may
be
adjusted
from
less
than
one-half
step
(on
the
scale)
to
more
than
one
octave.
For
tremulant
(TREM),
increasing
DEPTH
corresponds
to
greater
timbre
variation.
This
flexibility,
combined
with
the
RATE
control,
makes
possible
synthesis
of
such
effects
as
"out
of
tune"
strings,
huge
bells
whose
clanging
sounds
interfere
with
each
other,
quarter
tone
scales,
trumpet
"shake"
effects,
and a myriad
of
others.
TREM
(TREMULANT)
This
tab
provides
modulation
of
the
harmonic
content
of
the
tone.
The
harmonic
content,
or
timbre,
is
varied
at a rate
determined
by
the
RATE
control
and
with
an
intensity
determined
by
the
DEPTH
control.
NOTE:
VIB
and
TREM
can
be
used
together.
REP
(REPEAT)
The
repeat
tab
affects
only
those
"QUICK -SET"
voices
which
have
built-in
timbre
changes.
The
timbre
change
associated
with a specific
voice
will
be
repeated
over
and
over
again
at a speed
controlled
by
the
RATE
slide
control.
This
is
easily
demonstrated
by
depressing
MUTE
BRASS,
REP,
OCTAVE 1 and
2,
and
setting
RATE
at
0.
Play a sustained
tone,
then
slowly
move
the
slide
control
to
10
and
return,
while
sustaining
the
tone.
NOTE:
The
DEPTH
slide
control
has
no
effect
on
the
REP
function.
\\s\rui
This
control
provides a most
versatile
tool
in
achieving
the
distinctive
sounds
associated
with
the
MOOG
synthesizer.
It
affects
the
type
of
modu
lation
obtained
by
two
of
the
other
MODULATION
functions,
VIBRATO
and
TREMULANT.
When
this
tab
is in
the
up
position,
VIB
and
TREM
are
with a square-wave
putioui.
The
variation
of
frequency
(VIB),
or
variation
ol
timbres
(TREM),
will
be
very
abrupt
and
choppy.
with
discon
tinuities.
With
VIB,
for
instance, a defmiiivn
variation
in
frequency
can
be
obtained,
like a trill
When
+1/1
rut
is
depressed, a sine
wave
type
of
modulation
is
obtained
which
provides a smooth
variation
of
timbre
or
frequency
-
almost a glissando.
The
difference
between
the
two
effects
is
easily
discernible
in
the
following
ciniructunstically
M00G-
type
settings.
Depress
ii/irut . MUTE
BRASS,
OCTAVE
2,
VIB,
set
RATE
at
3.
and
DEPTH
at
6.
Depress
any
key
on
the
keyboard
and
listen
to
the
smooth
variation
in
frequency
as
you
keep
your
finger
on
the
key.
Then
raise
the
tab
marked
♦b^rut
and
observe
the
abrupt
variation
in
frequency.
Repeat
the
above
steps
with
TREM
instead
of
VIB,
and
then
combine
the
two.
8
Satellite
Slide
Control
Panel
L
EMPHASIS
FILTER
CONTROLS
Once a "Quick-Set"
tab
voice
selection
is
made,
further
refinement
and
adjustment
of
that
voice
may
be
made
by
using
the
three slide
controls
labeled
FILTER.
CONTOUR
This
controls
the
speed
of
the
timbre
change
associated
with
the
onset
of
the
voice,
and/or
the
timbre
change
associated
with
the
release
of
that
voice.
The
wide
range
of
this
control
can
provide
both
slow
settings
(useful
for
simulation
of
bass
violin
or
tuba
effects)
and
fast
timbre
change
settings
(which
can
provide
wild
chirping
effects).
COLOR
This
acts
as a brightness
control,
but
it
has
such
a
wide
range
that
it
can
have
major
effect
on
the
basic
sound
itself.
Your
choice
may
lie
anywhere
between
adding
in a|l
.of
the
high
harmonics
you
wish,
or
eliminating
them.
EMPHASIS
This
control
adds a resonance
frequency
area
to
the
spectrum
of
the
tone.
At
"0",
spectrum
of
the
"Quick-Set"
sound
is
unchanged.
As
the
control
is
pushed
forward,
the
intensity
of
the
sound
within
a
pre-selected
resonance
area
is
increased.
At
maxi
mum,
there
is a well
defined
narrow
sharp
peak
in
the
spectrum
of
the
tone.
FILTER
CONTROLS
SUMMARY
Remember,
the
"Quick-Set"
tabs
establish
an
overall
range
of
sound
and
the
three
Filter
slide
controls
give
you a wide
selection
and
control
within the
limitations
of
that
range.
Try
this:
1.
Depress
OPEN
BRASS
controls
at
"0".
tab,
and
set
the
slide
2.
Play a few
notes
on
the
keyboard.
3.
Play
again
with
various
settings
of
the
COLOR
slide
pot.
The
range
of
sound
will
be
from
that
of
a
very
dull
trumpet
to a very
brassy
one.
4.
Now
do
the
same
with
the
EMPHASIS
control.
The
sound
will
range
through
cornet,
trumpet,
and
flugelhorn
characteristics.
5.
Repeat
with
various
settings
of.
the
CONTOUR
control.
It
will
show
the
wide
range
of
contoured
timbres
in
the
onset
of
the
tones.
ADDITIONAL
CONTROLS
MODULATION
CONTROLS
See
discussion
under
MODULATION
on
page
8.
GLIDE
This
is
one
of
the
most
interesting
of
the
Moog
effects.
Depress
the
GLIDE
tab
and
set
the
GLIDE
slide
control
at
6.
Play
any
note
on
the
keyboard.
Release
this
note
and
quickly
play a second
note
some
distance
away.
The
sound
automatically
glissandos
from
the
first
note
to
the
second.
The
setting
of
the
slide
control
determines
the
speed
of
the
glissando,
(10
is
slow -1
is
fast).
Try a melody
of
detached
notes
and
notice
the
succession
of
glide
attacks.
VOLUME
The
VOLUME
slide
control
provides
finger-tip
adjustment
of
fine
gradations
of
the
Satellite
output.
Major
changes
in
sound
level
are
obtained
by
means
of
the
rotary
knob
on
the
back
of
the
unit.
9
Accessory
and
Connections
For
operation,
the
Synthesizer
unit
should
be
placed
on a horizontal
surface
in a location
which
will
not
interfere
with
its
operation.
NOTE:
Avoid
placement
in
close
proximity
to
electronic
circuitry,
as
on
the
top
of
some
electronic
organs,
because
excessive
hum
may
result.
LO-LEVEL
OUTPUT
130
millivolts
RMS),
Phone
Jack
designed
for
use
with
Guitar
Amplifier,
P.A.
Systems,
etc.
HI-LEVEL
OUTPUT
(1
volt
RMS),
RCA
Phono
Jack
designed
for
use
with
Electronic
Organs.
("Y"
Adapter
and
Accessory
extension
cable
are
included
with
your
unit).
REAR
PANEL
ACCESSORY
EXTENSION
CABLE
ORGAN
AMPLIFIER
RIGHT
OR
MAIN
CHANNEL
INPUT
PLUG
RIGHT
OR
MAIN
CHANNEL
INPUT
JACK
.FROM
ORGAN
Connection
Instructions
SINGLE
CHANNEL
ORGANS
(MONAURAL)
Disconnect
the
RCA
Phono
plug
from
Amplifier
Input
Jack
and
insert
the
"Y"
Adapter
plug
into
the
Amplifier
inpui
Jack.
Connect
Accessory
extension
cable
plug
into
"Y"
Adapter
socket
and
insert
the
plug
on
the
other
end
ol
the
extension
cable
into
the
HI-LEVEL
OUTPUT
jack
on
your
Synthesizer
unit.
Connect
the
organ
plug
(previouslv
removed)
into
the
other
"Y"
Adapter
socket.
DUAL
CHANNEL
ORGANS
(STEREO)
Disconnect
the
RCA
Phono
plug
from
the
Right
of
Main
Channel
Amplifier
Input
Jack
and
insert
"Y"
AOaptoc
plug
into
Right
or
Main
Channel
Input
Jack.
Connect
the
Accessory
extension
cable
plug
into
the
"Y"
Adapter
socket
and
insert
the
plug
on
the
other
end
of
the
extension
cable
into
HI-LEVEL
OUTPUT
jack
on
your
Synthesiser
unit.
Connect
the
Right
or
Main
Channel
plug
(previously
removed)
into
the
other
"Y"
Adapter
socket.
NOTE:
Do
not
connect
the
Synthesizer
into
Leslie
or
Left
Channel
Input.
FILTER
CONTROL
INPUT
This
jack
is
provided
for
the
control
of
the
Timbre
with a Moog
Pedal
controller.
ACCESSORY
SOCKET
,
x
Permits
the
attachment
of a Foot
Pedal
to
control
several
Synthesizer
features.
(Consult
your
dealer
for
availability
of
Moog
Accessories).
10
Care
of
Your
Synthesizers
Your
MOOG
Synthesizer
is
carefully
designed
to
give
you
maximum
pleasure
and
satisfaction
with a minimum
of
care.
Following
these
tips
on
the
care
of
your
Synthesizer
will
help
keep
it
"showroom
new."
■
LOCATION
As
with
any
electronic
instrument,
avoid
placement
in
direct
or
prolonged
sunlight.
Normal
variation
of
temper
ature
will
not
affect
the
tuning
or
electronic
circuitry
of
the
synthesizer.
Storage
location
should
be
chosen
to
avoid
placement
in
front
of
hot
air
registers,
or
beside
an
outside
doorway
in
winter,
as
these
elements
may
affect
the
finish
of
the
cabinet.
•
CABINET
Quality
hardwoods
are
used
in
your
MOOG
Synthesizer.
Therefore,
a
minimum
amount
of
care
wijl
insure
you
of
having
a
piece
of
furniture
that
will
retain
its
beauty.
An
occasional
dusting
with a soft,
dry
cloth
should
remove
both
fingerprints
and
dulling
film.
To
clean
the
keys
a soft
cloth
dampened
in a mild
soap
solution
should
remove
even
the
most
persistent
stains.
Under
no
circumstances
should
solvents
or
cleaning
fluids
be
used
to clean
keys
or
cabinet.
■
POWER
REQUIREMENTS
This
instrument
must
be
operated
from a standard
120
VAC
60Hz
power
outlet.
Normal
line
voltage
variation
will
not
affect
its
operation.
Power
requirements
of
this
unit
are
very
low.
All
solid
state
circuits
are
operated
at
a
very
low
voltage
and
component
life
is
therefore
extended.
■
SAFETY
Your
MOOG
Synthesizer
has
been
designed
for
maximum
safety
in
its
operation
and
trouble
free
performance.
However,
repair
or
service
of
electronic
products
should
be
done
by
qualified
personnel
familiar
with
the
hazards
relating
to
electricity
and
electronic
circuitry.
The
risk
of
repair
or
service
must
not
be
assumed
by
the
customer.
Your
dealer
will
provide
a
competent,
experienced
service
technician
for
that
purpose.
Please
contact
your
dealer,
if
your
unit
needs
repair
or
service.
■
CONCLUSION
And
now
as
you
play
....
Let
us
offer
you
our
best
wishes
for a happy
and
rewarding
experience
with
your
MOOG
Synthesizer.
We
know
it
will
bring
you
great
pleasure
and
creative
satisfaction.
11
TECHNICAL
SERVICE
SECTION
for
MINITMOOG/
SATELLTE
Minitmoog
Model
300A
Satellite
Model
5330
12
CONTENTS
SECTION
PAGE
1
INTRODUCTION
15
2
CIRCUIT
DESCRIPTION
15
2.1
GENERAL
15
2.2
POWER
SUPPLY
15
2.3
KEYBOARD
CIRCUIT
16
2.4
OSCILLATOR
18
2.5
BAND
PASS
FILTER
20
2.6
LOW
PASS
FILTER
20
2.7
VOLTAGE
CONTROLLED
AMPLIFIER
20
2.8
AMPLITUDE
CONTOUR
GENERATOR
21
2.9
FILTER
CONTOUR
GENERATOR
22
2.10
MODULATION
OSCILLATOR
22
2.11
TOUCH
SENSOR
•
22
3
DISASSEMBLY,
VISUAL
INSPECTION
AND
REASSEMBLY
23
3.1
DISASSEMBLY
23
3.2
VISUAL
INSPECTION
23
3.3
PRINTED
CIRCUIT
BOARD
REMOVAL.
23
3.4
REASSEMBLY
,
25
4
TUNING
AND
CALIBRATION
PROCEDURES
25
4.1
GENERAL
25
4.2
OSCILLATOR
TUNING
25
4.3
VOICE
CALIBRATION
29
5
OPERATING
CONTROLS,
INDICATORS
AND
CONNECTORS
31
6
KEYBOARD
MAINTENANCE
AND
ADJUSTMENT
34
6.1
CONTACTS
35
6.2
KEYS
35
6.3
TOUCH
SENSOR
7
TROUBLESHOOTING
GUIDE
37
7.1
POWER
SUPPLY
37
7.2
SOUND
CHAIN
38
7.3
CONTROL
CIRCUITS
40
7.4
OSCILLATOR
TUNING
41
8
MODIFICATIONS
42
8.1
SERVICE
BULLETIN
802
42
8.2
TOUCH
SENSOR
BAR
42
8.3
INSTALLATION
OF
NEW
OR
REBUILT
TOUCH
SENSOR
BAR
45
9
REPLACEMENT
PARTS
LIST
46
10
BLOCK
AND
SCHEMATIC
DIAGRAMS
50
13
LIST
OF
ILLUSTRATIONS
FIGURE
TITLE
PAGE
NO.
2-1
Keyboard
Trigger
Voltage
Waveforms
17
2-2
Emitter
of
Q46
18
2-3
Synchronization
of
Oscillator
B
to
Oscillator
A
19
2-4
Emitter
Voltage
of
Q35
21
2-5
Source
Voltage
of
Q32
21
3-1
Minitmoog
Printed
Circuit
Board
Location
(Inside
View)
24
3-2
Minitmoog
Cover
and
Printed
Circuit
Board
Locations
(Bottom
Views)
....
24
4-1
Minimal
Test
Setup
for
Tuning
25
4-2
Two
Channel
Oscilloscope
Test
Setup
for
Tuning
26
4-3
Main
Board
No. 1 Adjustment
Controls
and
Oscilloscope
Test
Point
Locations
26
4-4
Trigger
at
Collector
of
Q8
27
4-5
Oscillator
B
Trimpot
Locations
(Board
No.
5)
28
4-6
Square
Wave
at
Junction
of
R44
and
R119
29
4-7
Band
Pass
Filter
Q
and
Fc
at
Q41
Source
29
4-8
Filter
Contour
at
Q20
Source
30
4-9
Loudness
Attack
at
Junction
of
R165
and
R166
30
4-10
Loudness
Decay
at
Junction
of
R165
and
R166
30
8-1
Disassembly
of
Minitmoog
42
8-2
Minitmoog
Disassembled
43
8-3
Sensor
Removal
43
8-4
Sensor
Removed
from
Top
Support
44
8-5
Modification
Material
44
8-6
Touch
Sensor
Bar
Reassembled
45
10-1
Minitmoog
Schematic
Diagram
51
10-2
Minitmoog
Block
Diagram
52
10-3
Minitmoog
Printed
Circuit
Board
Assemblies
52
10-4
Minitmoog
Touch
Sensor
Board
Assembly
No. 4 Schematic
Diagram
53
10-5
Minitmoog
Oscillator
Board
Assembly
No. 5 Schematic
Diagram
53
10-6
Satellite
Schematic
Diagram
54
10-7
Satellite
Printed
Circuit
Board
Assemblies
55
10-8
Satellite
Block
Diagram
56
l'i
14
SECTION
1
INTRODUCTION
This
manual
provides
servicing
and
parts infor
mation
for
Minitmoog
Synthesizer
Model
300A
and
Satellite
Synthesizer
Model
5330,
manufactured
by
Moog
Music
Inc.,
2500
Walden
Avenue,
Buffalo,
New
York
14225.
This
manual
was
written
basically
for
the
Minitmoog
Synthesizer
which
includes
the
touch
sensor
board 4 and
oscillator
B
board 5 not
found
in
the
Satellite
Synthesizer.
Differences
in
operating
control
panel
markings
are
indicated
in
Section
5.
Any
major
differences
will
be
noted.
The
Minitmoog
and
Satellite
Synthesizers
are
monophonic
live
performance
synthesizers
intended
primarily
as
auxiliary
instruments
for
keyboardists
and
features
a
dozen
"QUICK-SET"
tabs
that
allow
for
instan
taneous
changes
among
various
voices
preset
with
in
the
instrument.
The
sound
producing
chain
of
the
Synthesizers
consists
of
an
"A"
oscillator
that
produces
both
sawtooth
and
rectangular
waveforms,
a
"B"
scillator
(Minitmoog
only)
that
produces
only
saw
tooth
waveforms,
a
band
pass
filter,
a
low
pass
filter
and a variable
gain
amplifier.
All
five
of
these
circuits
in
the
sound
producing
chain
are
voltage
controlled
and
the
remaining
circuitry
is
devoted
to
producing
appropriate
control
voltages.
The
keyboard
circuit
produces
one
pitch
control
voltage,
the
magnitude
of
which
depends
on
which
key
is
depressed.
In
addition,
the
keyboard
produces
a
trigger
voltage
whenever
one
or
more
of
the
keys
are
depressed.
The
modulating
oscillator
produces
triangular
waveforms
for
modulating
the
oscillators
and
filters.
Two
contour
generators
produce
voltages
that
rise
and
fall
each
time a key
is
depressed.
One
contour
generator
sweeps
one
of
the
filters
while
the
other
sweeps
the
amplifier.
A
resistor
matrix
determines
the
nominal
values
of
the
voltage-controlled
parameters.
The
power
supply
delivers
±
18
volts
unregulated
and
± 9 volts
regulated.
Refer
to
page
52.
The
resistor
matrix
has
fifteen
input
rows
and
twelve
output
columns. A row
is
on
when
+9
volts
is
applied
to
it
and
off
when
it is
open
circuited.
The
two
upper
rows
are
connected
to
the 2 OCT
and 1 OCT
tab
switches,
respectively,
and
shorten
the
contour
times
and
raise
filter
frequencies
when
on.
The
remaining
rows
are
for
the
quick
set
voices
and
only
one
can
be
on
at a time.
The
column
outputs
are
applied
to
low
impedance
points
in
the
circuitry.
Of
the
twelve
matrix
output
columns,
eight
supply
control
currents
for
continuously
variable
parameters,
while
the
remaining
four
supply
switching
current
to
determine
circuit
states.
SECTION
2
CIRCUIT
DESCRIPTION
2.1
GENERAL
The
main
circuit
board
mounts
underneath
the
keyboard
and
contains
a
large
portion
of
the
Synthesizer
circuitry.
All
connections
to
this
board
are
made
through
Molex
connectors.
Looking
at
the
board
from
the
component
side
with
the
connectors
along
the
top
edge,
the
left
connector
is
designated
"A"
and
the
right
connector
is
designated
"B"
with
the
pins
numbered
from 1 to
24
starting
with
the
ief t pin
on
each
connector.
Block
diagrams,
schematic
diagrams
and
printed
circuit
board
diagrams
are
illustrated
in
Section
10
for
quick
reference.
2.2
POWER
SUPPLY
The
unregulated
portion
of
the
power
supply
is
located
on
power
supply
board
No. 2 and
is
completely
conventional.
The
nominal
total
load
supplied
from
each
of
the
unregulated
voltages
is
45
milliamperes.
The
positive
and
negative
voltage
regulator
circuits
for
the
power
supply
are
located
on
main
board
No. 1 .
The
positive
power
supply
voltage
regulator
consists
of
IC1
and
associated
components
and
its
circuitry
is
completely
conventional.
The
supply
delivers
55
or
60
milliamperes
before
voltage
15
developed
across
current
sense
resistor
R2
limits
the
current.
The
negative
power
supply
voltage
regulator
consists
of
IC2,
Ql
and
associated
components
and
adjusts
its
output
to
have
the
same
magnitude
as
the
regulated
+9
volt
output.
No
current
limiting,
other
than
that
supplied
by
R8,
is
provided.
2.3
KEYBOARD
CIRCUIT
The
keyboard
circuit
consists
of
IC3
thru
IC7,
IC9,
IC10
and
related
circuitry.
The
keyboard
contains
a
string
of
thirty-six
100-ohm
resistors
connected
between
pins
A5
and
A6.
The
current
through
the
resistor
string
is
regulated
by
IC7
so
that
the
drop
across
R79
and
R80
is
exactly
4.5
volts.
R79
is
set
so
that
the
voltage
at
pin
A6
is
exactly
-4.5
volts.This
sets a scale
factor
of 3 volts
per
octave
(250
mv
per
semitone).
2.3.1
TRIGGERING
(SINGLE)
The
voltage
at
the
keyboard
buss
is
applied
to
voltage
follower
IC4.
The
keyboard
buss
voltage
rises
to
approximately
7
volts
(detail
A,
Figure
2-1)
when
no
key
is
depressed
because
of
R53.
The
output
of
voltage
follower
IC4
is
applied
to
comparator
IC5
whose
output
swings
from
-16
to
+7
volts
whenever
the
input
goes
below
+4.8
volts
(detail
B).
Q5
and
Q6
comprise
a
monostable
multivibrator
producing
a
pulse
of
approximately
20
milliseconds
duration
(detail
C).
When
the
output
of
IC5
swings
positive,
a
positive
spike
is
applied
through
C7
and
D7
to
the
base
of
Q6,
initiating
a
20
millisecond
pulse.
R63,
R73
and
R72
are
proportioned
so
that
Q7
conducts
only
when
the
output
of
IC5
is
positive
and
the
output
of
the
monostable
multivibrator
(the
collector
of
Q5)
is
negative.
That
is,
Q7
begins
to
conduct
approxi
mately
20
milliseconds
after
a
key
is
depressed
and
stops
conducting
as
soon
as
all
keys
are
released.
When
Q7
conducts,
Q8
is
turned
on
and
the
voltage
at
its
collector
rises
from 0
to
+9
volts.
When
this
happens,
C13
discharges
through
R61
producing
a
ramp
voltage
at
the
base
of
Q4
that
decreases
from
+9
volts
to
-0.6
volt
in
approximately
20
milliseconds
(detail
E).
Emitter
follower
Q4
supplies
a
current
through
R62
and
Q3
to
turn
on
IC10.
IC10
and
Q51
with
associated
circuitry
comprise
a
sample
and
hold
circuit.
When
the
current
ramp
is
applied
to
pin 5 of
IC10,
the
voltage
at
the
source
of
Q51
rapidly
approaches
that
at
the
output
of
IC4.
As
soon
as
the
base
of
Q4
drops
below
0.8
volt,
the
bias
current
being
applied
to
IC10
through
Q3
drops
to
zero
and
the
voltage
at
the
source
of
Q51
remains
constant.
As
long
as
the
output
of
IC5
remains
positive
(that
is,
as
long
as
any
key
is
depressed),
a
very
small
bias
current
of
approximately
50
nanoamperes
flows
through
R59
allowing
IC10
to
supply
a
small
current
to
C5
keeping
its
voltage
constant.
As
soon
as
all
keys
are
released,
the
output
of
IC5
goes
negative
and
IC10
is
virtually
completely
shut
off.
Thus,
when
only
one
key
at a time
is
depressed,
the
voltage
at
the
source
of
Q51
begins
to
approach
the
new
key
voltage
approximately
20
milliseconds
after
the
key
is
depressed
and
this
voltage
is
equal
to
the
new
key
voltage
well
before the
ramp
current
turning
IC10
on
goes
to
zero.
As
long
as a
key
is
depressed,
the
correct
voltage
at
the source
of
Q51
is
maintained
by
the
small
trickle
current
going
through
R59.
When
the
key
is
released,
the
trigger
output
at
the
collector
of
Q8
drops
to
zero,
and
the
sample
and
hold
circuit
no
longer
samples
the
keyboard
voltage.
The
20
millisecond
delay
supplied
by
Q5
and
Q6
is
necessary
to
bypass
the
effect
of
contact
bounce
during
key
depression.
2.3.2
TRIGGERING
{MULTIPLE)
IC6
becomes
important
when
two
keys
are
de
pressed.
Any
abrupt
change
in
voltage
at
the
output
of
IC4
is
applied
through
R66
and
C10
to
the
input
of
IC6.
Cll
filters
out
spikes
less
than
1
millisecond
that
are
associated
with
contact
bounce
or
spurious
interference.
The
resulting
rounded
pulse
is
amplified
by
IC6
(detail
G,
Figure
2-1).
Whenever
the
keyboard
buss
voltage
increases,
the
output
of
IC6
goes
positive,
D9
conducts
and
fires
Q6
producing
a
20
millisecond
positive
going
pulse
at
the
collector
of
Q5.
While
this
20
millisecond
pulse
is
on,
the
trigger
voltage
at
the
collector
of
Q8
drops
to
zero.
Also,
the
collector
of
Q50
drops
to
zero.
This
causes
C13
to
recharge
to
+8.8
volts
at
the
leading
edge
of
the
20
millisecond
pulse
and
resets
the
contour
generators
which
are
described
later.
Thus,
when
a
key
is
held
down
and
a
higher
key
is
depressed,
the
keyboard
sample
and
hold
circuit
again
samples
and
the
trigger
is
reset
momentarily.
The
same
happens
when
a
higher
key
is
released
while
a
lower
key
is
being
held
16
DETAIL
A
IC 4 OUTPUT
KEYBOARD
CONTROL
VOLTAGE
~+7V
+4.5V
OV
-4.5V
I—1ST
KEY
DOWN
t2ND
KEY
DOWN
1ST
KEY-]
JD
KEY
UP—I
up
DETAIL
B
IC 5 OUTPUT
DC
KEYBOARD
DETECTOR
+7V
OV
-16V
DETAIL
C
05
COLLECTOR
TRIGGER
PULSE
+9V
OV
-7V
-12V
■20
MSEC
DETAIL
D
08
COLLECTOR
DC
TRIGGER
+9V
OV
20
MSEC
DETAIL
E
Q4
BASE
KEYBOARD
SAMPLE
AND
HOLD
DRIVE
+8V
DETAIL
F
SOURCE OF
Q51
SAMPLED
KEYBOARD
CONTROL
VOLTAGE
+4.5V
OV
-4.5V
PREVIOUS
NOTE
DETAIL
G
OUTPUT
OF
IC
6
AC
KEY
DOWN
DETECTOR
+8V
+
1.5V
OV
-1.5V
-8V
-I
I*—
1.5
MSEC
1.5V
MIN
(FOR
ADJACENT
SEMITONES)
\r
FIG
URE
2-1
KE
YBOA
RD
TRIGGER
VOL
TA
GE
WA
VEFORMS
17
down
since
Q6
is
fired
by
the
negative
going
output
pulse
of
IC5
coupled
via
C9,
R192,
R78
and
D10.
However,
if
the
higher
key
is
held
and
the
lower
key
is
depressed
or
released,
nothing
will
happen
since
the
keyboard
buss
voltage
remains
constant.
When
all
keys
are
released,
D9
conducts
and a 20
millisecond
pulse
appears
at
the
collector
of
Q5.
However,
the
output
of
IC5
goes
negative,
so
that
when
the
collector
of
Q5
again
goes
negative,
Q8
is
not
reset.
2.3.3
KEYBOARD
CONTROL VOLTAGE
IC3
is a voltage
follower
whose
output
is
the
voltage
of
the
last
key
depressed.
Variable
resistor
R12
controls
the
glide
rate
and
is
connected
between
pins
A7
and
A24.
The
time
constant
of
this
resistor
and
C4
determines
the
glide
rate.
IC9
and
Q2
comprise
another
voltage
follower.
The
difference
between
this
voltage
follower
and
IC3
is
the
amount
of
input
current
required.
IC9
is
biased
at a low
current
level
so
that
input
current
does
not
result
in
a
pitch
error
when
the
glide
rate
potentiometer
is
at
its
maximum
resistance.
The
voltage
at
the
emitter
of
Q2
determines
the
pitch
of the
audio
oscillators
and
is
also
applied
to
the
filters
and
contour
generators
so
that
as
the
keyboard
voltage
goes
up, the
filter
frequency
also
goes
up
and
the
contour
time
constants
decrease.
2.4
OSCILLATOR
IC8
is a dc
summer
adding
pitch,
one-octave
transpose
voltage,
a
tuning
voltage
from
the
fine
tuning
potentiometer
on
the
rear
panel,
a
modulating
voltage
and
the
voltage
from
the
touch
sensor.
R14
is a temperature
compensating
feedback
resistor.
The
summation
constant
increases
with
a
temperature
coefficient
of
approximately
3400
parts
per
million.
The
relationship
between
R14
and
the
input
resistors
is
such
that
the
output
of
IC8
decreases
approximately
20
millivolts
for
each
octave
increase
in
frequency.
2.4.1
OSCILLATOR
A
The
oscillator
A
audio
sawtooth
waveform
is
generated
by
linearly
discharging
C38
through
one
of
the
transistors
in
IC11,
then
rapidly
recharging
it
through
Q45.
The
current
discharging
C38
is
determined
by
the
voltage
difference
between
pins
2
and 4 of
IC11.
The
ratio
of
currents
through
these
two
transistors
in
IC11
is
an
exponential
function
of
the
voltage
difference
between
their
bases.
The
current
fed
into
pin 1 of
IC11
is
kept
constant
by
IC21
which
maintains
the
voltage
at
pin 1 at
the reference
voltage
appearing
at
the
junction
of
R28
and
R29.
It
ac
complishes
this
via
current
feedback
to
pin 3 of
IC11.
The
overall
effect
is
that
C38
discharge
current
doubles
(increases
1
octave)
for
each
20
mv
increase
across
pins 2 and 4 of
IC11.
When 2 OCT
switch
is
up,
R30
conducts
and
Q49
is
saturated,
effectively
placing
the
series
combination
of
R20
and
R21
in
parallel
with
R19.
The
current
at
pin 1 of
IC11
is
then
de
termined
by
the current
flowing
through
parallel
resistors
R19
and
R20/R21.
When 2 OCT
switch
is
down,
R30
does
not
conduct,
Q49
is
open,
and
R20/
R21
are
out
of
the
circuit.
Thus
the
current
flowing
into
pin 1 of
IC11
is
25
percent
as
much
when
Q49
is
open
as
it
is
when
it
is
saturated
and,
for
the
same
voltage
difference
between
the
bases,
the
current
flowing
into
pin 5 is
also
25
percent
as
much.
The
lower
end
of
C38
is
applied
to
low-input-
bias-current
voltage
follower
IC12/Q46.
The
voltage
at
the
emitter
of
Q46
is
applied
to
Schmitt
trigger
Q43
and
Q44.
The
Schmitt
trigger
has a high
hysteresis
factor
and
when
the
voltage
descends
to
the
point
where
the
Schmitt
trigger
fires,
Q45
is
turned
on
and
C38
is
rapidly
recharged.
The
Schmitt
trigger
begins
to
shut
off
when
the
recharge
is
approximately
66
percent
complete.
Because
of
the
storage
time
of
Q44
and
Q45,
C38
is
fully
recharged
before
Q45
is
completely
off.
2.4.2
OSCILLATOR A WAVESHAPING
The
sawtooth
wave
developed
at
the
emitter
of
Q46
(Figure
2-2)
is
applied
through
R41
to
the
base
of
Q47
and
through
R43
to
the
collector
of
Q48.
The
width
of
the
rectangular
wave
that
appears
at
the
collector
of high
gain
amplifier
Q47
depends
on
the
bias
current
supplied
through
R45
from
the
output
FIGURE
2-2
EMITTER
OF
Q46
18
of
IC13.
The
control
current applied
to
the
input
of
IC13
from
the
resistor
matrix
determines
the
out
put
voltage
of
IC13.
When
the
control
current
is
zero,
Q47
remains
saturated
throughout
the
entire
sawtooth
cycle.
Q48
is
also
biased
by
IC13
(via
R118)
and
remains
shut
off
and
as a result,
the
output
voltage
is
the
undistorted
sawtooth.
As
the
control
current
increases,
the
voltage
at
the
output
of
IC13
goes
negative.
When
it is
approximately
-1
volt,
the
current
through
R118
is
sufficient
to
completely
saturate
Q48
and
effectively
short
out
the
sawtooth
waves.
When
it
is
approximately
-3
volts,
Q47
begins
to
conduct
on
part
of
the
sawtooth
cycle
and a narrow
rectangular
waveform
appears
at
its
collector.
When
the
voltage
at
the
output
of
IC13
is
approximately
-9
volts,
the
clipping
of
Q47
is
symmetrical
and a square
wave
appears
at
its
collector.
Thus,
the
waveform
at
the
junction
of
R119
and
R44
is
first
a
sawtooth
when
the
control
current
into
IC13
is
zero,
then
changes
to a narrow
rectangular,
then
to a broad
rectangular,
and
finally
to a square
wave
as
the
control
current
is
increased.
This
waveform
is
applied
to
the
band
pass
filter
via
an
attenuator
network
associated
with
oscillator
board
No. 5 (oscillator
B).
2.4.3
OSCILLATOR B (Minitmoog
Only)
The
circuitry
for
the
second
oscillator
is
located
on
oscillator
board
No. 5 and
consists
of a
current
source
network,
sawtooth
oscillator
and a mixing
network
for
combining
the A and B oscillator
tones.
The
sawtooth
waveform
is
produced
by
charging
C503
through
line P and
discharging
it
by
turning
on
Q501.
The
current
through
line P is
supplied
from
one
of
the
transistors
in
IC11
on
the
main
board.
This
particular
transistor
is
located
on
the
same
chip
with
the
current
source
transistor
for
oscillator
A
and
its
characteristics
are
very
close
to
those
of
the
oscillator
A
current
source.
As a result,
the
ratio
of
oscillator
A
to
oscillator
B
currents
will
be
fairly
constant
as
the
instrument's
pitch
is
varied.
Resistors
R501
thru
R510
supply a relatively
small
voltage
change
at
pin M to
vary
the
ratio
between
oscillator
currents
by a factor
of
4.
Oscillator
B
range
trimpot
R504
sets
the
center
value
of
oscillator
B
pitch.
When
pin T is
grounded
by
the
f
SYNC
tab
switch,
the
"B"
PITCH
control
moves
oscillator
B
pitch
up
and
down
an
octave
relative
to
oscillator
A.
When
pin V is
grounded
by
the
SYNC
tab
switch,
the
aB"
PITCH
control
sweeps
the
natural
frequency
of
oscillator
B
over a range
of
more
than
four
octaves.
In
this
case,
R505
shifts
the
pitch
of
oscillator
B
such
that
oscillators
A
and B are
approximately
in
unison
when
the
"B"
PITCH
control
is
fully
counterclockwise.
Note
that
the
"B"
PITCH
control
is
centertapped
with a center
deadband
to
allow
the
musician
to
quickly
and
precisely
set
oscillator
B
pitch
in
unison
with
oscillator
A.
Octave
trimpot
R510
is
set
so
that
the
pitch
of
oscillator
B
is
either
an
octave
above
or
below
that
of
oscillator
A
when
the
"B"
PITCH
control
is
at
either
end
of
its
rotation.
The
oscillator
circuitry
consists
of
IC501,
IC502
and
Q501
with
related
circuitry.
Q502
and
Q503
are
active
only
when
oscillator
B
is
synchron
ized
to
oscillator
A. A positive
going
pulse
is
produced
at
the
output
of
Schmitt
trigger
IC502
when
the
output
voltage
of
integrator
IC501
surpasses
the
threshold
voltage
at
the
junction
of
R514
and
R531.
Q501
is
turned
on
for
approximately
10
microseconds.
Trimpot
R511
increases
the
frequency
at
high charging
currents
and
is
used
as
a
high
end
tuning
adjustment.
The
sawtooth
waveform
appears
at
the
output
of
IC501.
Sync
pulses
from
oscillator
A
are
applied
at
pin
R
to
the
base
of
Q502.
When
+9
volts
are
connected
to
pin Q by
the
SYNC
tab
switch,
Q502
is
always
saturated.
When
pin Q is
grounded
by
the
SYNC
tab
switch,
the
sync
pulses
turn
Q502
off
and
Q503
on
once
for
every
cycle
of
oscillator
A.
When
Q503
conducts,
the
threshold
of
IC502
drops
to
0 and
the
oscillator
B
waveform
starts
over
(Figure
2-3).
Resistors
R522
thru
R525
form
the
mixing
network.
The
A/B
MIX
control
on
the
front
panel
FIGURE
2-3
SYNCH
RON
IZA
TION
OF
OSCIL
LA
TOR
B
TO
OSCILLATOR
A
19
shunts
varying
proportions
of
oscillators
A
and B to
ground.
The
values
of
resistors
R522
thru
R525
relative
to
the
value
of
the
A/B
MIX
control
are
set
so
that
the
signal
power
sum
at
pins Z and
ZZ
tends
to
remain
constant
as
the
A/B
MIX
control
is
rotated.
The
output
at
pin Z is
the
oscillator
A
signal
applied
to
the
normal
input
portion
of
the
band
pass
filter
via
R122
and
R124.
The
output
at
pin
ZZ
is
the
oscillator
B
signal
applied
further
down
the
chain
of
the
band
pass
filter
to
produce
a
different
sound
character.
2.5
BAND
PASS
FILTER
The
band
pass
filter
consists
of
IC15,
IC16
and
IC17
with
associated
components.
IC16
and
IC17
are
identical
integrators
effectively
connected
in
series
and
their
gains
determine
the
center
frequency
of
the
band
pass
filter
while
the
gain
of
IC15
determines
the
bandwidth
(Q).
These
gains
are
set
by
bias
currents
applied
from
transistor
pairs
Q39/Q40
and
Q37/Q38,
respectively.
These
transistor
pairs
may
be
compared
directly
to
the
transistor
pair
in
ICll
which
determines
the
frequency
of
oscillation.
The
main
difference
is
that
relatively
constant
currents
are
fed
to
these
transistor
pairs
through
R133
and
R129. A precise,
wide
range
relationship
between
output
current
and
base-to-base
voltage
is
not
required
of
these
transistor
pairs.
Only
reasonable
repeatability
and
the
rough
approximation
of
exponential
characteristics
are
required.
2.5.1
BAND
PASS
FILTER
CONTROL
INPUTS
The
bandwidth
is
determined
by
the
voltage
difference
between
the
bases
of
Q37
and
Q38.
The
voltage
at
the
base of
Q37
is
the
result
of
the
band
width
control current
flowing
through
R128.
An
increase
of
18.5
mv
doubles
the
bandwidth.
The
one
source of
bandwidth
control current
is
column
8
of
the
resistor
matrix.
The
center
frequency
is
deter
mined
by
the
voltage
difference
between
the
bases
of
Q39
and
Q40.
The
voltage
at
the
base
of
Q40
is
the
result
of the center
frequency
control
currents
flowing
through
R134.
An
increase
of
18.5
mv
doubles
the
center
frequency.
The
currents
come
from
column
7
of
the
resistor
matrix,
the
BRIGHTNESS
potentiometer
voltage
applied
to
R193,
the
FILTER
CONTROL
INPUT
jack
voltage
applied
to
R184,the
modulation
voltage
applied
to
R181,
the
filter
contour
voltage
applied
to
R116
and
the
keyboard
pitch
voltage
applied
through
R179
and
R180.
The
current
from
column 4 of
the
resistor
matrix
deter
mines
whether
or
not
Q25
conducts.
When
Q25
conducts,
it
becomes
saturated
and
shorts
out
the
keyboard
voltage
controlling
the
center
frequency.
R130
and
R132
are
offset
adjustments
for
setting
correct
values
of
bandwidth and
center
frequency,
respectively
and
compensate
for
transistor
offset
voltages,
resistor
variations
and
gain
variations
of
IC15,
IC16
and
IC17.
2.6
LOW
PASS
FILTER
The
output
of
the
band
pass
filter
is
taken
from
the
source
of
Q41
and
applied
across
the
bases
of
the
bottom
transistor
pair
of
IC19.
This
transistor
pair
and
the
two
immediately
following
it
constitute
a
low
pass
filter
whose
cutoff
frequency
is
proportional
to
the
standing
current.
This
current
is
determined
by
the
voltage
difference
between
pin
13
(ground)
of
IC19
and
the
base
of
Q33.
The
voltage
at
the
base
of
Q33
is
the
result
of
cutoff
frequency
currents
flowing
through
R151.
These
currents
come
from
column
9
of
the
resistor
matrix,
the
BRIGHTNESS
potentiom
eter
voltage
applied
to
R186,
FILTER
CONTROL
INPUT
jack
voltage
applied
to
R185,
modulation
voltage
applied
to
R187
and
filter
contour
voltage
applied
through
R117.
The
setting
of
R139
deter
mines
the
calibration
current
through
R140.
An
increase
of
approximately
18.5
mv
at
the
base
of
Q33
results
in a one
octave
increase
in
the cutoff
frequency
of
the
low
pass
filter.
2.7
VOLTAGE
CONTROLLED
AMPLIFIER
The
transistor
pair
with
common
emitters
on
pin
3
of
IC20
controls
the
amplitude
of
the
audio
wave
form by
variable
transconductance.
The
current
which
determines
this
transconductance
is
determined
by
the
voltage
at
pin
12
of
IC20
and
the
resistance
between
pin
13
and
ground.
The
voltage
applied
to
pin
12
is
the
amplitude
contour
voltage
and
the
resistance
from
pin
B19
to
ground
is
the
100K
VOLUME
control
potentiometer.
IC22
is a differential
amplifier,
the
output
of
which
is
the
final
audio
waveform.
20
2.8
AMPLITUDE
CONTOUR
GENERATOR
Of
the
two
contour
generators,
the
amplitude
contour
generator
is
the
simplest,
so
it
will
be
described
first.
This
contour
generator
consists
of
Q34,
Q35,
Q36,
IC18,
transistor pairs
Q26/Q27
and
Q28/Q29,
Q30,
Q31,
Q32
and
associated
circuitry.
When
the
leading
edge
of
the
trigger
occurs,
Q35
partially
charges
C25
so
that
the
emitter
of
Q35
rises
to
approximately
3.5
volts.
If
Q36
is
saturated,
Q34
does
not
conduct
at
all.
Column 3 of the
resistor
matrix
determines
whether
or
not
Q36
is
turned
on.
If
Q34
is
not
turned
on,
C25
is
free
to
immediately
begin
linearly
discharging
through
Q26.
The
dis
charging
current
from
Q26
is
determined
by
the
voltage
control
developed
across
R189.
If
Q36
is
off,
Q34
holds
the
voltage
at
+3.5
volts
until
the
end
of
the
dc
trigger
occurs
(detail
D,
Figure
2-1).
Thus,
the
voltage
at
the
emitter
of
Q35
is
as
shown
in
Figure
2-4.
The
rise
time
of the
voltage
at
the
emitter
of
Q35
is
determined
only
by
the
ability
of
Q35
to
discharge
C25.
Typically,
this
rise
time
is
less
than 1 millisecond.
The
decay
time
of
the
amplitude
contour
is
determined
by
the
voltage
difference
between
the
bases
of
Q26
and
Q27.
The
voltage
across
R189
results
from
the
amplitude
contour
decay
time
control
currents
coming
from
column 2 of
the
resistor
matrix,
the
keyboard
voltage
applied
to
R199
and
the
shaping
current
from
R169
and
R171.
R190
corrects
for
transistor
offsets
and
other
normal
component
variations.
A
voltage
increase
of
18.5
mv
at
the
base
of
Q26
cuts
the
decay
time
in
half.
IC18,
C35
and
Q32
comprise
a
voltage
follower
whose
slew
rate
is
proportional
to
the
bias
cur
rent
of
IC18.
This
bias
current
applied
from
the
collector
of
Q28
is
determined
by
the
voltage
difference
between
the
bases of
Q28
and
Q29.
Thus,
since
the
decay
time
of
an
envelope
is
generally
longer
than
the
attack
time,
the
voltage
appearing
at
the
source
of
Q32
has
an
attack
time
inversely
proportional
to
the
collector
current
of
Q26.
The
contributions to
attack
time
control
are
similar
to
those
of
decay
time
control.
The
quick-set
current
comes
from
column 1 of
the
resistor
matrix.
Since
Q26
is a nearly
ideal
current
source,
the
decay
slope
at
the
source
of
Q32
would
be a straight
line
if
not
for
the
action
of
Q30.
At
the
beginning
of
the
decay
slope,
the
voltage
at
the
base
of
Q30
is
more
positive
than
the
emitter,
and
Q30
does
not
conduct.
When
the
base
of
Q30
approaches
-0.6
volt
(i.e.,
when
source
of
Q32
is
equal
to
+1.8
volts),
Q30
acts
as
an
emitter
follower
and
the
cur
rent
through
R169
flows
to
R189
and
slows
down
the
decay
slope.
The
more
negative
the
base
of
Q30
goes,
the
higher
its
control
current
and
the
more
the
decay
slope
decreases.
This
gives
the
decay
slope
an
extended
tail
and
therefore
sounds
like a more
natural
exponential
decay.
(See
Figure
2-5.)
When
the
voltage
at
pin
B21
is
+9
volts,
Q31
is
saturated
and
very
little
current
flows
through
R171.
When
the
voltage
at
pin
B21
is
zero,
Q31
is
open
and
current
flows
through
R170
and
R171
to
greatly
speed
up
the
decay
slope.
The
SUST
tab
switch
connects
pin
B21
to
+9
volts
when
it
is
down
and
to
the
trigger
line
when
it
is
up.
As a result,
the
tone
is
rapidly
squelched
when
the
SUST
tab
switch
is
up
and
the
keys
are
released.
As
noted
previously,
the
keyboard
pitch
voltage
controls
both
attack
and
decay
times
through
R199
and
R198,
respectively.
These
times
change
by a factor
of
approximately
2.5
over
the
complete
keyboard
range.
KEY
DOWN
035
EMITTER
(Q36OFF)
OV
-0.6
V
+3.5V—
Q35
EMITTER
(Q36
ON)
0V
-0.6V
=f
r
KEY
UP
FIGURE
2-4
EMITTER
VOL
TAGE
OF
Q35
+3.5V
Q32
SOURCE
(Q36OFF)
0V
-0.6V
+3.5V-
032
SOURCE
(Q36
ON)
OV
-0.6
V
h-KEYDOWNh—
KEY
UP
FIGURE
25
SOURCE
VOL
TAGE
OF
Q32
21
2.9
FILTER
CONTOUR
GENERATOR
The
filter
contour
generator
contains
most
of the
features
of
the
amplitude
contour
generator.
Q15
of
the
filter
contour
generator
corresponds
to
Q35
of
the
amplitude
contour
generator,
Q13
to
Q34
and
Q12
to
Q36.
The
filter
decay
mode
control
voltage
from
matrix
column
11
through
R88
and
R91
determines
whether
the
filter
contour
will
rise
and
then
immediately
fall
or
fall
only
upon
release
of
all
keys.
Q9
and
Q10
of
the
filter
contour
generator
corresponds
to
Q26
and
Q27
of
the
amplitude
contour
generator.
The
current
from
Q10
determines
the
decay
time
of
the
contour.
Similarly,
IC14
corresponds
to
IC18,
Q18/Q19
corresponds
to
Q28/Q29
and
Q16
corresponds
to
Q30.
R95
and
R101
couple
the
key
board
voltage
to
the
attack
and decay
control
circuits.
The
voltage
applied
to
pin
B18
from
the
ATTACK
potentiometer
varies
the
attack
time
of
the
filter
contour.
The
voltage
applied
to
pin
813
from
the
DECAY
potentiometer
varies
the
decay
time
of
the
filter
contour.
Q22
and
Q23
are
routing
switches
and
only
one
is
on
at a time.
The
filter
contour
routing
control
voltage
from
matrix
column 5 determines
whether
Q17
is
open
or
saturated.
If
Q17
is
open,
then
Q21
is
also
open
and
Q24
is
saturated.
Thus,
Q22
is
biased
on
and
Q23
is
biased
off
and
the
contour
is
routed
to
the
low
pass
filter.
On
the
other
hand
if
Q17
is
saturated,
Q23
is
biased
on
and
the
contour
is
routed
to
the
center
frequency
control
input of the
band
pass
filter.
2.10
MODULATION
OSCILLATOR
The
modulation
oscillator
is
mounted
on
power
supply
board
No. 2 along
with
seven
slide
potentiom
eters
and
consists
of
Schmitt
trigger
IC1 and
integrator
IC2
with
their
associated
components.
The
output
of
IC2
is a triangular
waveform
and
the
output
of
IC1
is
a
square
wave.
The
current
supplying
integrator
IC2,
and
therefore
the
oscillator
frequency,
is
varied
over
the
frequency
range
of 1 to
50
Hz
by
RATE
control
RIO.
2.11
TOUCH
SENSOR
2.11.1
MECHANISM
The
touch
sensor
mechanism,
mounted
under
neath
the keys,
has a 20
inch
long
anodized
aluminum
rod
on
which a key
bears
when
it
is
fully
down
(bottomed).
Excess
key
pressure
forces
the
rod
to
compress
its
foam
rubber
support
pad
causing
the
rod
to
come
into
more
intimate
contact
with
the
grounded
conductive
nylon
strip
glued
to
the
foam
rubber
pad.
The
assembly
functions
as a variable
capacitor
and
the
more
force
with
which
one
holds
a
key
down,
the
greater
the
capacitance.
The
touch
sensor
circuit
on
board
No. 4 senses
this
capacitance
increase
and
produces
a
dc
control
voltage
ranging
from 0 (no
excess
pressure)
to
.+6
volts
(maximum
pressure).
2.11.2
VARIABLE
FILTER
AND
AVERAGE
VALUE
DETECTOR
Multivibrator
IC401,
located
on
touch
sensor
board
No.
4,
produces
a
square
wave
at a nominal
frequency
of
100
KHz.
The
touch
sensor
element
is a variable
capacitance
(C410)
connected
across
pin E and
ground.
C410
and
R402
form a variable
low
pass
filter
wherein
the
peak-to-peak
voltage
at
pin E decreases
as
the
value
of
variable
capacitor
C410
increases.
C402
couples
the
waveform
to
clamp
CR401.
The
dc
component
of
the
signal
appearing
at
CR401
becomes
less
negative
as
the
touch
sensor's
capacitance
is
increased.
R403
and
C403
filter
out
the
ac
components
leaving
only
the
dc
component
of
the
signal
to
be
applied
to
emitter
follower
Q401.
R404
at
the
emitter
of
.Q401
and
C404
provide
additional
filtering
of
the
output
signal.
2.11.3
DC
RESTORER
The
keyboard
circuitry
generates a
trigger
voltage
which
is
applied
to
pin A of
board
No.
4
whenever
a
key
is
depressed.
With
no key
depressed,
this
voltage
is
zero,
Q403
conducts
and
IC402
turns
on.
The
voltage
at
the
junction
of
R404
and
R406
(pin 2 of
IC402)
is
kept
very
close
to
zero
when
the
input
trigger
is
zero
through
a
feedback
loop
consisting
of
Q402
and
R406.
Whenever
any
key
is
depressed,
the
trigger
voltage
at
pin A rises
to
+9
volts
and
Q403
shuts
off,
shutting
off
IC402.
C405
holds
the
voltage
that
existed
before
the
trigger
appeared
and
the
junction
of
R406
and
R404
remains
close
to
zero
until
the
touch
sensor
element
capacitance
increases.
When
the
element's
capacitance
begins
to
increase
22
(as a result
of
pressing
down
harder
upon a key),
the
voltage
at
the
junction
of
R404
and
R406
begins
to
-i$e.
Thus
IC402,
Q402,
Q403
and
related
circuitry
yrnPa
dc
restorer
that
keeps
the
voltage
at
the
junction
of
R404
and
R406
at
zero
until
a
key
is
depressed
and
returns
it
to
zero
when a key
is
released.
2.11.4
AMPLIFIER
The
voltage
at
the
junction
of
R404
and
R406
is
applied
to
open
loop
amplifier
IC403.
The
value
of
R408
is
set
so
that
the
input
of
IC403
begins
to
saturate
when
the
touch
control
output
rises
to
ap
proximately
50
percent
of
its
maximum
value
and
saturates
more
and
more
as
the
touch
sensor
element
is
depressed
further*
This
allows
the
touch
sensor
to
be
more
sensitive
at
the
beginning
of
its
travel
and
to
become
increasingly
less
sensitive
as a key
is
depressed
with
more
force.
The
touch
control
output
at
pin G rises
from
0
to
approximately
+6
volts
and
sweeps
the
filters,
both
oscillators
or
just
the
second,
oscillator
depending
on
how
the
front
panel
touch
sensor
switches
are
set.
2.11.5
MODULATION
AMOUNT
The
touch
control
output
from
pin 6 of
IC403
is
also
applied
through
R411
and
Q404
to
control the
gain
of
IC404.
The
triangular
modulation
wave
is
applied
at
pin H from
the
output
of IC2.
The
modu
lating signal
of
varying
amplitude
at
pin J is
available
for
modulation
when
the
TOUCH
CONTROLS
MOD
tab
switch
is
depressed.
It
should
be
noted
that
the
ratio
between
R412
and
R413
is
set
so
that
C409
rounds
off
the
triangular
wave
to
yield a
desirable
sinusodial
wave
effect.
SECTION
3
DISASSEMBLY,
VISUAL
INSPECTION
AND
REASSEMBLY
3.1
DISASSEMBLY
3.2
VISUAL
INSPECTION
Disassembly
and
inspection
are
essentially
the
same
for
both
Synthesizers
except
where
the
Touch
Sensor
Board 4 and
the
Oscillator
Board 5 are
mentioned.
These
boards
are
used
only
on
the
Minitmoog.
a)
Disconnect
power
cord
connector
and
all
other
rear
panel
connections.
b)
Stand
instrument
on
one
ei.d
and
remove
three
screws
securing
large
bottom
cover
(Figure
3-1)
to
instrument
using a medium
sized
Phillips
head
screwdriver
and
remove
cover.
NOTE
All
internal
alignment
and
adjustment
controls
are
now
accessible.
c)
If
necessary,
the
narrow
bottom
cover
may
be
removed
by
taking
out
an
additional
10
screws.
a)
Inspect
instrument
for
broken
wires,
loose
printed
circuit
boards
or
electrical
connectors,
cable
harness
wires
pushed
into
keyswitches
and
rotary
pots
with
terminals
shorted
to
chassis.
b)
Check
for
frayed
conductive
nylon
on
touch
sensor
assembly
shorting
to
keyboard
switch
assembly.
3.3
PRINTED
CIRCUIT
BOARD
REMOVAL
a)
Main
Board
No. 1 -
Disconnect
5
electrical
connectors,
depress
levers
on 6 fastening
devices
and
remove
board
from
bottom
cover.
(See
Figure
3-1.)
b)
Power
Supply
Board
No. 2 -
Remove 7 slide
knobs,
narrow
bottom
cover, 2 electrical
connectors,
2
screws
and 1 foot
and
carefully
lift
power
supply
from
instrument.
WARNING
Removing
narrow
bottom
cover
exposes
live
terminals
of
the
ac
POWER
tab
switch.
Use
extreme
care
when
power
cord
is
connected
to
primary
power.
WARNING
Removing
narrow
bottom
cover
exposes
live
terminals
of
the
ac
POWER
tab
switch.
Use
extreme
care
when
power
cord
is
connected
to
primary
power.
23
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