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Moog Satellite Service Manual

Moog Satellite
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"
TJ»
e
positive
‘power
supply
regulator
consists
..
a3S
ociated
components.
This
circuitry
is
completely
.
^
Vl2
ntional.
It
will
deliver
55
or
60
mi
Hi
amperes
before
the
/ojtdge
developed
across
current
sense
resistor
R2
limits
the
Cl
,rrent.
.
/
T
he
negative
regulated
supply
circuit
consists
of
IC2,
Ql,
and
associated
components.
This
circuit
simply
adjusts
its
output
to
be
the
negative
of
the
regulated
+9.
No
current
limiting,
other
than
that
supplied
by
R8,
is
provided.
The
keyboard
circuit
consists
of
IC3,
IC4,
IC5,
IC6,
IC7,
IC9,
IC10,
and
related
circuitry.
The
keyboard
itself
contains
a
string
of
thirty-six
100
ohm
resistors.
The
string
is
connected
between
A5
and
AS.
The
current
through
the
resistor
string
is
regulated
by
IC7
so
that
the
drop
across
R79
and
R80
’
is
excictly
4.5
volts.
R79
is
set
so
that
the
voltage
at
A6
is
exactly
-4.5
volts.
The
voltage
at
the
keyboard
buss
is
fed
to
voltage
follovrer
IC4.
,
Because
of
resistor
R53,
the
keyboard
buss
voltage
rises
to
7
volts
or
so
when
no
key
is
depressed.
The
output
of
voltage
follower
IC4
i|HJien
fed
to
comparator
IC5.
The
output
of
IC5
swings
from
+7
to
-16
volts
whenever
the
input
goes
above
+4.8
volts.
Q5
and
Q6
comprise
a
monostable
multivibrator
that
produces
a.pulse
of
approximately
30
milliseconds
duration
(Fig.
1).
When
the
output
of
IC5
swings
positive,
a
positive
spike
is
fed
through
C7
and
CR7
to
the
base
of
Q6,
initiating
a
2,0
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
rocnostable
(the
collector
of
Q5)
is
negative.
That
is,
Q7
begins
to
conduct
approximately
30
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
goes
from
0
to
+9.
When
this
happens,
C13
discharges
through
R61,
producing
a
ramp
voltage
at
the
base
of
Q4
that
decreases
from
+9.
to
-0.6
in
approximately
20
milliseconds
(Fig.
2)
.
’
Q4
is
an
emitter
follower
that
supplies
a
current
through
R62
and
Q3
to
turn
on
IC10.
IC10
and
Q51
and
associated
circuitry
comprise
a
sample-hold
circuit.
VThen
the
current
ramp
is
fed
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
volts,
the
bias
current
being
fed
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
trickle
bias
current
of
approximately
.50
nanoamperes
flows
through
R59
so
that
IC10
is
capable
of
supplying
a
small
current
to
C5
to
keep
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
3.0
milliseconds
after
the
key
is
depressed,
and
is
brought
to
.
*
be
equal
to
the
new
key
voltage
well
before
the
ramp
current
turning
IC1G
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

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Moog Satellite Specifications

General IconGeneral
BrandMoog
ModelSatellite
CategorySynthesizer
LanguageEnglish

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