Roland SYSTEM 100 101 Service Notes page 8

1976-7-30
SYSTEM 100-101
2-3.
VGA
is
a
voltage controlled amplifier,
having
its
gain
controlled
by the voltage supplied
from
ADSR, LFO
and
applied on
its
current source
transistor.
2-4
Envelope Generator produces
the
ADSR
triggered
by
the
keyboard gate voltage, the positions of the four sliders
in
the
ADSR
section
determine the steepness of the curves of each section and
level of
the envelope.
2-5.
Noise Generator
is
using, as
its
sound
source,
white
noise
appearing
upon
the junction of the reverse biased
transistor,
and on
use,
by further amplifying such noise.
2-6.
LFO
is
a
low frequency
oscillator
for use of
modulation, with the Sine
Wave, Sawtooth and Square Waves
for
modulation of
VCO,
VCF
and
VGA,
while Triangular
Wave
for Pulse
Width modulation,
2-7.
Flead-Phone Amplifier provides A-class
amplified
signals
through
its
output transformer.
2-8.
Mixing Amplifier mixes
the signals
from
VGA
with that of
A-440
FIz
Standard
Oscillator,
thus providing the
output of the
mixed
signals
from
here.
3.
A-440
HZ OSC
BOARD ASSEMBLY
(OP-30)
This
circuit
is
a
very stable
LG
Oscillator.
4.
POWER
SUPPLY
BOARD ASSEMBLY
(OP-22,
OP-24)
The assembly
is
a
voltage regulator circuit,
to provide the
constant voltages of -I-14V
and
—14V,
and
in
order to
assure of such precise voltage an adjustable
trimmer potentiometer
is
incorporated
.
Note:
The
board PS-22
is
for
1
0OV
-
200V,
while
PS-24
for
220V
-
240V.
Fuse 0.5A, Fuse
Flolder
TF-758,
of Label
No.
69,
are to
be used
on PS-24
alone.
For
PS-22, use
such ones having
jumper
wire
on Fuse
Holder.
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