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PR-8210-A
rotation too far at maximum
input level. Since the
required. angle of rotation in the tangential mirror
increases
while moving towards the outer track in
CAV
dises, the gain is switched in 4-step switching
by the 041770418
FET
switch.
With CLV
dises,
the gain
is fixed.
The error signal required
for the
spindle
serve
is obtained
from
the branch
point
between
В 15-4 and В 152, amplified by AMPS.
and
mixed with the PFC output in order to control the
spindle motor
| Lock detector circuit
The
lock detector circuit includes 2 detectors,
one
for detecting à phase difference
of less than
31.Таз
between
REF
H and PB И, and the other
for detecting
a difference
of less than
10и».
The
first is Used 10 switch the tangential servo loop on
and off, while
the other
is obtained as an output
from y
3-е Mirror limiter
When
using
dises of considerable
eccentricity.
the movable
rai
of the mirror
will be initially
rather wide, making lock-in difficult to attain. For
this reason, the voltage from pin 13 which appear
in
the
same
timing
as
tangential
servo
lock
is
applied
to 2408
voltage
comparator,
and passed
€————
Áo
wea
1
ЕС
through the R529 C151 delay circuit, resulting the
Q419 gate voltage is increased gradually. The width
of the mirror hmiter is thus widened gradually.
і.
Spindle Motor Control Circuit
Тһе circuits required for control of the spindle
motor
are
all incorporated
in 2106.
The
major
component
circuits include:
(13 ап ор. amp..
(2) comparator, and
(3) logic circuits.
l-a starting
When
the play key
is pressed.
RUN
from
the
CONT
board
is switched
from H to L level, result-
ing in ST Бети
turned
on. and the +\№ес
output
being
obtained
from
AMP2.
Since the externally
connected
amplifier stage is a non-inverting ampli-
fier,
720V
is applied
to the motor
and the disc
starts to rotate.
Motor rpms are detected by an AC
tacho-generator, and when the rpm reaches 1500, а
1.2% voltage is generated on pin 17. Since the vol-
tage
on
pin
19
is
set
exactly
to
this
voltage,
COMP2
is inverted.
The acceleration drive is then
stopped,
and the 56 loop switch
is turned on.
If
the focus servo has already been locked.
a COMP
SYNC
signal will be passed
from V-DEM.
resulting
ғ
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-
Hot
=
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=
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.
+
AF ~
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.
.
„бек =
=
+
3s
E
5
EEE
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Rub
~
+4
TES
Rot
2.0.
SND
+
а
ae
E
==
dE
ве
а
B e
амр > +
---
ЕРУ
им5оог
2%
3
А
>
-——-
E
[> *
Шетке
Га
=
сом?
n
'
D
i
NUN
S
20МР 3
сомға
COMPS
_—
CEN:
T
SN
+
AS
ڪڪ
Ne
46v
|
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у
we
|
- ——-«]
n
MEE
У
d
Ы
сомен
FEE
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4
F
Aw
BUFFER
E.
ч
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i
%
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:
і
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—
isp -
—
س
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37.
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(an)
6)
ЈА
Е
|
poo
es
С И
а
Fig. 21
Spindle motor control circuit
га
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