Service
Manual C221 CD
Player
neVox
the nominal speed,
the reverse
action is taken.
The TTMO signal causes an offset in the
control circuit of
the
disc
motor.
lf the inertia measured during the acceleration of the disc motor is
small
(short
starting
time),
the TTMO signal
changes
to
"1".
lf a
large inertia is measured
(long
starting
time), the TTMO signal
remains at
"0".
lf TTMO is
"'1"
the DC
gain
(lC7)
is reduced
and
an
offset is
fed into the speed control
circuit.
4.1.5 Servo
processor
The servo
processor
lC3 which is
only enabled
when the AC
power
is switched on,
controls the
radial
processor
and
the
drawer.
The servo
processor
receives its
commands
from the
microprocessor
on the convefter
board
via the serial SBUS, and
the subcode information
from
the
Q
channel bus of the
demodulator.
The radial control operates
with
a bandwidth of 20 kHz. Among
others the servo
processor
supplies the following signals:
.
SI/RD
-
Servo system focus
ON/OFF
r
SWAB/SSM
-
Subcode word
clock andstar.t/stop
turn
table motor
.
CRI/DODS
-
Drop-put
detector suppression
.
ASTB
-
-12
dB attenuation, software controlled
.
MUSB
-
Digital
filter mute
signal
.
AM
-
Additional
mute
Drawer motor control
The servo
processor
lC3
supplies the TRMOT
signal for the drawer
control.
lC6
amplifies
TRMOT
and
directly controls the drawer
motor.
lf
the
TRMOT output of lC3 is in
the tristate
condition,
the
drawer
motor is
stopped.
lf TRMOT
=
"0"
the motor
opens the drawer, if
TRMOT
=
".1"
it closes
the
drawer.
lf
the
drawer
jams
and cannot move, the
servo
processor
automatically triggers a
timeout.
The DRAWER-POS signal indicates the
disc drawer
position
to
the
servo
processor.
lf the drawer is
in either limit
position
(open
or
closed), the DRAWER-POS signal changes to
"0".
When the
drawer is
in
an
intermediate
position
during the
opening or closing
process,
the DRAWER-POS signal
changes
to "1".
31
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