Samsung MAX-485 - Page 27

4) TRACKING SLED SERVO SYSTEM (KA9220) : WICO1
The
diagram
of
Tracking
Sled
Servo
System
is
shown
in
the
following.
The
capacitor
between
pin
15
and
16
has
a
time
constant,
and
lowers
the
high
frequency
when
TG2
is
off.
The
maximum
frequency
of
tracking
phase
compensation
is
inversely
proportional
to
the
resistance
connected
to
pin
7
(about
1.2
KHz
at
470K).
The
tracking
jump
in
the
direction
of
FWD
and
REV
is
decided
when
TM3
and
TM4
are
ON,
and
the
peak
voltage
induced
from
tracking
coil
is
decided
by
the both
TM3
and
TM4
current
values,
and
feed
back
resistance
of
pin
47.
Track jump max. voltage = TM3 (TM4) current x feedback resistance
PHASE
COMPENSATION
0.033UF
FWD or REV sled kick is carried out when TM5 or TM6 is ON, and the peak voltage added to sled motor is decided by
TM5 or TM current and the feedback resistance of pin 41.
Sled jump max. voltage = TM5 (TM6) current x feedback resistance
Each SW current is decided by the resistance connected to pin 22 and 23.
When the resistance is about 150 k 2,
TM3 or TM4 = 11 pA;
TM5 or TM6 = 22 pA.
This current is value is almost inversely proportional to the resistor,variable within a range of about 5 to 40 yA for
TM3.
STOP is the ON/OFF detection signal for the limit SW or the sled motor's innermost circumference.