LG GDR-8161B Service Manual page 18

3-6. TRACKING SERVO SYSTEM
TE
A/D
111
LNSC
A/D
113
Tracking servo is used to follow trace center of detector with TE signal and to control stepping motor.
Tracking servo make lens into center of detector using LNCS signal.
TE signal is sampled by A/D converter during sequential read and do gain compensation, phase compensation
in parallel digital compensator.
This signal is changed to analog signal in D/A converter and feed into Drive IC301 from IC201 120 pin and
operate tracking actuator.
Control of stepping motor(sled motor) is decided by disk and rotation speed,and control signal output is obtained
by IC201 66 and 67 pin.
If large lens shift,detected lens shift quantity by IC201 pin116 and compensated by u-com.
During long seek,LNSC is converted by A/D and compensated.
Therefore servo is applied good and controlled detector s center.
26
IC201
Parallel
digital
compensator
Sled
Compensator
Quantity of
Lens shift
Controlled by
prediction and
lens shift quantity.
Tracking servo system
TD
D/A
120
PWM
55
TRS
A/D
116
66
PWM
67
IC301
(Drive IC)
Lens control
3.3V
SIN1
IC301
(Drive IC)
SIN2
To control
stepping motor