Samsung MAX-557 - Page 36

4) TRACKING SLED SERVO SYSTEM(KA9220) : NIC9220
The diagram of Tracking Sled Servo System is shown in the following. The capacitor between pin15 and 16 has a
time constant, and lowers the high frequency when TG2 is off. The maximum frequency of tracking phase compen-
sation is inversely proportional to the resistance connected to pin7(about 1.2KHz 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 pin47.
Track jump max. Voltage= TM3(TM4) current x feedback resistance.
ISET VREG
FWD or REV sled kick is carried out when TM5 of TM6 is ON , and the peak voltage added to sled motor is decided by
TM5 or TM current and the feedback resistance of pin no. 41.
Sled jump max. voltage = TM5(TM6) current x feedback resistance.
Each SW current is decided by the resistance connected to pin no.22 and 23.
When the resistance is about 150kQ.
TM3 or TM4 = 11pA;
TM5 or TM6 = 22pA.
This current is value is almost inversely proportional to the resistor, variable within a range of about 5 to 40pA for
TM3.
STOP is the ON/OFF detection signal for the limit SW or the sled motor’s innermost circumference.
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MAX-550