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9. TRACKING SERVO SYSTEM
2
IC802 KA8309
ae
e710
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-5V
tc
4
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TZC
46)
n
9) 1SET G0) 3.5V
R816
ce
100K
ae
8)
TO LIMIT
C812
Ae
ATSC il
~ U 100K
Pe
—_
0.0022
47)—O
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se
R815
arse
'
6.8K
TO IC806
s
:
(4)
SLO
LA6520 @)
100K
zak
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pee
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(15)
R834
C833
TM6
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6)
33K ,
_ 10/16
(CXA1081)
(13)
2
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—=MS
22 2A
10K
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6
R814
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270K
Vret
aa
(2)
ooo
TO IC806
LA6520
(TRACKING
ACTUATOR
DRIVER)
+5V
The above is a block diagram of the tracking sled servo system.
The capacitor across pins 8 and 9 has a time constant to lower the high frequency when TG2 is switched
off. The tracking phase compensation peak frequency is inversely proportional to the resistor connected to
pin 17 (about 1.2kHz when the resistor is 510K).
For a tracking jump in the FWD or REV direction, TM3 or TM4 are set to ON. At this time, the peak voltage
fed to the tracking coil is determined by the TM3 and TM4 current values and the feedback resistor from
pin 12.
That is :
Track jump peak voltage=TM3 (TM4) current value x feedback resistor value
The FWD or REV sled kick is done by setting TM5 or TM6 to ON. At this time, the peak voltage added to
the sled motor is determined by the TM5 or TM6 current value and the feedback resistor from pin 15.
Sled jump peak voltage=TM5 (TM6) current value x feedback resistor value
Each SW current value is determined by the resistor connected to pins 29 and 31.
Wheti the resistor is at about 120K2.
TMS or TM4 is +112A and TM5 or TMG is +22zA.
This current value is almost inversely proportional to the resistor, variable within a range of about 5 to
404A for TMS.
S STOP is the ON/OFF detection signal for the limit SW of the sled motor's innermost circumference.
—19-
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