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IC801 KA9201 (CXA1081)
DEFECT AMP
C806
DEFECT
DEFECT
COMPARATOR
DEFECT
BOTTOM HOLD
RFO
DEFECT
AMP
BOTTOM HOLD (1)
Solid Line CC1
d
BOTTOM
HOLD (2)
Dotted Line CC2
DEFECT
1.44 sec MAX
8. FOCUS SERVO SYSTEM
1C801
KAQg201
(CXA1081)
@ FE
1C802 KA8309 (CXA1082)
TO !1C806
FOCUS
LA6520 CD)
PHASE
(FOCUS
COMPENSA-
ACTUATOR
TION
DRIVER)
R820
100K
+ C826
47/10
C816 =
al
Vret
+5V
The above is a block diagram of the focus servo system. When FS3 is switched on, the high frequency
gain can be reduced by forming a low frequency time constant through a capacitor connected across pins
2 and 3 and the internal resistor.
The capacitor across the pin 10 and GND has a time constant to raise the low frequency usually playback
condition. The peak frequency of the focus phase compensation is inversely proportional to the resistor
connected to pin 17 (about 1.2kHz when the resistor is 510K).
The focus search peak becomes
about +1.1Vp-p with the above constant. The peak is inversely
proportiona! to the resistor connected across the pins 29 and 31. However, when this resistor is varied, the
peaks of track jump and sled kick also vary.
The FZC comparator invert input is set to 2% of the difference between the reference voltage Vcc and VC
(pin 1) : 2% x (Vcc-VC).
-—18-
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