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CX-683
1.2 SIGNAL PROCESSOR BLOCK (CXD2655BR IC201)
1.2.1 SERVO BLOCK
1) Servo Block
This block offers servo control over the focus, tracking, spindle and carriage.
FE, TE and SE signals from the amplifier are A/D converted, equalized on D.F (digital filer) block, and then output to
PWM.
The spindle servo detects phase and frequency of input signal (from 55 pin RFI terminal for Pre_disc and 78 pin ADFG
terminal for Rec_disc), then outputs it to PWM via the filter.
These signals are power amplified on the driver IC401 to drive the actuator and motor.
Focus Servo System
In order to close the focus, the actuator is driven up near to the Disc once, then moved down.
As soon as up-move is started, the spindle is kicked for 252 ms, then ofst drive is turned on.
Focus close is carried out when the following conditions are met:
1) The actuator, after having approached the Disc once, is now moving away from it.
2) FOK = H (Can be monitored on the mnt0 terminal when the mnt selector is set to 00.)
3) FZC = ↑
After the focus close has been started, the microcomputer judges the operation is complete if FOK = H continues for 32 ms.
Pick up
FOK
FZC
6
IC101
RF
FE
amplifier
A, B, C, D
IC401
FOP
Driver
FOM
FIN (For monitoring control signal)
FE
close_point
IC201
A/D
EQ
PWM
BIAS
Close operation is judged to have
successfully ended when FOK
remains at "H" for 32 ms.
FFDR 88pin
FRDR 89pin
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