LG CRD-8402B Service Manual page 15

PHOTO DIODE STRUCTURE OF THE PICK-UP
(1) Focus Error Signal –> (A+C)-(B+D)
(Control the Pick-up's up and down to focus on the Disc)
(2) Tracking Error Signal –> (E-F)
(Control the Pick-up's left and right shift to find the track on the Disc)
(3) RF Signal –> (A+B+C+D)
(RF Signal is converted to Data Signal in One Chip IC (IC501))
Three signals (Focus Error Signal, Tracking Error Signal and RF Signal) above are I-V converted and
amplified at the IC102, and then are transmitted to One Chip IC (IC501) to generate the Servo Control
Signal and Data Signal.
B
E
C
Pick-Up module
A
F
D
Tracking
Red laser
Focusing
11