LG GDR-8161B Service Manual page 6

IC201
1. Structure of the Pick-up
SF-HD66 is consist of monitor diode for DVD laser and CD laser.
When DVD laser is ON, PG101 20 Pin is need to connect GND for getting monitor voltage.(PG101 22 pin).
When CD laser is ON, PG101 19 Pin is need to connect GND for getting monitor voltage.(PG101 22 pin).
This control is done by handling Q102,Q104 from CD signal (IC201 175 pin output).
14
175
CD
CD: Hi
DVD: Lo
Q102,Q104
Monitor resister SW circuit
For CD For DVD
19 20
VRCD VRDVD
19 20
1
SF-HD66
P/U
22
MD
FFC
22
PCB
3
IC101