LG GWA-4164B Service Manual page 78

Recognition Fail Case 1:
CD-ROM Fail
Check Pickup Read Power
was 1.3 ~1.7mW?
YES
Does Focus Servo
operate normally?
YES
Check Pickup
RF signal IC121(Pin81)
RFOUT was 2~2.5V?
YES
Check EQOUTP
waveform (IC121 Pin 74) was
1.75~2.3V?
YES
Check after replacing IC201.
It is OK?
YES
OK
Recognition Fail Case2 :
Blank CD-R/RW
Is there WBL (IC121 pin63)
signal?
NO
Replace IC121.
82
NO
Go to "LD CHECK".
NO
Go to "Focus Servo is unstable".
NO
Check the Pick-up FFC and CN101.
Replace the Pick-up.
NO
Replace IC121.
NO
Go to "Tracking Servo is unstable".
YES
Is there WBL (IC201 pin39)
signal?
NO
Check the connection between
IC201 and IC121.
YES
Replace the IC201.