LG DP122NU Service Manual page 29

ELECTRICAL TROUBLESHOOTING GUIDE
C
Laser
NO
turns on when
reading disc?
YES
NO
Put disc in?
YES
NO
Disc ID
is correct?
YES
NO
Does
spindle rotate?
YES
D
DVDLDO,
CDLDO output
properly?
YES
Collector
voltage of power
transistor is OK?
YES
Check cable connection
between transistor ouput
and pick-up head.
Laser off
Proper PUHRF
signal on OPU
YES
Check DVDLDO &
CDLDO signal
Proper
SCO signal on
SPHE8202RQ-D
YES
SLED+
& SLED- output
properly?
YES
Check the cable
connection between
spindle and main PCBA.
3-16
Check the laser power
NO
circuit on SPHE8202RQ-D and
connedting to power transistor.
NO
Check the related circuit on
laser power transistor
NO
Check the related circuit
on PUHRF signal.
NO
Check SCO related
circuit on SPHE8202RQ-D.
NO
Check the spindle control
amp circuit of motor driver