LG LH-CX640 Series Service Manual page 64

3-71
D
C
NO
NO NO
Does
spindle
rotate? Proper DMSO
signal on
MT1389
Check
DMSO related
circuit on
MT1389.
SP+ &
SP- output
properly?
Check the
spindle
control
amp
circuit of
motor
driver.
Check the
cable
connection
between
spindle
and main
PCBA.
NO NO
Laser turns on when
reading
disc?
NO NO
NO
NO
LD01 or
LD02 output
properly?
Check the
laser
power
circuit
on
MT1336 and
connecting to
power
transistor.
Collector
voltage
of
power
transistor
is
OK?
Check the
related circuit on
laser
power
transistor
Check
cable
connection
between
transistor ouput and
pick-up
head.
Put
disc in?
Laser
off
Disc
ID is
correct?
Proper
RFL signal
on MT1389?
Check the
related circuit
on
MT1389
RFL
signal.
Check
LDO1 &
LDO2 signal
YES
YES
YES
YES
YES
YES
YES
YES
YES