LG LH-T6740, Service Manual

Page: 31 / 57

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D
C
YES
NO
YES
YES
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.
YES
YES
NO
NO
Laser turns on when
reading disc? NO
NO
YES
NO
YES
YES
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