Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
2-8
NO
NO
NO
Check the laser power circuit
on MT1389/L and connecting
to power transistor.
(Q401, Q402).
YES
YES
YES
YES
YES
YES
Check cable connection
between transistor output and
pick-up head.
Laser off.
Check the RF connection
between AM5890 and MT1389/L.
YES
YES
DVDLD or
CDLD output
property?
NO
Check the related circuit on
laser power transistor.
Collector
voltage of power transistor
is OK?(Q401, Q402)
Laser turns on when
reading disc?
Put disc in?
NO
NO
Check the SPINDLE related
circuit on MT1389/L.
Check the cable connection
between spindle and main
PCB.
YES
YES
Proper
SPINDLE signal on
MT1389/L.
NO
Check the spindle control amp
circuit of motor driver.
SPNP
SPNN output
properly?
Does spindle rotate?
NO
NO
Check the related circuit on
MT1389/L RF signal.
Proper
RF signal on MT1389/L.
Disc ID is correct?
C
D
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