LG LH-CX640 Series Service Manual page 66

3-73
Normal
IR.VFD
&
Front
pannel key functions?
Communications
between
IR.VFD
Front pannel key &
MT1389
is
normally?
Check
communication
lines
on
MT1389.
NO
YES
Check
the
cable
connection on
Front
pannel.
TEST
END
YES
Normal
Audio
output
when disc
playback?
Audio
DAC
received
correct
data
stream?
Check
connection
between
MT1379
&Audio DAC.
Normal
Audio
DAC
out?
Check
the
related
circuit of
Audio
DAC.
Check
Audio
filter,amplify,mute
circuit.
NO
NO
NO
YES
YES
YES
E
NO