LG 42PC55 Service Manual page 27

6. In case of no sound
(1) Symptom
1) LED is Green.
2) Screen display but sound is not output.
(2) Check following
All input(mode) is no
sound?
YES
Only HDMI is No
Sound?
YES
Only RF is no sound?
YES
Only AV/component/PC
input is no sound?
Yes
Only specific input
(except HDMI,DTV,RF)
is no sound?
No
No
Download
the EDID data
No
Check
the Tuner IN/OUT
No
Is the output of
CXA2069 normal?
YES
Check the signal after
CAX2069 refer to circuit diagram
No
Check the signal before
CAX2069 refer to circuit diagram
Is the speaker On it
menu?
Is the speaker Cable
normal?
No
Replace the CXA2069
IC1300 operates
normal?
IC1301 operates
normal?
Replace the VSC B/D
No
Set on speaker in menu.
YES
No
Check the Speaker
Yes
No
Replace the IC1300
YES
No
Replace the IC1300
YES
Cable.
(MSP4450)
(STA335BW)