Panasonic PT-40LC12 Service Manual page 30

No sound from built-in both L-CH and
R-CH Speakers
Press "ACTION" button on the Remote Control to display
MENU screen, and select "AUDIO" in MENU screen.
Check if "SPEAKER" in AUDIO MENU is set to "ON."
Check if the Headphone is not connected to PHONES
jack (JK4590) in front of the unit.
Check that there is an audio signal to the Audio Out
Terminal from all input terminals.
Insert the Headphone to the PHONES jack.
Is the sound from the Headphone heard ?
Replace TV Main C.B.A.
No sound from built-in L-CH Speaker only
Press "ACTION" button on the Remote Control and select
"AUDIO" in MENU screen. Then press "AUDIO ADJUST"
Does the "BALANCE" in AUDIO ADJUST screen becomes
center position?
Connect the L-CH speaker connector cable to P4501 on
TV Main C.B.A.
YES
Is the sounds hears from the L-CH speaker?
No sound from built-in R-CH Speaker only
Press "ACTION" button on the Remote Control and select
"AUDIO" in MENU screen. Then press "AUDIO ADJUST"
Does the "BALANCE" in AUDIO ADJUST screen becomes
center position?
Connect the R-CH speaker connector cable to P4503 on
TV Main C.B.A.
YES
Is the sounds hears from the R-CH speaker?
YES
YES
YES
YES
YES
YES
YES
NO
NO
(All input are NG.)
(Only Line1, 2, Component1,
or 2 input is NG.)
(Only Tuner input is NG.)
(Only Line3 or PC input
is NG.)
NO
NO
NO
NO
NO
Select "ON."
Pull out the Headphone from the
PHONES jack.
Replace Rear Jack C.B.A.
Replace Rear Jack C.B.A.
Replace TV Main C.B.A.
Replace Front Jack C.B.A. Still NG,
replace TV Main C.B.A.
Replace Front Jack C.B.A. Still NG,
replace TV Main C.B.A.
Set to the center position.
Replace the L-CH speaker.
Set to the center position.
Replace the R-CH speaker.