Service manual

32
LC-20B8U-S
LC-20B9U-S
LC-20B9U-SM
TROUBLE SHOOTING TABLE (Continued)
No sounds come out.
No sounds come out from the speakers.
Yes
Yes
No
No sounds come out from the monitor output.
Is pin (58) of IC2001 at "L"?
Is the signal of the collector of Q3403 at "L"?
Check the peripheral parts of IC3201.
Yes
Yes
Yes
No
No
No
No
No
Perform checking from Q3403 to pin
(58) of IC2001.
Perform the following checking.
1No TV sounds come out: Check the
peripheral parts of Q3203, Q3204 and
the peripheral parts of TU3401.
2No input 3 sounds come out: Perform
checking from J3403 to pins (2) and (4)
of IC3401.
3No input 4 sounds come out: Perform
checking from J3403 to pins (9) and
(11) of IC3401.
4No input 1 input sounds come out:
Perform checking from J3405 to pins
(46) and (48) of IC3401.
5No input 2 sounds come out: Perform
checking from J3405 to pins (22) and
(24) of IC3401.
6No PC input sounds come out: Perform
checking from J3409 to pins (47) and
(48) of IC3201.
Check Q3403, Q3401 and Q3402.
Yes
No
Check the input line and its
peripheral parts.
Is pin (43) of IC2001 at "L"?
Yes
No
No
Perform checking from Q3413 to
pin (43) of IC2001.
Yes
Check J3403 and its peripheral parts.
Yes
Check the peripheral parts of IC3404.
Do all the input modes (TV, Input 1~4) fail to
produce sounds?
Perform the following checking.
1
Is the monitor output set to "Sound Fixed" or
"Sound Variable"?
2
Is the sound volume level sufficient?
3
Is the muting effect turned off?
4
Are the headphones disconnected?
Do the following.
1
Set the monitor output to "Sound
Fixed".
2
Raise the sound volume level.
3
Turn off the muting effect.
4
Disconnect the headphones.
Perform the following checking.
1
Do sounds come out from the speakers?
2
Is the monitor output connected properly?
3
Is the muting effect turned off?
Is the audio signal outputted from pins (36) (Rch)
and (37) (Lch) of IC3201?
Do the following.
1
Perform checking according to the
steps under "No sounds come out
from the speakers".
2
Connect the monitor output
properly.
3
Turn off the muting effect.
Are the inputs at pins (2) and (12) of IC3404 as
specified?
Are the outputs at pins (14) and (15) of IC3404 as
specified?
No
Yes
No
Yes
Yes
No
Is pin (53) of IC2001 at
“L”?
Muting effect is on. Check the SP
MUTE line.
Are input and output of IC3201 as specified?
Check IC3201 and its peripheral
parts.
Are inputs at pins (2) and (4) as well as outputs
at pins (8) and (12), all of IC3304, as specified?
Check the speakers and their peripheral parts.
Check the line in question, IC3304 and
its peripheral parts.