Sharp LC-20B8US, Service Manual

Page: 32 / 128

32
LC-20B8U-S
LC-20B9U-S
LC-20B9U-SM
TROUBLE SHOOTING TABLE
(Continued)
No sounds come out.
No sounds come out from the speak
ers
.
Ye
s
Ye
s
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"?
Chec
k the per
ipher
al par
ts of IC3201.
Ye
s
Ye
s
Ye
s
No
No No No No
P
e
rf
or
m chec
king from Q3403 to pin
(58) of IC2001.
P
erf
or
m the f
ollo
wing chec
king.
1
No
TV sounds come out:
Chec
k the
per
ipher
al par
ts of Q3203, Q3204 and
the per
ipher
al par
ts of
TU3401.
2
No input 3 sounds come out:
P
erf
or
m
chec
king from J3403 to pins (2) and (4)
of IC3401.
3
No input 4 sounds come out:
P
erf
or
m
chec
king from J3403 to pins (9) and
(11) of IC3401.
4
No input 1 input sounds come out:
P
erf
or
m chec
king from J3405 to pins
(46) and (48) of IC3401.
5
No input 2 sounds come out:
P
erf
or
m
chec
king from J3405 to pins (22) and
(24) of IC3401.
6
No PC input sounds come out:
P
erf
or
m
chec
king from J3409 to pins (47) and
(48) of IC3201.
Chec
k Q3403, Q3401 and Q3402.
Ye
s
No
Chec
k the input line and its
per
ipher
al par
ts
.
Is pin (43) of IC2001 at "L"?
Ye
s
No No
P
e
rf
or
m chec
king from Q3413 to
pin (43) of IC2001.
Ye
s
Chec
k J3403 and its per
ipher
al par
ts
.
Ye
s
Chec
k the per
ipher
al par
ts of IC3404.
Do all the input modes (TV
, Input 1~4) f
a
il to
produce sounds? P
e
rf
or
m the f
o
llo
wing chec
king.
1
Is the monitor output set to "Sound Fix
ed" or
"Sound V
a
ri
ab
le"?
2
Is the sound v
o
lume le
v
e
l sufficient?
3
Is the m
u
ting eff
ect tur
ned off?
4
Are the headphones disconnected?
Do the f
o
llo
wing.
1
Set the monitor output to "Sound
Fix
ed".
2
Raise the sound v
o
lume le
v
e
l.
3
T
u
rn
off the m
u
ting eff
ect.
4
Disconnect the headphones
.
P
e
rf
or
m the f
o
llo
wing chec
king.
1
Do sounds come out from the speak
ers?
2
Is the monitor output connected proper
ly?
3
Is the m
u
ting eff
ect tur
ned off?
Is the audio signal outputted from pins (36) (Rch) and (37) (Lch) of IC3201?
Do the f
o
llo
wing.
1
P
e
rf
or
m chec
king according to the
steps under "No sounds come out from the speak
ers".
2
Connect the monitor output
proper
ly
.
3
T
u
rn
off the m
u
ting eff
ect.
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
Ye
s
No
Ye
s
Ye
s
No
Is pin (53) of IC2001 at
“L
”?
Muting eff
ect is on.
Chec
k 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.