Sharp LC-20A2U, Service Manual

Page: 13 / 42

13
LC-20A2U
TROUBLE SHOOTING TABLE
(Continued)
No sound fr
om
speaker
s
Yes
No
Is pin (53) of IC2001 at
“L
”?
Chec
k all the settings on the microprocessor
’s adjust process men
u.
No sound
No
Are outputs at pins (1) and (7) of IC903 as specified?
Yes
No
Are inputs and outputs of IC303 as specified?
Yes
No
Are inputs at pins (11) and (16) as w
e
ll as
outputs at pins (3) and (5), all of IC7305, as specified?
Muting eff
e
ct is
on.
Chec
k the
FSMU line
.
Chec
k IC901,
IC903 and their per
ipher
al
par
ts
.
Chec
k IC303
and its per
ipher
al
par
ts
.
Chec
k the line
in question, IC7305 and its per
ipher
al
par
ts
.
Yes
Chec
k
the
speak
ers and
their per
ipher
al
par
ts
.
No sound fr
om
headphone
Yes
No
Is pin (55) of IC2001 at
“L
”?
Chec
k the
headphone and its per
ipher
al
par
ts
.
Chec
k Q306,
J4001 and their per
ipher
al
par
ts
.
No sound fr
om output
line
Yes
No
Is pin (52) of IC2001 at
“L
”?
No
Are outputs at pins (1) and (7) of IC902 as specified?
Yes
Chec
k the line
in question.
Chec
k the
LMUTE line
.
Chec
k
IC902
and its per
ipher
al
par
ts
.
TV sound failure
Yes
No
Is output at pin (16) of tuner as specified?
No
Is input at pin (60) of IC901 as specified?
Chec
k the
tuner and its per
ipher
al
par
ts
.
Chec
k IC901,
Q3301, Q3204, Q3205 and their per
ipher
al
par
ts
.