Read Sharp LC-20B4E (serv.man8) Service Manual online
20
LC-20B4E
TROUBLE SHOOTING TABLE
(Continued)
No sound (1/2)
Check all the settings microprocessor's adjust process menu.
Is the pin (53) of
IC2001 in the
"L" state?
Is output at pins
(27) and (28) of
IC1901 normal?
Is output at pins
(1) and (7) of
IC1905 normal?
Yes
Yes
No
No
No
No sound
from front
speakers
Yes
Muting effect is
on. Check the
FSMUTE line.
Check IC1901
and its
peripheral parts.
Check IC1905
and its
peripheral parts.
Is the pin (52) of
IC2001 in the
"L" state?
Is output at pins
(24) and (25) of
IC1901 normal?
Is output at pins
(1) and (7) of
IC304 normal?
Yes
Yes
No
No
No
Yes
Muting effect is
on. Check the
HP_MUTE line.
Check IC1901
and its
peripheral parts.
Check IC304
and its
peripheral parts.
No sound
from
headphone
TV sound
failure
Is output at pins
(33) and (34) of
IC1901 normal?
Is output at pins
(1) and (7) of
IC3501 normal?
Check IC1901
and its
peripheral parts.
Check IC3501
and its
peripheral parts.
Yes
No
No
No
No sound
from output
line
Check the tuner
and its
peripheral parts.
Yes
No
Is output at pin
(11) of Tuner
normal?
Is input at pin
(67) of IC1901.
Check IC1901
and its
peripheral
parts.
Check
Headphone Jack
and connection
cable.
No
Is output at pins
(8) and (12) of
IC3301 normal?
Check IC3301
and its
peripheral parts.
Check front
speaker and
connection
cable.
Yes
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