Read Sharp LC-20M4E (serv.man3) Service Manual online
LC-20M4E
16
No sound
Check all the settings microprocessor's adjust process menu.
Is pin (53) of
IC2001 at "L"
state?
Are outputs at
pins (1) and (7)
of IC903 as
specified?
Are inputs and
outputs of IC303
as specified?
Yes
Yes
No
No
No
No
No sound
from front
speakers
No sound
from rear
speakers
Are inputs at
pins (5) and (8)
as well as
outputs at pins
(2) and (11),
all of IC301, as
specified?
Yes
Muting effect is
on. Check the
FSMU line.
Check IC901,
IC903 and their
peripheral parts.
Check IC303
and its
peripheral parts.
Check the line
in question.
IC303 and its
peripheral parts.
Check RY351,
speakers and
their peripheral
parts.
Yes
Is pin (54) of
IC2001 at "L"
state?
Are input at pin
(5) as well as
output at pin
(2) of IC302 as
specified?
Check the
speaker and its
peripheral parts.
Yes
Yes
No
No
Muting effect is
on. Check the
FSMU line.
Check the line
IC901, IC303
and their
peripheral parts.
No sound
from
headphone
Is pin (55) of
IC2001 at "L"
state?
Check the
headphone and
its peripheral
parts.
Check Q371,
J4001 and their
peripheral parts.
Yes
No
No
No sound
from output
line
Is pin (52) of
IC2001 at "L"
state?
Are output at
pin (1) and (7)
of IC902 as
specified?
Check the
LMUTE line.
Check IC902,
and its
peripheral parts.
Yes
No
Check the line
in question.
Yes
TROUBLE SHOOTING TABLE
(Continued)
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