Sharp Aquos LC-42D72U, Service Manual

Page: 47 / 162

LC-42D72U
4 – 16
No audio (4)
No audio at digital broadcast
signal reception
No audio at UHF/VHF broad-
cast signal reception
Move the sound volume key.
Does the volume icon indicate
the speakers?
YES
Set the audio output to
“FIXED”. Is the audio output selected for
“VARIABLE” on the menu
screen?
YES
Set the audio output to
“FIXED”.
NO NO
Are there the IF_OUT_N and
IF_OUT_P signal outputs at
pins (20) and (21) of tuner
(TU1101)?
NO
Check the tuner (TU1101)
and its peripheral circuits.
Replace as required. Is there the SIF signal output
at pin (3) of tuner (TU1101)?
NO
Check the tuner
(TU1101) and its
peripheral circuits.
Replace as required.
YES YES
Are there the IF_OUT_N and
IF_OUT_P signal inputs at
pins (10) and (11) of IC8601
(DEMODULATOR)?
NO
Check the line between
tuner (TU1101) and
IC8601, and their periph-
eral circuits (filter circuit,
etc.). Is there the SIF signal input at
pins (21) of IC1401
(SIF_DECODER)?
NO
Check the line
between tuner
(TU1101) and IC1401,
and their peripheral
circuits (Q1102,
Q1103, etc.).
YES YES
Do the US_TS_CLK/DATA/
EN/PKTSYNC signals come
from pins (51, 59, 63 and 66)
of IC8601 to pins (D11, A9,
C10, B10) of IC8101 (CPU/
DECODER)?
NO
Check the line between
IC8601 and IC8101, and
their peripheral circuits. Are the audio signal outputs at
pins (30)(L) and (29)(R) of
IC1401?
NO
Check IC1401
(SIF_DECODER) and
its peripheral circuits.
Replace as required.
YES
Are the audio signal inputs at
pins (51)(L) and (52)(R) of
IC1403?
NO
Check the line
between IC1401 and
IC1403, and their
peripheral circuits.
YES
Is the communication
between IC8101 and IC8801
(DAC) as specified?
(DTV_I2SMCLK/
DTV_I2SCLK/
DTV_I2SLRCK)?
NO
Check the line between
IC8101 and IC8801, and
their peripheral circuits.
YES
YES
Are the DTV_L/R audio signal
outputs at pins (19)(L) and
(18)(R) of IC8801 (DAC)?
NO
Check IC8801 and its
peripheral circuits.
YES