Sharp LC-37XD1E Service Manual page 33

No audio output during UHF/VHF reception
Checklist:
1) Is the volume set to MIN or MUTE on the remote control ? ... Set the desired volume.
2) Are headphones connected to HEADPHONE (J1301 ) ? ... Disconnect them.
3) Is ANT-CABLE disconnected or connected improperly ? ... Connect it correctly as per the operation manual.
Is the audio signal (L/R)
sent from pins (28) and
(27) of IC3701 (MSP)?
(AV-UNIT) YES
Is the audio signal of pins
(3) and (5) of IC303 (OP-
AMP) sent properly?
YES
Is the audio signal of pin
(4) of IC301/IC302
(AUDIO-AMP) sent prop-
erly?
YES
Is the audio signal output
of pins (2) and (4) of P301
(AUDIO-CONNECTOR)
normal ?
YES
Check SP-BOX (right and
left) and wire harness.
No sound (1) (during the reception of TV broadcasting)
NO
NO Check SC2704
and P1201 or
peripheral circuits.
Is the S-MUTE sig-
nal "L" ?
NO Check HEAD-
PHONE
(J1301) or periph-
eral circuits.
NO Check P301
(AUDIO- CON-
NECTOR) and
peripheral circuits.
Is the SIF signal
(ANA_IN1+) sent to pin
(67) of IC3701(MSP)?
NO
Is the audio signal (SIF)
sent from pin (1) of CON-
NECTOR (SC2705)?
(TUNER) NO
Is the audio signal (SIF)
sent from Q210 (Buffer)?
NO
Is the SIF signal sent to
Q203 (AMP)?
NO
Is the SIF signal sent from
pin (13) of TUNER
(TU201)?
NO
Check whether 5V (ANT )
and 5V are supplied to
pins (4) and (10) of
TUNER (TU201) respec-
tively. Check SDA/SCL
and AGC signal.
4 – 2
LC-37XD1E/RU
YES Check whether +5V and
+8V are supplied to pins
(12) and (39) of IC3701
respectively. Or,check
peripheral circuits.
YES Check pin (67) of IC3701
(MSP) and peripheral cir-
cuits.
YES Check CONNEC-
TOR(P201) and periph-
eral circuits.
YES Confirm whether +8V is
supplied to Q203. Or,
please check the periph-
eral circuit.
YES Check soldering the ter-
minal
and peripheral circuits.
YES Replace TUNER
(TU201).