Sharp LC-37XD1E, Service Manual

Page: 33 / 198

LC-37XD1E/RU
4 – 2
No sound (1) (during the reception of TV broadcasting)
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)?
NO
Is the SIF signal
() sent to pin
(67) of IC3701(MSP)? YES Check w5V and
+8V are supplied to pins
(12) and (39) of IC3701
respectively. Or,check
peripheral circuits.
(AV-UNIT) YES NO
Is the audio signal of pins
(3) and (5) of IC303 (OP-
AMP) sent properly? NO Check SC2704
and P1201 or
peripheral circuits.
Is the S-MUTE sig-
nal “L” ? Is the audio signal (SIF)
sent from pin (1) of CON-
NECTOR (SC2705)? YES Check pin (67) of IC3701
(MSP) and peripheral cir-
cuits.
YES (TUNER) NO
Is the audio signal of pin
(4) of IC301/IC302
(AUDIO-AMP) sent prop-
erly? NO Check HEAD-
PHONE
(J1301) or periph-
eral circuits. Is the audio signal (SIF)
sent from Q210 (Buffer)? YES Check CONNEC-
TOR(P201) and periph-
eral circuits.
YES NO
Is the audio signal output
of pins (2) and (4) of P301
(AUDIO-CONNECTOR)
normal ? NO Check P301
(AUDIO- CON-
NECTOR) and
peripheral circuits. Is the SIF signal sent to
Q203 (AMP)? YES Confirm w8V is
supplied to Q203. Or,
please check the periph-
eral circuit.
YES NO
Check SP-BOX (right and
left) and wire harness. Is the SIF signal sent from
pin (13) of TUNER
(TU201)? YES Check soldering the ter-
minal
and peripheral circuits.
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. YES Replace TUNER
(TU201).