LC-42XD1E (serv.man5). Troubleshooting Table - Sharp TV Service Manual (repair manual). Page 2

LC-42XD1E/RU

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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 
(ANA_IN1+) sent to pin 
(67) of IC3701 (MSP)?

YES

Check whether +5V 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 signal “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 peripheral cir-
cuits. 

Is the audio signal (SIF) 
sent from Q210 (Buffer)? 

YES

Check CONNECTOR 
(P201) and peripheral cir-
cuits.

YES

NO

Is the audio signal output 
of pins (2) and (4) of P301 
(AUDIO-CONNECTOR) 
normal? 

NO

Check P301 (AUDIO- 
CONNECTOR) and 
peripheral circuits. 

Is the SIF signal sent to 
Q203 (AMP)?

YES

Confirm whether +8V is 
supplied to Q203.
Or, please check the 
peripheral 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 termi-
nal 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).