LC-37XD1E (serv.man4). Troubleshooting Table - Sharp TV Service Manual (repair manual). Page 2

     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 
(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 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 whether +8V 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).