DOWNLOAD Sharp LC-37SA1E (serv.man4) Service Manual ↓ Size: 1.01 MB | Pages: 23 in PDF or view online for FREE

LC-37SA1E/RU/LC-37SV1E/RU

4 – 1

LC-37SA1E

Service Manual

 

                                            
Are the power cord and harness in the unit properly connected ? 

No

Connect the power cord and harness properly, and turn on the 
power.

Yes

Is F701 normal ?

No

Are both ends of C704,C705(37) and C706(37) short-circuited 
when checking their resistance values?

Yes

No

Yes

Replace F701.

Is a voltage of BU5V applied to pin (20) of  P701? 
(Set the main power SW to OFF.) 

C704 

• • • Check VA701 , VA702 and D701. 

C705(37)/C706(37) 

• • • Check IC704 and 705.

Yes

                          

No

Is a voltage of approx. 8 - 15V to pin (4) of IC705?

No

Check IC705, IC708, D725 and Q724.

                          

Yes

Check short circuit of 5V line (D737, C752, etc.).

Is it a symptom that the relay clatters twice as soon as the       
main power SW is set to ON and the power is not supplied?

Yes

                          

Yes

Does the same symptom appear even if R858 (2.7k) 
is removed and the power is supplied again ?

No

Check IC704, D728, D762 and D736. If there are no problems, 
check the resistance value between pins (1) and (6) of P704.
When the value is low (several 

Ω- several hundred Ω),  discon-

nect P704. If the value is still low, the parts of 24V line are defec-
tive. When the resistance value is several k

Ω, check the inverter 

unit. 

                          

Yes

Check Q724, D731 , D734, IC707, D751 , D753, 
D754, D741 ,  D759 and D746.

oes a relay noise sound? (Once) 

No

Are PCON1 and 2 [pins (1) and (2) of  P702] at Hi (3V or more)?

Yes

No

Yes

heck peripheral circuits of D738, R828 and D735. 

Check peripheral circuits of Q712, Q713, 
Q721, Q723 and RY701.

There is a possibility that control by P-CON is not performed
properly. Check whether the "PS-ON" and "PS-ON2" signals 
are sent from pins (97) and (91) of  IC1710 (FPGA) of  MAIN-
UNIT.

LC-37SA1E/RU/LC-37SV1E/RU

4 – 2

                
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 IC3002 (VCT)?

NO

Is the SIF signal (SIF_IN+) 
sent to pin (31) of IC3002 
(VCT)?

YES

Check whether +5V and 
+8V are supplied to pins 
(33) and (18) of IC3002 
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 cicuits. 
Is the S-MUTE signal “L”?

Is the audio signal (SIF) 
sent from pin (1) of 
CONNECTOR (SC2705)?

YES

Check pin (31) of IC3002 
(VCT) and peripheral 
circuits.

YES

(TUNER) NO

Is the audio signal of pin 
(4) Of IC301/IC302 
(AUDIO-AMP) sent 
properly? 

NO

Check HEAD-PHONE 
(J1301) or peripheral 
circuits. 

Is the audio signal (SIF) 
sent from pin (12) of IC201 
(IF-DEMOD)?

YES

Check Connector (P201/
SC2705) and peripheral 
circuits.

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 
pins (23) and (24) of IC201 
(IF-DEMOD)?

YES

Check IC201 and 
peripheral circuits.

YES

NO

Check Speaker (right and 
left) and wire harness.

Is the IF signal sent from 
pin (11) of TUNER 
(TU201)?

YES

Check FL202 and 
peripheral circuits.

NO

 

Check whether 33V and 
5V are supplied to pins (9) 
and (7) of TUNER (TU201) 
respectively. Check SDA/
SCL and AGC signal.

YES

Replace TUNER (TU201).

LC-37SA1E/RU/LC-37SV1E/RU

4 – 3

                                             
No sound from an external input device connected to EXT1 
(SCART1).

                                             
<EXT1>
Is IN1-L audio signal sent from pin (6) of SCART1 terminal 
(J1101) to pin (14) of IC3002 (VCT)?
Is IN1-R audio signal sent from pin (2) of SCART1 terminal 
(J1101) to pin (13) of IC3002 (VCT)?

NO

Check pins (6) and (2) of SCART1 and connection to an external 
input device.

YES

Is the audio signal properly sent from pins (28) and (27) of 
IC3002?

NO

Check IC3002 or peripheral circuits.

YES

Is the audio signal of pins (1) and (7) of IC303 (OP-AMP) sent 
properly?

NO

Check IC303 or peripheral circuits.

YES

Is the audio output signal of pins (13) and (16) of IC302/IC301 
(MAIN-AMP) normal?

NO

Check IC302/IC301 (MAIN-AMP), HEADPHONE and peripheral 
circuits.

YES

Check CONNECTOR (P301) and Speaker (right and left).

                                             
No sound from an external   input device connected to EXT2 
(SCART2). 

                                             
<EXT2>
Is IN2-L audio signal sent from pin (27) of SCART2 terminal 
(J1101) to pin (12) of IC3002 (VCT)?
Is IN2-R audio signal sent from pin (23) of SCART2 terminal 
(J1101) to pin (11) of IC3002 (VCT)?

NO

Check pins (27) and (23) of SCART2 and connection to an 
external input device.

YES

Is the audio signal properly sent from pins (28) and (27) of 
IC3002?

NO

Check IC3002 or peripheral circuits.

YES

Is the audio signal of pins (1) and (7) of IC303 (OP-AMP) sent 
properly?

NO

Check IC303 or peripheral circuits.

YES

Is the audio output signal of pins (13) and (16) of IC302/IC301 
(MAIN-AMP) normal?

NO

Check IC302/IC301 (MAIN-AMP), HEADPHONE and peripheral 
circuits.

YES

Check CONNECTOR (P301) and Speaker (right and left).

LC-37SA1E/RU/LC-37SV1E/RU

4 – 4

                                             
No sound from an external input device connected to EXT3.

                                             
<EXT3>
Is IN3-L audio signal sent from pin (3) of J1201 terminal to pin 
(16) of IC3002? 
Is IN3-R audio signal sent from pin (5) of J1201 terminal to pin 
(15) of IC3002? 

NO

Check pins (3) and (5) of EXT3 (J1201) and connection to an 
external input device. 

YES

Is the audio signal properly sent from pins (28) and (27) of 
IC3002?

NO

Check IC3002 or peripheral circuits.

YES

Is the audio signal of pins (1) and (7) of IC303 (OP-AMP) sent 
properly?

NO

Check IC303 or peripheral circuits.

YES

Is the audio output signal of pins (13) and (16) of IC302/IC301 
(MAIN-AMP) normal?

NO

Check IC302/IC301 (MAIN-AMP), HEADPHONE and peripheral 
circuits.

YES

Check CONNECTOR (P301) and Speaker (right and left).

                                             
No sound from EXT4 (AUDIO) connecting an external input 
device.

                                             
<EXT4>
Is D-SUB-L audio signal sent from J2702 to pin (15) of IC2704? 
Is D-SUB-R audio signal sent from J2702 to pin (2) of IC2704?

YES

Is D-SUB-L audio signal sent to pin (10) of IC3002? 
Is D-SUB-R audio signal sent to pin (9) of IC3002?

YES

Is the audio signal properly sent from pins (28) and (27) of 
IC3002?

NO

Check IC3002 or peripheral circuits.

YES

Is the audio signal of pins (1) and (7) of IC303 (OP-AMP) sent 
properly?

NO

Check IC303 or peripheral circuits.

YES

Is the audio output signal of pins (13) and (16) of IC302/IC301 
(MAIN-AMP) normal?

NO

Check IC302/IC301 (MAIN-AMP), HEADPHONE and peripheral 
circuits.

YES

Check CONNECTOR (P301) and Speaker (right and left).