Read Sharp LC-37XD1E (serv.man4) Service Manual online
LC-37XD1E/RU
4 – 1
LC-37XD1E
Service Manual
CHAPTER 4.
TROUBLESHOOTING TABLE
[1] TROBLESHOOTING TABLE
Power unit operation check.
Are the power cord and har-
ness in the unit properly con-
nected ?
ness in the unit properly con-
nected ?
NO
Connect the power cord
and harness properly,
and turn on the power.
and harness properly,
and turn on the power.
YES
Is F701 normal ?
NO
Are both ends of C704
and C715 short-cir-
cuited when checking
their resistance values?
and C715 short-cir-
cuited when checking
their resistance values?
NO
Replace F701.
YES
YES
C704
⋅⋅⋅ Check VA701 ,
VA702 and D701.
C715
C715
⋅⋅⋅ Check IC704
and 705.
Is a voltage of BU5V applied
to pin (20) of P701?
(Set the main power SW to
OFF.)
to pin (20) of P701?
(Set the main power SW to
OFF.)
NO
Is a voltage of approx. 8
- 15V to pin (4) of
IC705?
- 15V to pin (4) of
IC705?
NO
Check IC705,
IC708, D725 and
Q724.
IC708, D725 and
Q724.
YES
YES
Check short circuit of 5V
line (D737, C752, etc.).
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 sup-
plied?
clatters twice as soon as the
main power SW is set to ON
and the power is not sup-
plied?
NO
Does a relay noise
sound? (Once)
sound? (Once)
NO
Are PCON1 and 2
[pins (1) and (2)
of P702] at Hi
(3V or more)?
[pins (1) and (2)
of P702] at Hi
(3V or more)?
YES
YES
YES
Check peripheral cir-
cuits of D738, R828 and
D735.
cuits of D738, R828 and
D735.
Check peripheral
circuits of Q712,
Q713, Q721,
Q723 and RY701.
circuits of Q712,
Q713, Q721,
Q723 and RY701.
NO
There is a possibility that control
by P-CON is not performed
properly. Check whether the
"PCON1" and "PCON2" signals
are sent from pins (A23) and
(A21) of IC3002 (V-PRO.) of
MAIN-UNIT.
by P-CON is not performed
properly. Check whether the
"PCON1" and "PCON2" signals
are sent from pins (A23) and
(A21) of IC3002 (V-PRO.) of
MAIN-UNIT.
Does the same symptom
appear even if R858 (2.7k) is
removed and the power is
supplied again ?
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
problems, check the resistance value between pins (1)
and (6) of P704.
When the value is low (several
Ω- several hundred Ω),
disconnect P704. If the value is still low, the parts of 24V
line are defective.
When the resistance value is several k
line are defective.
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.
IC707, D751 , D753, D754,
D741 , D759 and D746.
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.
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)?
sent from pins (28) and
(27) of IC3701 (MSP)?
NO
Is the SIF signal
(ANA_IN1+) sent to pin
(67) of IC3701(MSP)?
(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.
+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?
(3) and (5) of IC303 (OP-
AMP) sent properly?
NO
Check SC2704
and P1201 or
peripheral circuits.
Is the S-MUTE sig-
nal “L” ?
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)?
sent from pin (1) of CON-
NECTOR (SC2705)?
YES
Check pin (67) of IC3701
(MSP) and peripheral cir-
cuits.
(MSP) and peripheral cir-
cuits.
YES
(TUNER)
NO
Is the audio signal of pin
(4) of IC301/IC302
(AUDIO-AMP) sent prop-
erly?
(4) of IC301/IC302
(AUDIO-AMP) sent prop-
erly?
NO
Check HEAD-
PHONE
(J1301) or periph-
eral circuits.
PHONE
(J1301) or periph-
eral circuits.
Is the audio signal (SIF)
sent from Q210 (Buffer)?
sent from Q210 (Buffer)?
YES
Check CONNEC-
TOR(P201) and periph-
eral circuits.
TOR(P201) and periph-
eral circuits.
YES
NO
Is the audio signal output
of pins (2) and (4) of P301
(AUDIO-CONNECTOR)
normal ?
of pins (2) and (4) of P301
(AUDIO-CONNECTOR)
normal ?
NO
Check P301
(AUDIO- CON-
NECTOR) and
peripheral circuits.
(AUDIO- CON-
NECTOR) and
peripheral circuits.
Is the SIF signal sent to
Q203 (AMP)?
Q203 (AMP)?
YES
Confirm whether +8V is
supplied to Q203. Or,
please check the periph-
eral circuit.
supplied to Q203. Or,
please check the periph-
eral circuit.
YES
NO
Check SP-BOX (right and
left) and wire harness.
left) and wire harness.
Is the SIF signal sent from
pin (13) of TUNER
(TU201)?
pin (13) of TUNER
(TU201)?
YES
Check soldering the ter-
minal
and peripheral circuits.
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.
and 5V are supplied to
pins (4) and (10) of
TUNER (TU201) respec-
tively. Check SDA/SCL
and AGC signal.
YES
Replace TUNER
(TU201).
(TU201).
LC-37XD1E/RU
4 – 3
No sound from external input devices (2) -1
No sound from an external input
device connected to EXT1
(SCART1).
device connected to EXT1
(SCART1).
No sound from an external
input device connected to
EXT2 (SCART2).
input device connected to
EXT2 (SCART2).
No sound from an external input
device connected to EXT3.
device connected to EXT3.
<EXT1>
Is IN1-L audio signal sent from
pin (6) of SCART1 terminal
(J1101) to pin (53) of IC3701
(MSP)?
Is IN1-R audio signal sent from
pin (2) of SCART1 terminal
(J1101) to pin (54) of IC3701
(MSP)?
Is IN1-L audio signal sent from
pin (6) of SCART1 terminal
(J1101) to pin (53) of IC3701
(MSP)?
Is IN1-R audio signal sent from
pin (2) of SCART1 terminal
(J1101) to pin (54) of IC3701
(MSP)?
YES
<EXT2>
Is IN2-L audio signal sent
from pin (27) of SCART2 ter-
minal (J1101) to pin (56) of
IC3701 (MSP)?
Is IN2-R audio signal sent
from pin (23) of SCART2 ter-
minal (J1101) to pin (57) of
IC3701 (MSP)?
Is IN2-L audio signal sent
from pin (27) of SCART2 ter-
minal (J1101) to pin (56) of
IC3701 (MSP)?
Is IN2-R audio signal sent
from pin (23) of SCART2 ter-
minal (J1101) to pin (57) of
IC3701 (MSP)?
YES
<EXT3>
Is IN3-L audio signal sent from
pin (3) of
J1201 terminal to pin (47) of
IC3701?
Is IN3-R audio signal sent from
pin (5) of J1201 terminal to pin
(48) of IC3701?
Is IN3-L audio signal sent from
pin (3) of
J1201 terminal to pin (47) of
IC3701?
Is IN3-R audio signal sent from
pin (5) of J1201 terminal to pin
(48) of IC3701?
NO
NO
NO
Check pins (6) and (2) of
SCART1 and connection to an
external input device.
SCART1 and connection to an
external input device.
Check pins (27) and (23) of
SCART2 and connection to
an external input device.
SCART2 and connection to
an external input device.
Check pins 3 and 5 of EXT3
(J1201) and connection to an
external input device.
(J1201) and connection to an
external input device.
Is the audio signal properly sent from pins (28) and (27) of IC3701 ?
NO
YES
Check IC3701 or peripheral circuits.
Is the audio signal of pins (1)
and (7) of IC303 (OP-AMP)
sent properly?
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?
pins (13) and (16) of IC302/
IC301(MAIN-AMP) normal?
NO
Check IC302/IC301 (MAIN-AMP), HEAD-
PHONE and peripheral circuits.
PHONE and peripheral circuits.
YES
.
Check
CONNECTOR(P301)
and SP-BOX(right and left).
LC-37XD1E/RU
4 – 4
No sound from external input devices (2) -2
No sound from EXT4 (AUDIO)
connecting an external input
device.
connecting an external input
device.
No sound from EXT5
(AUDIO) connecting an exter-
nal input device.
(AUDIO) connecting an exter-
nal 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?
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?
<EXT5>
Is HDMI-L audio signal sent
from J2701 to pin (14) of
IC2704?
Is HDMI-R audio signal sent
from J2701 to pin (5) of
IC2704?
Is HDMI-L audio signal sent
from J2701 to pin (14) of
IC2704?
Is HDMI-R audio signal sent
from J2701 to pin (5) of
IC2704?
YES
YES
Is D-SUB-L audio signal sent to
pin (50) of IC3701?
Is D-SUB-R audio signal sent to
pin (51) of IC3701?
pin (50) of IC3701?
Is D-SUB-R audio signal sent to
pin (51) of IC3701?
Is HDMI-L audio signal sent
to pin (50) of IC3701?
Is HDMI-R audio signal sent
to pin (51) of IC3701?
to pin (50) of IC3701?
Is HDMI-R audio signal sent
to pin (51) of IC3701?
NO
Check output of pins (13) and (3) of IC2704
and peripheral circuits.
and peripheral circuits.
YES
YES
Is the audio signal properly sent from pins (28) and (27) of IC3701 ?
NO
Check IC3701 or peripheral circuits.
YES
Is the audio signal of pins (1)
and (7) of IC303 (OP-AMP)
sent properly?
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?
pins (13) and (16) of IC302/
IC301(MAIN-AMP) normal?
NO
Check IC302/IC301 (MAIN-AMP), HEAD-
PHONE and peripheral circuits.
PHONE and peripheral circuits.
YES
.
Check
CONNECTOR(P301)
and SP-BOX(right and left).