Sharp LC-42XD1E (serv.man5) Service Manual ▷ View online
LC-42XD1E/RU
4 – 1
LC-42XD1E
Service Manual
CHAPTER 4.
TROUBLESHOOTING TABLE
[1] TROBLESHOOTING TABLE
Turn on AC source.
Check AC input and output connector. Are they ok?
No
Insert connectors correctly or change them.
Turn on again.
Turn on again.
Yes
Check F7001, R7805, R7901. Are they ok?
No
Change F7001, R7805, R7901. Turn on again.
Does fuse open again?
Does fuse open again?
Yes
No
Yes
Check voltage of C7912. Does it equal 15V?
Yes
No
Check IC7901, R7920, R7921.
Check BD7001, D7803, Q7801, Q7612, Q7602,
Q7901, IC7801, IC7604, IC7901.
Q7901, IC7801, IC7604, IC7901.
Is BU5V (PA pin21+ and pin22-) output 5V?
Is UR5V (PA pin15+ and pin16-) output 5V?
Is UR37V (PA pin1+ and pin2-) output 35V?
Is UR5V (PA pin15+ and pin16-) output 5V?
Is UR37V (PA pin1+ and pin2-) output 35V?
No
Check IC7901, Q7901, D7951, L7951, C7270, C7272, D7271,
D7272, Q7270.
D7272, Q7270.
Yes
Is P-con1 (PB pin1 and pin3) signal correct?
No
Check PB (pin1 and pin3), Q7240, Q7241.
Yes
Is UR13V (PA pin6+ and pin7-) output 13V?
Is S24V (PC pin3+ and pin5-) output 25.5V?
Is S24V (PC pin3+ and pin5-) output 25.5V?
No
Check D7180, IC7150, D7150, L7150, D7240, IC7241, L7241.
Yes
Is LCD-POW (PB pin8 and pin13) signal correct?
NO
Check PB (pin8 and pin3), Q7112,Q7121.
YES
Is UR 12V (PL pin2+ and pin3–) output 12V?
NO
Check Q7104.
Yes
Is P-con2 (PB pin2 and pin3) signal correct?
No
Check PB (pin2 and pin3), Q7309, IC7304.
Yes
Is voltage of C7800 400V?
No
Check IC7801, L7802, Q7801, D7803.
Yes
Is INV24V (LD pin5+ and pin6-) output 24V?
No
Check R7805, IC7604, Q7602, Q7612, D7200, D7201, L7200.
LC-42XD1E/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)?
(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 signal “L”?
or peripheral circuits.
Is the S-MUTE signal “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 peripheral cir-
cuits.
(J1301) or peripheral cir-
cuits.
Is the audio signal (SIF)
sent from Q210 (Buffer)?
sent from Q210 (Buffer)?
YES
Check CONNECTOR
(P201) and peripheral cir-
cuits.
(P201) and peripheral cir-
cuits.
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-
CONNECTOR) and
peripheral circuits.
CONNECTOR) 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
peripheral circuit.
supplied to Q203.
Or, please check the
peripheral 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 termi-
nal and peripheral circuits.
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.
and 5V are supplied to
pins (4) and (10) of
TUNER (TU201) respec-
tively. Check SDA/SCL
and AGC signal.
YES
Replace TUNER (TU201).
LC-42XD1E/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.
input 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 (J1201) and 5
(J1201) of EXT3 and connec-
tion to an external input device.
(J1201) of EXT3 and connec-
tion 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),
HEADPHONE and peripheral circuits.
HEADPHONE and peripheral circuits.
YES
Check CONNECTOR(P301),
SP-BOX (right and left).
SP-BOX (right and left).
LC-42XD1E/RU
4 – 4
No sound from external input devices (2) -2
No sound from EXT4 (AUDIO) connect-
ing an external input device.
ing an external input device.
No sound from EXT5 (AUDIO) connect-
ing an external input device.
ing 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?
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?
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?
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.
IC2704 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?
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) nor-
mal?
(16) of IC302/IC301 (MAIN-AMP) nor-
mal?
NO
Check IC302/IC301 (MAIN-AMP),
HEADPHONE and peripheral circuits.
HEADPHONE and peripheral circuits.
YES
Check CONNECTOR (P301),
SP_substrate (D790WJ/D791WJ) and
SP-BOX (right and left).
SP_substrate (D790WJ/D791WJ) and
SP-BOX (right and left).