Sharp LC-42RD2E (serv.man4) Service Manual ▷ View online
LC-42RD2E/S/RU
4 – 1
LC42RD2E
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
YES
Check voltage of C7912. Does it equal to 15V?
Check BD7001, D7803, Q7801, Q7612,
Q7602, Q7901, IC7801, IC7604, IC7901.
Q7602, Q7901, IC7801, IC7604, IC7901.
YES
NO
Check IC7901, R7920, R7921.
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 pin3) signal correct?
NO
Check PB (pin8 and pin3), Q7122, Q7121.
YES
Is UR12V (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.
NO
LC-42RD2E/S/RU
4 – 2
No sound from speakers
No sound output in all modes.
Is the audio signal properly sent from pins (28) (L-ch) and (27)
(R-ch) of IC3001?
NO
Check IC3001 or peripheral circuits.
YES
Is the audio signal of pins (3) (L-ch) and (5) (R-ch) of IC303 (OP-
AMP) sent properly?
AMP) sent properly?
NO
Check SC2704 and P1201 or peripheral circuits. Is the S-MUTE
signal “L”?
signal “L”?
YES
Is the audio signal of pin (4) of IC301 (R-ch)/IC302 (L-ch)
(AUDIO-AMP) sent properly?
(AUDIO-AMP) sent properly?
NO
Check HEAD-PHONE (J1301) or peripheral circuits.
YES
Is the audio signal output of pins (2, 1) (L-ch) and (4, 3) (R-ch) of
P301 (AUDIO-CONNECTOR) normal?
P301 (AUDIO-CONNECTOR) normal?
NO
Check P301 (AUDIO-CONNECTOR) and peripheral circuits.
YES
Check Speaker Box (right and left) and wire harness.
No sound (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.
NO
Refer to “No sound output in all modes”.
NO
Is the SIF signal (SIF_IN+) sent to pin (31) of IC3001 (VCT)?
YES
Check whether +5V and +8V are supplied to pins (33) and (18) of
IC3001 respectively. Or, check peripheral circuits.
IC3001 respectively. Or, check peripheral circuits.
NO
Is the audio signal (SIF) sent from pin (1) of CONNECTOR
(SC2742)?
(SC2742)?
YES
Check pin (31) of IC3001 (VCT) and peripheral circuits.
(TUNER)
NO
Is the audio signal (SIF) sent from pin (12) of IC201 (IF-
DEMOD)?
DEMOD)?
YES
Check Q203 (AMP) and peripheral circuits.
(TUNER)
NO
Is the SIF signal sent to pins (23) and (24) of IC201 (IF-
DEMOD)?
DEMOD)?
YES
Check IC201 and peripheral circuits.
(TUNER)
NO
Is the IF signal sent from pin (17) of TUNER (TU201)?
YES
Check FL202 and peripheral circuits.
NO
Check whether 5V (CONT) and 5V are supplied to pins (1) and
(2) of TUNER (TU201) respectively. Check SDA/SCL and AGC
signal.
(2) of TUNER (TU201) respectively. Check SDA/SCL and AGC
signal.
YES
Replace TUNER (TU201).
LC-42RD2E/S/RU
4 – 3
No sound from external input devices (1)
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 IC3001 (VCT)?
Is IN1-L audio signal sent from pin (6) of SCART1 terminal
(J1101) to pin (14) of IC3001 (VCT)?
NO
Check pins (6) and (2) of SCART1 and connection to an external
input device.
input device.
Is IN1-R audio signal sent from pin (2) of SCART1 terminal
(J1101) to pin (13) of IC3001 (VCT)?
(J1101) to pin (13) of IC3001 (VCT)?
YES
Refer to “No sound output in all modes”.
No sound from external input devices (2)
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 IC3001 (VCT)?
Is IN2-L audio signal sent from pin (27) of SCART2 terminal
(J1101) to pin (12) of IC3001 (VCT)?
NO
Check pins (27) and (23) of SCART2 and connection to an exter-
nal input device.
nal input device.
Is IN2-R audio signal sent from pin (23) of SCART2 terminal
(J1101) to pin (11) of IC3001 (VCT)?
(J1101) to pin (11) of IC3001 (VCT)?
YES
Refer to “No sound output in all modes”.
No sound from external input devices (3)
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 IC3001 (VCT)?
Is IN3-L audio signal sent from pin (3) of J1201 terminal to pin
(16) of IC3001 (VCT)?
NO
Check pins (3) and (5) of EXT3 (J1201) and connection to an
external input device.
external input device.
Is IN3-R audio signal sent from pin (5) of J1201 terminal to pin
(15) of IC3001 (VCT)?
(15) of IC3001 (VCT)?
YES
Refer to “No sound output in all modes”.
No sound from external input devices (4)
No sound from EXT4 (AUDIO) connecting an external input
device.
<EXT4>
Is D-SUB-L audio signal sent from J2711 to pin (15) of IC2721
(SW)?
Is D-SUB-L audio signal sent from J2711 to pin (15) of IC2721
(SW)?
NO
Check the line between J2711 and IC2721.
(Q2711, Q2712, etc.)
(Q2711, Q2712, etc.)
Is D-SUB-R audio signal sent from J2711 to pin (2) of IC2721
(SW)?
(SW)?
YES
Is D-SUB-L audio signal sent to pin (10) of IC3001?
Is D-SUB-R audio signal sent to pin (9) of IC3001?
Is D-SUB-R audio signal sent to pin (9) of IC3001?
NO
Check the line between IC2721 and IC3001.
YES
Refer to “No sound output in all modes”.
LC-42RD2E/S/RU
4 – 4
No sound from external input devices (5)
No sound from EXT5 (AUDIO) connecting an external input
device.
Check that Option-HDMI Setup-Audio select is set to “Analog”.
<EXT5>
OK
Is HDMI-L audio signal sent from J2701 terminal to pin (14) of
IC2721 (SW)?
IC2721 (SW)?
NO
Check the line between J2701 and IC2721.
(Q2701, Q2702, etc.)
(Q2701, Q2702, etc.)
Is HDMI-R audio signal sent from J2701 terminal to pin (5) of
IC2721 (SW)?
IC2721 (SW)?
YES
Is HDMI-L audio signal sent to pins (10) of IC3001?
Is HDMI-R audio signal sent to pins (9) of IC3001?
Is HDMI-R audio signal sent to pins (9) of IC3001?
NO
Check output of pins (13) and (3) of IC2721 and peripheral cir-
cuits.
cuits.
YES
Refer to “No sound output in all modes”.
No sound from external input devices (6)
No sound from an external input device connected to EXT7.
<EXT7>
Is EX-L audio signal sent from pin (5) of J1201 terminal to pin
(12) of IC2721 (SW)?
Is EX-L audio signal sent from pin (5) of J1201 terminal to pin
(12) of IC2721 (SW)?
NO
Check the line between J1401 and IC2721.
(Q1401, Q1402, P1401/P2791, etc.)
(Q1401, Q1402, P1401/P2791, etc.)
Is EX-R audio signal sent from pin (4) of J1201 terminal to pin (1)
of IC2721 (SW)?
of IC2721 (SW)?
YES
Is EX-L audio signal sent to pin (10) of IC3001 (VCT)?
Is EX-R audio signal sent to pin (9) of IC3001 (VCT)?
Is EX-R audio signal sent to pin (9) of IC3001 (VCT)?
NO
Check the line between IC2721 and IC3001.
YES
Refer to “No sound output in all modes”.