Read Sharp LC-42AD5E (serv.man4) Service Manual online
LC-42AD5E/RU/S
4 – 1
LC-42AD5EB
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, BD7001, Z7801, L7801. Are they ok?
NO
Change F7001, BD7001, Z7801, L7801. Turn on again.
Does fuse open again?
Does fuse open again?
YES
YES
Check BD7001, D7803, Q7801, Q7612, Q7602, Q7901,
IC7801, IC7604, IC7901, etc.
IC7801, IC7604, IC7901, etc.
Is there a voltage of 400V in both ends of C7800?
NO
Check IC7801, L7802, L7801, Q7801, Q7803, D7803, etc.
YES
Check voltage of Emitter (Q7902). Does it equal to 15V?
NO
Check IC7901, R7920, R7921, Q7901.
YES
Is BU5V (PA pin20 and pin21) output 5V?
Is UR5V (PA pin10-15) output 5V?
Is UR5V (PA pin10-15) output 5V?
NO
Check IC7901, Q7901, D7951, R7950, R7951, R7961, L7951,
IC7952, etc.
IC7952, etc.
YES
Is P-CON1 (PB pin1) signal normaly?
NO
Check PB (pin1), Q7272, Q7240, Q7241, Q7311, etc.
YES
Is P-CON2 (PB pin2) signal normaly?
NO
Check PB (pin2), Q7309, IC7304, Q7903, etc.
YES
Is UR37V (PA pin1) output 35V?
Is UR13V (PA pin4-6) output 13V?
Is S24V (PC pin1-3) output 24V?
Is UR13V (PA pin4-6) output 13V?
Is S24V (PC pin1-3) output 24V?
NO
Check C7270, C7272, D7271, D7272, Q7271, Q7270, D7274,
D7180, IC7150, L7150, D7240, Q7242, D7275, IC7241,
L7241, etc.
D7180, IC7150, L7150, D7240, Q7242, D7275, IC7241,
L7241, etc.
YES
Is INV24V (LD pin1-5/LA pin1-5) output 24V?
NO
Check IC7604, Q7612, Q7602, T7301, T7001, D7200, D7201,
R7201-3, L7200, etc.
R7201-3, L7200, etc.
LC-42AD5E/RU/S
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 IC3002?
NO
Check IC3002 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 IC3002 (VCT)?
YES
Check whether +5V and +8V are supplied to pins (33) and (18) of
IC3002 respectively. Or, check peripheral circuits.
IC3002 respectively. Or, check peripheral circuits.
NO
Is the audio signal (SIF) sent from pin (1) of CONNECTOR
(SC2705)?
(SC2705)?
YES
Check pin (31) of IC3002 (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-42AD5E/RU/S
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 IC3002 (VCT)?
Is IN1-L audio signal sent from pin (6) of SCART1 terminal
(J1101) to pin (14) of IC3002 (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 IC3002 (VCT)?
(J1101) to pin (13) of IC3002 (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 IC3002 (VCT)?
Is IN2-L audio signal sent from pin (27) of SCART2 terminal
(J1101) to pin (12) of IC3002 (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 IC3002 (VCT)?
(J1101) to pin (11) of IC3002 (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 IC3002 (VCT)?
Is IN3-L audio signal sent from pin (3) of J1201 terminal to pin
(16) of IC3002 (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 IC3002 (VCT)?
(15) of IC3002 (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 J2702 to pin (15) of IC2704
(SW)?
Is D-SUB-L audio signal sent from J2702 to pin (15) of IC2704
(SW)?
NO
Check the line between J2702 and IC2704.
(Q2703, Q2706, etc.)
(Q2703, Q2706, etc.)
Is D-SUB-R audio signal sent from J2702 to pin (2) of IC2704
(SW)?
(SW)?
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?
Is D-SUB-R audio signal sent to pin (9) of IC3002?
NO
Check the line between IC2704 and IC3002.
YES
Refer to “No sound output in all modes”.
LC-42AD5E/RU/S
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
IC2704 (SW)?
IC2704 (SW)?
NO
Check the line between J2701 and IC2704.
(Q2704, Q2705, etc.)
(Q2704, Q2705, etc.)
Is HDMI-R audio signal sent from J2701 terminal to pin (5) of
IC2704 (SW)?
IC2704 (SW)?
YES
Is HDMI-L audio signal sent to pins (10) of IC3002?
Is HDMI-R audio signal sent to pins (9) of IC3002?
Is HDMI-R audio signal sent to pins (9) of IC3002?
NO
Check the line between IC2704 and IC3002.
YES
Refer to “No sound output in all modes”.
