Sharp LC-26SB25E Service Manual ▷ View online
2008-03-14
LC-26SB25E/S/RU, LC-32SB25E/S/RU, LC-42SB55E/S/RU
37
CHAPTER 4.
TROUBLESHOOTING TABLE
[1] TROUBLESHOOTING TABLE
Power unit operation check(for LC-42SB55).
↓
LINE_FILTER_UNIT:
↓ YES
POWER_UNIT
↓YES
↓YES
↓YES
↓YES
Are the power cord and harness in the unit properly connected?
NO
Connect the power cord and harness properly, and turn on the
power.
power.
Is F901 normal?
NO
LINE_FILTER_UNIT:
Isn't L901,L902,RV902,C908,C909,C901,C902, etc. out of
order? Moreover, whether the short-circuit with the
circumference circuit is checked.
POWER_UNIT:
BD901, RV904, IC902, TH901, etc. out of order?
Moreover, whether the short-circuit with the circumference circuit
is checked.
Isn't L901,L902,RV902,C908,C909,C901,C902, etc. out of
order? Moreover, whether the short-circuit with the
circumference circuit is checked.
POWER_UNIT:
BD901, RV904, IC902, TH901, etc. out of order?
Moreover, whether the short-circuit with the circumference circuit
is checked.
Is BD901 (+320V) output? (Set the main power SW to OFF.)
* When power on/off switch is on ‧‧‧ About +400V
* When power on/off switch is on ‧‧‧ About +400V
Does the PFC circuit operate normally?
(L903, L964, Q925, ZD914, D930, Q902, IC902 and etc. And,
the circuit around the protection circuit etc. is checked.)
(L903, L964, Q925, ZD914, D930, Q902, IC902 and etc. And,
the circuit around the protection circuit etc. is checked.)
NO
Is a voltage of +5V applied to pin (11,12) of connector (CN902)?
(Set the main power SW to OFF.)
(Set the main power SW to OFF.)
Does the switching circuit operate normally?
Check circuit around the primary side (T904, IC903, Q922,
Q924, ZD911, D924, D908, ZD910, etc.), the secondary side
(D927, L907, etc.), the AC_DET circuit (ZD912, ZD913, IC911,
IC913, Q918, IC909, Q915, etc.), and the protection circuit.
Check circuit around the primary side (T904, IC903, Q922,
Q924, ZD911, D924, D908, ZD910, etc.), the secondary side
(D927, L907, etc.), the AC_DET circuit (ZD912, ZD913, IC911,
IC913, Q918, IC909, Q915, etc.), and the protection circuit.
NO
Are +24V output as for the power on/off switch when it is on?
NO
Does the inverter circuit operate normally?
Check circuit around the primary side (T905,Q920,Q919,IC901,
Q917,Q923,D936,D937,D932,ZD915,ZD916, etc.), the
secondary side (D901, D902, L906, L908, IC910, IC914, etc.),
the STANDBY circuit (Q915, etc.), and the protection circuit.
Check circuit around the primary side (T905,Q920,Q919,IC901,
Q917,Q923,D936,D937,D932,ZD915,ZD916, etc.), the
secondary side (D901, D902, L906, L908, IC910, IC914, etc.),
the STANDBY circuit (Q915, etc.), and the protection circuit.
Similarly, is +12V output as for the power on/off switch when it is
on?
on?
NO
Check +12V circuit of D928, L909, etc.
LC-26SB25E/S/RU, LC-32SB25E/S/RU, LC-42SB55E/S/RU
38
Power unit operation check(for LC-32SB25 and LC-26SB25).
↓
LINE_FILTER_UNIT:
↓ YES
POWER_UNIT
↓YES
↓YES
↓YES
↓YES
Are the power cord and harness in the unit properly connected?
NO
Connect the power cord and harness properly, and turn on the
power.
power.
Is F901 normal?
NO
LINE_FILTER_UNIT:
Isn't L901,L902,RV90
Isn't L901,L902,RV90
1
,C90
3
,C90
4
,C901,C902, etc. out of
order? Moreover, whether the short-circuit
with the
circumference circuit is checked.
POWER_UNIT:
BD901, RV90
POWER_UNIT:
BD901, RV90
2
, IC9
51
, etc. out of order?
Moreover, whether the short-circuit with the circumference circuit
is checked.
is checked.
Is BD901 (+320V) output? (Set the main power SW to OFF.)
* When power on/off switch is on ‧‧‧ About +400V
* When power on/off switch is on ‧‧‧ About +400V
Does the PFC circuit operate normally?
(L90
(L90
6
, Q9
01
,
D902
,
D903
, IC90
1
and etc. And, the circuit around
the protection circuit etc. is checked.)
NO
Is a voltage of +5V applied to pin (11,12) of connector (CN902)?
(Set the main power SW to OFF.)
(Set the main power SW to OFF.)
Does the switching circuit operate normally?
Check circuit around the primary side (T90
Check circuit around the primary side (T90
1
, IC9
31
, Q9
31
,
ZD981
, ZD9
30
, D9
80
, D98
1
, ZD9
81
, etc.), the secondary side
(D9
35
, L9
80
, etc.), the AC_DET circuit (ZD9
8
2, IC9
32
, IC9
82
,
Q9
92
, Q9
93
, etc.), and the protection circuit.
NO
Are +24V output as for the power on/off switch when it is on?
NO
Does the inverter circuit operate normally?
Check circuit around the primary side (T90
Check circuit around the primary side (T90
2
,Q9
51
,Q9
52
,IC9
5
1,
D9
51
,D9
52
, etc.), the secondary side (D9
55
, L9
71
, ZD
967
,
IC9
52
, IC9
53
, etc.), the STANDBY circuit (Q9
88
, etc.), and the
protection circuit.
Similarly, is +12V output as for the power on/off switch when it is
on?
on?
NO
Check +12V circuit of D9
56
, L9
31
, etc.
2008-03-14
LC-26SB25E/S/RU, LC-32SB25E/S/RU, LC-42SB55E/S/RU
39
The sound is not emitted from the speaker though the picture has come out.
↓
No sound output in all modes?
TEREMINAL UNIT:
↓
↓YES
↓YES
↓YES
↓YES
No sound (during the reception of TV(ANALOG) broadcasting)
↓
Does not the sound go out though the picture has come out when UHF/VHF is received?
TEREMINAL UNIT:
↓
↓YES
↓YES
No sound (during the reception of TV (DIGITAL) broadcasting)
↓
Does not the sound go out though the picture has come out when DTV is received?
MAIN UNIT:
↓
↓YES
↓YES
↓YES
Is the audio signal output of pin (F26) (AL1) and pin (G25) (AR1) of
IC U400 normal?
IC U400 normal?
NO
Check IC U400 and its peripheral circuits.
Is audio signal input to pin (2)(L), pin (14)(R) of IC U600 (AMP)?
NO
Check the line between IC U400 and IC U600.
Is MUTE circuit [AMP_MUTE_LINE, POWERUP_LINE] normal?
Is the audio signal output of pin (2, 1) (L-ch) and pin (1, 2) (R-ch) of
CN600 & CN601(AOUDIO-CONNECTOR) normal?
CN600 & CN601(AOUDIO-CONNECTOR) normal?
NO
Check the AMP_MUTE_LINE and POWERUP_LINE. (Q600,
etc.)
etc.)
NO
Check IC U600 and its peripheral circuits.
Check Speaker Box (right and left) and wire harness.
Is the SIF signal output from pin (11) of TUNER (TU200)?
Is the SIF signal sent to pin (P25) and pin (P26) of IC U400?
NO
Check the tuner and its peripheral circuits. Replace as required.
NO
Check IC U400 its peripheral circuits.
Refer to “No sound output in all modes”.
Is the DIF signal output from pin (17) and pin (19) of TUNER
(TU200)?
(TU200)?
NO
Check the tuner and its peripheral circuits. Replace as required.
Refer to “No sound output in all modes”.
Is the DIF signal sent to pin (44) and pin (43) of IC U231?
NO
Check IC U231 its peripheral circuits.
LC-26SB25E/S/RU, LC-32SB25E/S/RU, LC-42SB55E/S/RU
40
No sound from external input devices (1)
↓
Does not the sound of the audio signal input to SCART1 go out?
Does not the sound of the audio signal input to SCART2 go out?
TEREMINAL UNIT:
↓
↓YES
↓YES
No sound from external input devices (2)
↓
Does not the sound of the audio signal input to AV1(Component) go out?
MAIN UNIT:
↓
↓YES
↓YES
No sound from external input devices (3)
↓
Does not the sound of the audio signal input to AV3(Composite/Y/C) go out?
MAIN UNIT:
↓
↓YES
↓YES
Is the audio signal properly sent to pin (6) (SCT1_AUL_IN) and pin
(2) (SCT1_AUR_IN) of SCART1(CN500)?
(2) (SCT1_AUR_IN) of SCART1(CN500)?
Is the audio signal properly sent to pin (6) (SCT2_AUL_IN) and pin
(2) (SCT2_AUR_IN) of SCART2(CN501)?
(2) (SCT2_AUR_IN) of SCART2(CN501)?
Check the setting of an external input device that connects of
CN500.
CN500.
NO
Check the setting of an external input device that connects of
CN501.
CN501.
NO
Is the audio signal properly sent to pin (J25) (SC1_LIN) and pin
(J26) (SC1_RIN) of IC U400?
(J26) (SC1_RIN) of IC U400?
Is the audio signal properly sent to pin (J23) (SC2_LIN) and pin
(J24) (SC2_RIN) of IC U400?
(J24) (SC2_RIN) of IC U400?
NO
NO
Check the line between CN500 and IC U400.
Check the line between CN501 and IC U400.
Refer to “No sound output in all modes”.
Is the audio signal properly sent to pin (2) (AV1_AudioLIN) and pin
(4)(AV1_AudioRIN) of CN553?
(4)(AV1_AudioRIN) of CN553?
NO
Check the connection to CN553 and the external input device.
Refer to “No sound output in all modes”.
Is the audio signal properly sent to pin (K23) (AV1_LIN) and pin
(K24) (AV1_RIN) of IC U400?
(K24) (AV1_RIN) of IC U400?
NO
Check the line between CN553 and IC U400.
Is the audio signal properly sent to pin (4) (AV3_AudioLIN) and pin
(6) (AV3_AudioRIN) of CN650?
(6) (AV3_AudioRIN) of CN650?
NO
Check the connection to CN650 and the external input device.
Refer to “No sound output in all modes”.
Is the audio signal properly sent to pin (L23) (SIDE_LIN) and pin
(L24) (SIDE_RIN) of IC U400?
(L24) (SIDE_RIN) of IC U400?
NO
Check the line between CN650 and IC U400.
Click on the first or last page to see other LC-26SB25E service manuals if exist.