Sharp LC-26SB25E, Service Manual

Page: 37 / 172

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.
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.
Is BD901 (+320V) output? (Set the main power SW to OFF.)
* 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.)
NO
Is a voltage of +5V applied to pin (11,12) of connector (CN902)?
(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. 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.
Similarly, is +12V output as for the power on/off switch when it is
on?
NO
Check +12V circuit of D928, L909, etc.