Sharp LC-32A28L, Service Manual

Page: 36 / 118

LC-32A28L, LC-42A48L
36
42” TROUBLESHOOTING TABLE
Power unit operation check.
↓
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 and F902 normal?
NO
LINE_FILTER_UNIT:
Isn't L901,L902,RV902,RV904,C908,C909,, etc. out of order?
Moreover, whether the short-circuit with the circumference circuit
is checked.
POWER_UNIT:
BD901,Q901,Q920,Q919,IC903, 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, Q902, D903, 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, ZD910,
ZD911, ZD913, D908, D924, D939, ZD912, Q924 ,IC911 etc.),
the secondary side (D927, L907, IC913, Q918 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,Q919,Q920,IC901,
D931,D932,Q922,D933,Q917,Q923 etc.), the secondary side
(D901,D902,L906 , IC914, IC910, 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.