Troubleshooting Table; Power Unit Operation Check - Sharp LC-32A28L Service Manual

CHAPTER 4.

TROUBLESHOOTING TABLE

[1] 32" TROUBLESHOOTING TABLE
↓
Are the power cord and harness in the unit properly connected?
↓ YES
LINE_FILTER_UNIT:
Is F901 normal?
↓YES
POWER_UNIT
Is BD901 (+320V) output? (Set the main power SW to OFF.)
* When power on/off switch is on ‧‧‧ About +400V
↓YES
Is a voltage of +5V applied to pin (11,12) of connector (CN902)?
(Set the main power SW to OFF.)
↓YES
Are +24V output as for the power on/off switch when it is on?
↓YES
Similarly, is +12V output as for the power on/off switch when it is
on?

Power unit operation check.

2008-03-14
NO
Connect the power cord and harness properly, and turn on the
power.
LINE_FILTER_UNIT:
Isn't L901,L902,RV901,C903,C904,C901,C902, etc. out of
order? Moreover,
NO
circumference circuit is checked.
POWER_UNIT:
BD901, RV902, IC951, etc. out of order?
Moreover, whether the short-circuit with the circumference circuit
is checked.
NO Does the PFC circuit operate normally?
(L906, Q901, D902, D903, IC901 and etc. And, the circuit around
the protection circuit etc. is checked.)
NO
Does the switching circuit operate normally?
Check circuit around the primary side (T901, IC931, Q931,
ZD981, ZD930, D980, D981, ZD981, etc.), the secondary side
(D935, L980, etc.), the AC_DET circuit (ZD982, IC932, IC982,
Q992, Q993, etc.), and the protection circuit.
Does the inverter circuit operate normally?
NO
Check circuit around the primary side (T902,Q951,Q952,IC951,
D951,D952, etc.), the secondary side (D955, L971, ZD967,
IC952, IC953, etc.), the STANDBY circuit (Q988, etc.), and the
protection circuit.
Check +12V circuit of D956, L931, etc.
NO
29
LC-32A28L, LC-42A48L
whether the short-circuit with the