Sharp LC-26SB25E, Service Manual

Page: 38 / 172

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.
Is F901 normal?
NO
LINE_FILTER_UNIT:
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 2 , IC9 51 , 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?
(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.) Does the switching circuit operate normally?
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 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?
NO
Check +12V circuit of D9 56 , L9 31 , etc.