Sharp LC-19LS410UT, Service Manual

Page: 30 / 115

LC-19LS410UT, LC-22LS510UT
30
CHAPTER 4.
TROUBLESHOOTING TABLE
[1] TROUBLESHOOTING TABLE(19” and 22”)
Power unit operation check.
↓
LINE_FILTER_UNIT:
↓ YES
POWER_UNIT
↓ 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
Is F901 and F902 normal?
NO
LINE_FILTER_UNIT:
Isn't L902, C908 etc. out of order? Moreover, whether the short-
circuit with the circumference circuit is checked.
POWER_UNIT:
BD901, RV901,RV902,RV903, IC901, 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.)
Does the AC in circuit normally?
(F901,F902,L902,BD901 and etc. And, the circuit around the AC
in circuit etc. is checked.)
NO
Is a voltage of +5V applied to pin (4,5) of connector (CN902)? (Set
the main power SW to OFF.)
Does the switching circuit operate normally?
Check circuit around the primary side (T901, IC901, C907, C937,
Q903 etc.), the secondary side (D905, L904,ZD902 etc.) the
STANDBY circuit (Q988, etc.), and the protection circuit.
NO
Are +16V output as for the power on/off switch when it is on?
NO
Does the converter circuit operate normally?
Check circuit around the primary side (T901, IC901, C907, C937,
Q903 etc.), the secondary side (D902, L903, ZD902 etc.), the
STANDBY circuit (Q988, etc.), and the protection circuit.