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No power supply (Front LED does not light up) and no power-up even is turned on (Front LED light up to blue)
Is the AC cord connected?
Yes
Are the harness and FFC connected
properly?
Yes
Are F701 normal?
Yes
Is the voltage of C748/C773/C775
approx. 160V?
Yes
Is BU5V supplide?
Yes
Are UR12V supplied?
Yes
Is 24V supplied?
Yes
Turn on the power again,and check if
the unit works normally.
Remarks
(CN802
10
)
State of the set
(CN802
MODE1
-
STDBY
-
MODE2
-
Power ON
TROUBLESHOOTING TABLE
No
Connect the AC cord and turn on the power.
No
Connect the hamess and FFC properly.
No
If the fuse is blown when turning on the power after replacing F701.replace
IC703 ,Q715 and Q716.
No
Check if VA701,VA702,VA703,D701,R703,R704,R705 and RL701 are normal.
No
Do the primary side and secondary side of T701 oscillate normally?
Are F703,TH703,D734-D737 and
IC703 out of order?
No
Does PS_ON (pin10 of CN802) become High (approx. 3.3V)?
Check the regulator circuit of BU5V,
rectifier circuit of UR12V and RL701.
No
Do the primary side and secondary side of T701 oscillate normally?
Are D824 out of order?
PS_ON
BU5V
UR12V
(CN802
)
(CN802
10
)
11
High
5V
12V
-
Low
5V
High
5V
12V
Yes
Are there defective parts on the
primary side?Is the output on the
secondary side short-circuited?
Yes
Is the unit set to STANDBY MODE?
Is the main unit normal?
Yes
Are there defective parts on the pri-
mary side?Is the output on the Sec-
ondary side short-circuited?
UR24V
)
1
(CN801 1 )
24V
-
24V
27
LC-26D43U
No
No
No
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