LC-37XD1E/RU
4 – 1
LC-37XD1E
Service Manual
CHAPTER 4. TROUBLESHOOTING TABLE
[1] TROBLESHOOTING TABLE
Power unit operation check.
Are the power cord and har-
ness in the unit properly con-
nected ?
NO Connect the power cord
and harness properly,
and turn on the power.
YES
Is F701 normal ? NO Are both ends of C704
and C715 short-cir-
cuited when checking
their resistance values?
NO Replace F701.
YES
YES
C704 ⋅⋅⋅ Check VA701 ,
VA702 and D701.
C715 ⋅⋅⋅ Check IC704
and 705.
Is a voltage of BU5V applied
to pin (20) of P701?
(Set the main power SW to
OFF.)
NO Is a voltage of approx. 8
- 15V to pin (4) of
IC705?
NO Check IC705,
IC708, D725 and
Q724.
YES
YES
Check short circuit of 5V
line (D737, C752, etc.).
Is it a symptom that the relay
clatters twice as soon as the
main power SW is set to ON
and the power is not sup-
plied?
NO Does a relay noise
sound? (Once)
NO Are PCON1 and 2
[pins (1) and (2)
of P702] at Hi
(3V or more)?
YES
YES YES
Check peripheral cir-
cuits of D738, R828 and
D735.
Check peripheral
circuits of Q712,
Q713, Q721,
Q723 and RY701.
NO There is a possibility that control
by P-CON is not performed
properly. Check whether the
"PCON1" and "PCON2" signals
are sent from pins (A23) and
(A21) of IC3002 (V-PRO.) of
MAIN-UNIT.
Does the same symptom
appear even if R858 (2.7k) is
removed and the power is
supplied again ?
NO Check IC704, D728, D762 and D736. If there are no
problems, check the resistance value between pins (1)
and (6) of P704.
When the value is low (several Ω- several hundred Ω),
disconnect P704. If the value is still low, the parts of 24V
line are defective.
When the resistance value is several kΩ check the
inverter unit.
YES
Check Q724, D731 , D734,
IC707, D751 , D753, D754,
D741 , D759 and D746.
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