Sharp LC-37XD10, Service Manual

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LC-37XD10E/RU
4 – 22
Backlight failure to light up
Do all the fluorescent tubes light up? NO Check the individual fluorescent
tubes for light-up failure. YES Replace any defective fluorescent
tube (s) with new one (s).
YES
Is the power supplied to CN7501 on
the inverter unit? NO Check the connection between power
unit and inverter unit.
YES
Is the Fuse (F7501 or F7701) fuse in
the inverter unit circuit functioning? NO Replace the blown-out Fuse (F7501
or F7701) fuse on the inverter unit.
Turn on the power again.
If the fuse gets blown out again,
check the short-circuited spot. YES Check T7501 and T7701 and their
peripheral circuits as IC7501 and
their peripheral circuits.
YES
Is the VCC power supplied to the
control IC (IC7501) on the inverter
unit? NO Check the circuit connected with the
VCC terminal on the inverter control
IC (IC7501).
YES
Has each control signal come to
CN7502?
(INV-OFL, INV-OSC, INV-STE) NO Have INV-ON, INV-BRT and PWM-
SEL signal come to P1701(LB) in the
MAIN substrate? NO Check pins (89) and (19) of IC1710
(main PWB) .
YES
Is the specified control signal input-
ted at IC7501 (INV-CTL) on the
inverter unit. NO Check the line between CN7502 and
IC (IC7501).
YES
Are the Q7501 and Q7502 transis-
ters at the primary side of T7501
functioning? NO Check the power line of IC7501, its
peripheral circuits or replace IC7501.
YES
Is the secondary circuit of T7501
functioning. NO Replace T7501 or the T75*** trans-
former for the fluorescent tubes, or
check their peripheral circuits.