Sharp LC-37XD1E Service Manual page 53

Do all the fluorescent tubes light up?
YES
Is the power supplied to CN1 and
CN2 on the inverter unit?
YES
Iis the Fuse (F201, F401, F251 or
F451) fuse in the inverter unit circuit
functioning?
YES
Is the VCC power supplied to the
control IC (U4) on the inverter unit?
YES
Has each control signal come to
CN1?
(INV-ON, INV-BRT and PWM-SEL)
YES
Is the specified control signal input-
ted at IC (U4) (INV-CTL) on the
inverter unit.
YES
Are the Q23 ,Q25, Q24 and Q26
transisters at the primary side of
T201 functioning?
YES
Is the secondary circuit of T201 func-
tioning.
Backlight failure to light up
NO Check the individual fluorescent
tubes for light-up failure.
NO Check the connection between power
unit and inverter unit.
NO Replace the blown-out Fuse (F201,
F401, F251 or F451) fuse on the
inverter unit. Turn on the power again.
If the fuse gets blown out again,
check the short-circuited spot.
NO Check the circuit connected with the
VCC terminal on the inverter control
IC (U4).
NO Have INV-ON, INV-BRT and PWM-
SEL signal come to SC1702(PB) in
the MAIN substrate?
NO Check the line between CN1 and IC
(U4).
NO Check the power line of IC (U4), its
peripheral circuits or replace IC (U4).
NO Replace T201 or the T*** transformer
for the fluorescent tubes, or check
their peripheral circuits.
4 – 22
LC-37XD1E/RU
YES Replace any defective fluorescent
tube (s) with new one (s).
YES Check T201, T403, T251 and T453
and their peripheral circuits as
IC7502B and their peripheral cir-
cuits.
NO Check pins (89) and (19) of IC1710
(main PWB) .