Read Sharp LC-26D44E (serv.man5) Service Manual online
LC-26D44E/S/RU-BK/GY
4 – 2
The backlight does not light
Are all fluorescent lamps on?
NO
Check each fluorescent lamp, and replace if defective.
(CN7501-9, etc.)
(CN7501-9, etc.)
NO
Is 38V applied to both ends of C7500/C7501?
NO
Refer to "No power supply (Front LED does not light up)" and "No
power-up even if turned on (Front LED light up)".
power-up even if turned on (Front LED light up)".
YES
Is F7500 normal?
NO
Check if the peripheral circuits are short-circuited or parts are faulty.
(L7500, MOS7500-3, etc.)
(L7500, MOS7500-3, etc.)
YES
Is IC12V supplied from the collector side of Q7501?
NO
Check if the STB_ON/OFF signal sent from PIN(2) of connector
CN7502. (Q7501-2, Q7508, Q7510, etc.)
CN7502. (Q7501-2, Q7508, Q7510, etc.)
YES
Is a voltage of 5V applied to PIN(5) of IC7500?
NO
Does the regulator circuit normally work?
(Check Q7503, U7500, etc. and the peripheral circuits.)
(Check Q7503, U7500, etc. and the peripheral circuits.)
YES
Does each control signal of connector CN7502 normally
function?
function?
NO
Check each control circuit.
PIN(3) OFL1 (PWM light control signal input)
OFL (PWM light control signal input)/H: Lamp ON, L: Lamp OFF
PIN(5) ERR (Error output)
ERR (Error output)/H: Normal, L: Error
PIN(7) REG2 (Light control method identification)
REG2 Light control method identification)/H: External PWM input, L:
Analog voltage input
Analog voltage input
YES
Is [0] displayed as the number of [LAMP_ERROR] in the
process mode?
process mode?
NO
Reset the number of [LAMP_ERROR] to the default value in the pro-
cess mode?
cess mode?
YES
Is the drive signal sent from PIN(19, 20)/(PDRV_A,
NDRV_B and PIN(12, 11)/ (RDR_C, NDRV_D) of IC7500?
NDRV_B and PIN(12, 11)/ (RDR_C, NDRV_D) of IC7500?
NO
Check IC7500 and the peripheral circuits.
YES
Does the drive output circuit normally work?
NO
Check MOS7500-3, etc. and the peripheral circuits.
YES
Does the secondary side of T7500-4 normally work?
NO
Check T7500-4, D7523-7, etc. and the peripheral circuits.
YES
Check the feedback circuits such as FB_LINE,
FBK_LINE, FB_1_LINE, OVP_LINE.
FBK_LINE, FB_1_LINE, OVP_LINE.
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