Read Sharp BD-HP21H (serv.man2) Service Manual online
BD-HP21U/S/H/A/X/RU/SB,BD-HP50U/X
2 – 10
The LCD backlight fails to light up.
Is the "H" voltage applied at the non-base-connected side of
Q1107 on R1138?
Q1107 on R1138?
NO
NO
Check the pattern between pin (13) of SC1101 and R1138.
Is the "H" potential outputted from pin (40) (LED_BL_LCD) of
IC2504?
IC2504?
Check IC2504 and its peripheral circuits.
Or replace IC2504 as required.
Or replace IC2504 as required.
Check the line between pin (40) of IC2504 and pin (9) of SC2501.
YES
Is the "H" potential applied at pin (13) (BL_LCD) of SC1101?
YES
Check Q1107, LED and the current-limiting resistor.
YES
NO
Is the "H" potential applied at pin (9) (BL_LCD) of SC2501?
Check the FFC between SC1101 and SC2501.
YES
NO
FLOW CHART No.3
The LED power indicator fails to light up.
Is the power as specified?
YES
NO
Check each transistor, LED and the current-limiting resistor.
Is there the "H" potential at pin (18) (LED_STBY) or pin (17)
(LED_PON) of SC2501?
(LED_PON) of SC2501?
Is the "H" potential outputted from pin (53) (LED_STBY) or pin
(51) (LED_PON) of IC2504?
(51) (LED_PON) of IC2504?
Check the FFC between SC1101 and SC2501.
YES
Check the line between IC2504 and SC2501.
YES
Is the "H" potential applied at the base of Q1111 or Q1112?
YES
POWER FLOW CHART No.1 or POWER FLOW CHART No.3
NO
NO
Check IC2504 and its peripheral circuits. Or replace IC2504 as
required.
required.
NO
Is there the "H" potential at pin (4) (LED_STBY) or pin (5)
(LED_PON) of SC1101?
(LED_PON) of SC1101?
Check the line between SC1101 and the base of each transistor.
YES
NO
FLOW CHART No.4
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