Read Sharp BD-HP21H (serv.man2) Service Manual online
BD-HP21U/S/H/A/X/RU/SB,BD-HP50U/X
2 – 15
The LCD backlight fails to light up.
Is the "H" voltage applied at the non-base-connected side of
Q1108 on R1123?
Q1108 on R1123?
NO
NO
Check the pattern between pin (7) of SC1101 and R1123.
Is the "H" potential outputted from pin (40) (LED_BL_LCD)
of IC2504?
of IC2504?
Check IC2504 and its peripheral circuits. Or replace IC2504
as required.
as required.
Check the line between pin (40) of IC2504 and pin (7) of P2502.
YES
Is the "H" potential applied at pin (7) (BL_LCD) of SC1101?
YES
Check Q1107, LED and the current-limiting resistor.
YES
NO
Is the "H" potential applied at pin (7) (BL_LCD) of P2502?
Check the connection between SC1101 and P2502.
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 (2) (LED_STBY) or pin (1)
(LED_PON) of P2503?
(LED_PON) of P2503?
Is the "H" potential outputted from pin (53) (LED_STBY) or pin
(51) (LED_PON) of IC2504?
(51) (LED_PON) of IC2504?
Check the connection between SC1102 and P2503.
YES
Check the line between IC2504 and P2503.
YES
Is the "H" potential applied at the base of Q1106 or Q1107?
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.
as required.
NO
Is there the "H" potential at pin (2) (LED_STBY) or pin (1)
(LED_PON) of SC1102?
(LED_PON) of SC1102?
Check the line between SC1102 and the base of each transistor.
YES
NO
FLOW CHART No.4
Click on the first or last page to see other BD-HP21H (serv.man2) service manuals if exist.