Sharp LC-20AV7U Service Manual - Page 21

Flow Chart No.10, Flow Chart No.13, Flow Chart No.11, Flow Chart No.12 - power supply

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Page 21 highlights

FLOW CHART NO.10 DTV-ON+5V is not output. Is approximately 6.8V voltage supplied to the cathode of D903? Yes Is approximately 6.6V voltage supplied to the collector of Q905? No Is the voltage of base on Q905 lower than the voltage of emitter on Q905 when turning the power on? Yes Replace Q905. FLOW CHART NO.11 AL+3.3V(D) is not output. Is approximately 6.8V voltage supplied to the cathode of D903? Yes Check Q902, D920 and their periphery circuit, and service it if defective. FLOW CHART NO.12 PANEL+3.3V is not output. Is approximately 3.3V voltage supplied to the emitter of Q910? Yes Is the voltage of base on Q910 lower than the voltage of emitter on Q910 when turning the power on? Yes Replace Q910. FLOW CHART NO.13 AL+1.2V(D) is not output. Is approximately 3.3V voltage supplied to the Pin(3) of IC901? Yes Check IC901 and the periphery circuit, and service it if defective. No Check D903, C903 and their periphery circuit, and service it if defective. Yes Check Q907, D922 and their periphery circuit, and service it if defective. No Check Q906 and DTV-ON-H line, and service it if defective. No See FLOW CHART No.10 No See FLOW CHART No.11 No Check Q919 and P-ON-H line, and service it if defective. No See FLOW CHART No.11 7-4 A7144_45TS

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7-4
A7144_45TS
DTV-ON+5V is not output.
FLOW CHART NO.10
Check IC901 and the periphery circuit,
and service it if defective.
Yes
No
Is approximately 6.8V voltage supplied to the
cathode of D903?
Is approximately 6.6V voltage supplied to the
collector of Q905?
Is the voltage of base on Q905 lower than the
voltage of emitter on Q905 when turning the
power on?
Yes
Replace Q905.
No
AL+1.2V(D) is not output.
FLOW CHART NO.13
Is approximately 3.3V voltage supplied to the
Pin(3) of IC901?
AL+3.3V(D) is not output.
FLOW CHART NO.11
Is approximately 6.8V voltage supplied to the
cathode of D903?
No
Yes
Check D903, C903 and their periphery circuit, and
service it if defective.
Yes
Check Q907, D922 and their periphery circuit, and
service it if defective.
Yes
See FLOW CHART No.11
See FLOW CHART No.10
Check Q902, D920 and their periphery circuit,
and service it if defective.
No
Check Q906 and DTV-ON-H line, and
service it if defective.
Is the voltage of base on Q910 lower than the
voltage of emitter on Q910 when turning the
power on?
Yes
Replace Q910.
No
Check Q919 and P-ON-H line, and
service it if defective.
No
See FLOW CHART No.11
No
PANEL+3.3V is not output.
FLOW CHART NO.12
Is approximately 3.3V voltage supplied to the
emitter of Q910?
Yes