Sharp LC-20AV7U Service Manual - Page 23

Flow Chart No.20, Flow Chart No.19, Flow Chart No.18

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FLOW CHART NO.18 DTV-ON+1.8V is not output. Is approximately 3.3V voltage supplied to the No cathode of D911? Yes Check IC904 and their periphery circuit, and service it if defective. FLOW CHART NO.19 PANEL-6V is not output. Is approximately -6V voltage supplied to the No anode of D931? Yes Check if there is any leak or short-circuit on the loaded circuit and service it if defective. FLOW CHART NO.20 The key operation is not functioning. Are the contact point and installation state of the key No switches (SW1101,SW1102,SW1103,SW1104, SW1105,SW1107,SW1111) normal? Yes When pressing each switches (SW1101,SW1102, SW1103,SW1104,SW1105,SW1107,SW1111) do the No voltage of each pin of CN1301 (shown below) increase? SW1101,1102,1103,1104,1105,1107 : CN1301 PIN 2 SW1111 : CN1301 PIN 1 Yes Check IC1202 and the periphery circuit, and service it if defective. Check D911, C908 and their periphery circuit, and service it if defective. Check D931, C920 and their periphery circuit, and service it if defective. Re-install the switches (SW1101,SW1102,SW1103, SW1104,SW1105,SW1107,SW1111) correctly or replace the poor switch. Check the switches (SW1101,SW1102,SW1103, SW1104,SW1105,SW1107,SW1111) and their periphery, and service it if defective. 7-6 A7144_45TS

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7-6
A7144_45TS
When pressing each switches (SW1101,SW1102,
SW1103,SW1104,SW1105,SW1107,SW1111) do the
voltage of each pin of CN1301 (shown below)
increase?
SW1101,1102,1103,1104,1105,1107 : CN1301 PIN 2
SW1111 : CN1301 PIN 1
Yes
No
The key operation is not functioning.
FLOW CHART NO.20
Are the contact point and installation state of the key
switches (SW1101,SW1102,SW1103,SW1104,
SW1105,SW1107,SW1111) normal?
Re-install the switches (SW1101,SW1102,SW1103,
SW1104,SW1105,SW1107,SW1111) correctly or
replace the poor switch.
No
Check the switches (SW1101,SW1102,SW1103,
SW1104,SW1105,SW1107,SW1111) and their
periphery, and service it if defective.
Yes
Check IC1202 and the periphery circuit, and service
it if defective.
Yes
No
PANEL-6V is not output.
FLOW CHART NO.19
Is approximately -6V voltage supplied to the
anode of D931?
Check if there is any leak or short-circuit on
the loaded circuit and service it if defective.
Check D931, C920 and their periphery circuit, and
service it if defective.
No
DTV-ON+1.8V is not output.
FLOW CHART NO.18
Is approximately 3.3V voltage supplied to the
cathode of D911?
Check IC904 and their periphery circuit,
and service it if defective.
Check D911, C908 and their periphery circuit, and
service it if defective.
Yes