Philips 42PFL3704D/F7 - AL+5 V Is Not Output; AL+3.3 V Is Not Output; When the Output Voltage Fluctuates; When Buzz Sound Can be Heard in the Vicinity of Power Circuit

8-2 A91H2TR
Check if there is any leak or short-circuit on the loaded
circuit, and service it if defective.
AL+5V is not output.
FLOW CHART NO.5
Is approximately +5V voltage supplied to the
cathode of D1101?
No
Ye s
Check C1103, D1101, D1102 and their periphery
circuit, and service it if defective.
Check D632, R640 and their periphery circuit, and
service it if defective.
TUNER+31V is not output.
FLOW CHART NO.9
Is approximately +40V voltage supplied to the
cathode of D618?
No
Ye s
Check C617, D618, D619 and their periphery
circuit, and service it if defective.
Is approximately +4V voltage supplied to the base
of Q1101?
AL+3.3V is not output.
FLOW CHART NO.6
Is approximately +5V voltage supplied to the collector
of Q1101?
No
Ye s
Replace Q1101.
Ye s
Check C1103, D1101, D1102 and their periphery
circuit, and service it if defective.
No
Check D1109 and their periphery circuit, and
service it if defective.
( Jack Power CBA )
When the output voltage fluctuates.
FLOW CHART NO.7
Does the photocoupler circuit on the
secondary side operate normally?
No
Ye s
Check D616, D637, IC601 and their periphery
circuit, and service it if defective.
When buzz sound can be heard in the vicinity of power circuit.
FLOW CHART NO.8
Check if there is any short-circuit on the rectifying diode and the circuit
in each rectifying circuit of the secondary side,
and service it if defective. (D613, D615, D617, D618, D620, D621, D622, D623, D624, IC602, Q603, Q604, Q605)
Check D607, IC601 and their per
iphery, circuit and
service it if defective.