Philips 50PFL4909/F7, Service Manual, Page: 25 / 60

8-1 PL14.24ATR
TROUBLESHOOTING
[Power Supply Section]
When buzz sound can be heard in the periphery of power circuit.
FLOW CHART NO.4
Check if there is any short-circuit on the rectifying diode and the circuit in each rectifying circuit of the secondary side.
Repair it if defective. (D650, D653, D655, Q703, Q705)
The power cannot be turned on.
The fuse blows out.
FLOW CHART NO.1
FLOW CHART NO.2
Is normal state restored when once unplugged
power cord is plugged again after several seconds?
Check if there is any leak or short-circuit on the
primary circuit component and repair it if defective.
(C625, C665, D601, D602, D603, D604, D605, D606,
D607, D613, D618, D621A, D623, D664A, IC601,
IC604, Q601, Q602, Q603, T601, R630, R631)
Yes
No
Yes
Is the fuse (F602) normal? See FLOW CHART No.2 <The fuse blows out.>
No
Yes
Is the P-ON+21V line voltage normal?
No
Check each rectifying circuit of the secondary
circuit and repair it if defective.
Check if there is any leak or short-circuit on the
primary circuit component and repair it if defective. Check if there is any leak or short-circuit on the
each rectifying circuit component of secondary side
and repair it if defective.
Make sure to repair the primary circuit component before replacing the fuse(F602).
When the output voltage fluctuates.
FLOW CHART NO.3
Does the photocoupler circuit on the
secondary side operate normally?
No
Yes
Check IC602, D660 and their periphery circuit.
Repair it if defective.
Check D609A, D613, D614, D615, D619A, D620A,
D621A, Q601, Q602, IC602 and their periphery circuit.
Repair it if defective.