Troubleshooting Follow Chart; Troubleshooting Flow Chart - Nokia 447ZiPlus Service Manual

8. TROUBLESHOOTING FLOW CHART

(1) Power Start NG
F801
open ?
Check power socket copper and
plug & D811...D814, R805
Check R849, R848, D870, C831,
D831, R831,Q850
No
Is
Yes
Replace
F801
No
No
Q820,Q821,Q822,
Q823 and their input
control logic
Power start NG
Is the
voltage at
C815 normal
(125-340V)
?
Yes
Does
R808
open?
No
Check Q868,I862,D831,R867
Is the
start-up
voltage at
C831(16V)
?
Yes
Is the
voltage of
R867 normal
(>1Vpp)?
Check secondary side circuit.
No
D802~D807 or any short circuit
on B+ output,R867 resistance
27
Yes
Yes