Nokia 447ZiPlus Service Manual page 13

17” colour monitor
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thereby blocking the power output, the voltage at pin7 of I862 then decrease to below 10V, I862 is forced off.
However, in order to allow auto-recovery from power saving off state, the SMPS circuit is designed as an
unlatched type, the DC current flows via R849 Q850, R850 to charge C866A again, when the voltage across
C866A has reached 16V, I862 is turned on again. Once the peak voltage across R867 is over 1Vp-p, I862
will be forced off again.
Consequently, when short circuit or overload occurred, I862 is turned on and off repeatedly, and the power
will not be switched off, Q868 and R808 may be over stressed and fail.
6-2 Power Management Circuit
There are three modes of indicator in this power LED described as below, the first mode, "green-
indicator " indicates the normal state; "yellow-indicator" indicates the stand-by and the suspend
state. The third mode, " amber-indicator " indicates the power saving off state. Both H. sync and V.
sync are off.
I501
#40
V
MODE
NORMAL
STAND BY
SUSPEND
OFF
When the display signal enters the "suspend " state of power saving, which is V. sync off, the voltage at
pin31 of I501 is low, Q821 is OFF, and Q820 is OFF too. this will shut down the oscillation of the horizontal
and vertical deflection , the power saving is then achieved.
#39
#31
H
1
1
1
1
0
0
0
1
0
0
0
0
#29
D862
LED
1
GREEN
1
YELLOW
1
YELLOW
0
AMBER
11

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