8-48
8-10. Power Management System Circuit
When the horizontal and vertical Sync. are missing, the voltage of CN-PM pin 2 becomes low level and Q673
turn off and Q672 turn on.
As current flows via R673, R675 and D673 into a PC621 when Q672 turns on, each output voltage starts
lowering and becomes stable. When the voltage of C671 “+” terminal (about +80V at normal output voltage),
reduced to about +11V in this event.
The stable power source for IC801 can be established by supplying C671 “+” terminal through R671 and
Q671 while Q672 in on.
This is “SUSPEND STATE” and “OFF STATE” condition.
When the horizontal and vertical Sync applies again, the voltage of CN-PM pin 2 becomes high and Q673
turns on and Q672 turns off.
At this time, each output voltage rise and becomes stable at the normal output voltage.
And “ON STATE” is achieved.
(Fig.8-10) Power Management System Circuit
+80.2V
2
CN-PM
D671
R671
ZD671
R672
Q671
D672
R674
R673
R675
C623
R676
R677
D673
C672
ZD672
C673
R678
+8.5V
IC671
PC621
Q673
Q672
2
1
3
R621
IC621
7
9
SECONDARY
PRIMARY
+
-
C671
+
-
C674
To +80.2V
secondary winding
D6E1
L6E1