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ELECTRONIC CIRCUIT DESCRIPTION
e Over Voltage Protection Circuit
+13V
+13V
Figure 25
a. According
to the change of secondary output voltage,
the output voltage of D805 changes.
b. When the secondary output voltage increases abnormally,
the equivalent
voltage to the change is detected
from
D805, and D807 conducts.
As a result the pin 10 voltage of 1C801
increases.
c, When the pin 10 voltage of IC801
increases and exceeds
the reference voltage, the comparator turns on and the
Q809 base voltage decreases.
@
Horizontal Osc. Disable Circuit
1C5002
Figure 26
a. A pulse
from
the
FBT
is rectified
and
smoothed
by
D553 and C560.
R567 and R566 share the voltage drop.
—14—
D553
. By
the
decrease
of Q809
base
voltage,
the
emitter
current
increases causing the pin 9 voltage of IC801 to
decrease.
. By decreasing the pin 9 voltage of |1C801, the pulse width
of pin 14 becomes too narrow.
By this operation, the secondary output voltage decreases.
R534
FBT
b. If the high voltage
rises, the shared
voltage rises and
turns D555 on.
_
os
Parnes
By this, horizontal osc. disable circuit in 1C5002 turs on.
. Result of this, the frequency of the horizontal osc. rises
and it works to decrease the high voltage.
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