NEC FP1355 Service Manual page 34

After the horizontal and vertical DBF
voltage are separately generated, they are
amplified and are finally composed.
<Horizontal section>
The voltage (approx. 0.5Vp-p) of the pa-
rabola waveform shown in Fig. (a) is output
from the deflection processor IC (IC601),
and is amplified approx. 10 times by OP-
AMP (IC6A2). Thereafter, it is amplified to
50 to 60Vp-p by the transistor (Q7B1 and
Q7B2). The amplification ratio is deter-
mined by the ratio between the resistors
R7B6 and R7B7, being approx. 10 times.
Moreover, the waveform is reversed as
shown in Fig. (b) at this time. Then, it is
amplified to approx. 500Vp-p by DBF
transformer (T7A1). The coil ratio between
the primary and secondary coils of the DBF
transformer is 1: 10, being the amplifica-
tion ratio of approx. 10 times.
<Vertical section>
The voltage (approx. 1.0Vp-p) of the pa-
rabola waveform shown in Fig. (a) is output
from the deflection processor IC (IC601),
and is amplified approx. 4 times by OP-
AMP (IC6A2). Thereafter, it is amplified to
approx. 160Vp-p by the transistor (Q7A1).
The amplification ratio this time is deter-
mined by the ratio between R7A3 and
R7A4, being approx. 40 times.
The horizontal and vertical DBF voltages
amplified and reversed are composed by
applying vertically synchronous modulation
to the output on the secondary side as
shown in Fig. (c). The composed voltage
is input to Pin 12 of the flyback transformer
(T701).
Figure (a)
Figure (b)
Figure (c)
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Vertical DBF
Horizontal DBF
Horizontal period
Vertical period