Panasonic EURO 4 Chassis, Техническое руководство

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16
Chapter 2 EURO 4 Supplement
Transistor Q3903 is then used to generate a parabola
signal
of approximately 5Vpp. This parabola
waveform is then fed to the cascade connected
transistors Q3907, Q3906. Here the signal is
amplified to approximately 250Vpp before being fed
to pin 4 of transformer T3901.
The D.A.F. transformer T3901 then combines both
the horizontal sync pulse mentioned earlier with the
vertical parabola waveform. This combined signal is
then output via the HV terminal to the D.A.F. input
terminal of the FBT T551 located on the E-Board.
Here the signal is added to the focus voltage of T551,
the focus voltage VF2 with the D.A.F. waveform signal
which is then supplied to the focus terminal on the
CRT.
By this method the focus voltage for the central and
outer edges of the scan undergo alteration. This
results in the focus voltage for the outer edges being
reduced compared with that of the central area of the
screen, thus increasing the focusing distance of the
beam and enhancing focus at the outer edges.