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DIDS-402-2AMI3
The deflection voltag'es applied to the deflection yoke are developed by
circuits on Vertical and Horizontal Deflection Amplifier Assembly A2 and
Monoscope Deflection Amplifier Assembly A3.
The operation of these circuits
is described in the following text.
116.026
MS
1.-----.
'-----u--
VERTICAL
V DRIVE
_ _ _ _ _ _ _ _
1
DEFLECTION
----....,~
(FROM TIMING) ..
AMPLIFIER
1------------.
H DRIVE
(FROM TIMING)
DIDS 68-52
J
-1
r--
I. 144 MS
11111111111111
PjOA2
SKEW
HORIZONTAL
~
DEFLECTION
- - - - - - - - - 1
AMPLIFIER
P/O A2
A
... ;LT
__
==
z:
(=
::
VERTICAL
RETRACE
SOLID LINES DENOTE VISIBLE SO
DOTTED LINES DENOTE RETRACE
Figure 4-22.
Vertical and Horizontal Deflection Amplifier,
Block Diagram
4-19. 1 Vertical and Horizontal Amplifie r Assembly A2
The purpose of this assembly is to develop skew-corrected vertical and
horizontal deflection voltage s for displaying 13 horizontal liI\e s on the CRT
screen.
The circuits are interconnected and operate in conjunction to produce
the desired visible effect.
For example, if the vertical deflection amplifier was
inoperative, only one intense horizontal line would be displayed across the center
of the ,CRT screen.
Conversely, if the horizontal deflection voltages were
absent, an intense horizontal line would: be displayed vertically at the center of
the screen.
4-19. 1. 1 Horizontal Deflection Ampline r
The horizontal deflection amplifier (figure 4-22) receives a horizontal
drive pulse from the character counter of the timing circuitry.
This pulse,
which is active for 80 character times and inactive for 8 character times, is
converted to a sawtooth waveform by a waveshaping network in the amplifier.
During the active line time, the sawtooth gradually increases in value and moves
the electron beam across the screen (from left to right).
At the end of 80
character times, the sawtooth rapidly collapses when the horizontal character
retrace portion of the pulse occurs.
This collapse allows the electron beam
to return to the original position on the left side of the screen.
However, since
a vertical force was also exerted on the beam as it swept across the screen, the
beam begins its second horizontal excursion one line below the previous line.
The CRT protect circuit is enabled during retrace and effectively grounds the
CR T control grid.
This halts CRT conduction during retrace and thus pr ovide s
some measure of protection for the CRT phosphor material.
4-49
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