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·SECTION 3
CIRCUIT DESCRIPTION
3.1
GENERAL DESCRIPTION
The model c-6919 Color Monitor is a 19V" high-resolution
RGB Monitor.
A simplified block diagram is shown in Fig.
5-1.
The design relies on a superfine pitch shadow mask
CRT to achieve a high-resolution color display.
The
number of apertures in the shadow mask is four times
greater than domestic color-TV CRTs.
Spacing between
triads is approximately 0.31 mm.
This superfine pitch
shadow mask is complimented by a small aperture precision
IN-LINE gun assembly providing small spot size.
This fine spacing enhances the display quality by mini-
mizing display granularity.
The supporting electronics,
including the deflection amplifiers, video amplifiers,
power supply regulation and noise rejection, dynamic
focus circuit, have been optimized to complement the
capability of the high-resolution shadow mask CRT.
The monitor is designed to accept video signals conform-
ing to the EIA standard RS-170 and RS-343 format.
Provision is made to accept three separate video inputs;
red, green and blue.
Two BNC connectors are provided for
each input to permit "loop through" operation.
Each video input has on associated switch which can select
either high impedance, or 75 ohm termination.
Video
inputs are applied to three buffer amplifiers, located
on the PCB-VIDEO-SUB.
These buffer amplifiers drive
three video amplifiers through Gain and Contrast
controls.
The outputs of the video amplifiers drive their respec-
tive CRT cathodes.
Each video amplifier contains a de
restorer circuit which is called a backporch clamp.
The de level of each video amplifier output is clamped
during the backporch interval.
3-1
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