Repair manual

2-56
THEORY OF OPERATION
E. Monitor Assembly
The Monitor Assembly used in the Digital Palette is basically a medium resolution
black-and-white television. It consists of a rectangular Cathode Ray Tube (CRT) and a
Monitor P.C. Board. The Monitor P.C. Board contains a flyback transformer and the
electronic circuits required to drive the CRT.
The parallel interface port on the rear of the Digital Palette accepts a computer-generated
image from the host computer. The Logic Controller P.C. Board processes this
computer-generated image into a video signal. Electrical circuits in the Monitor
Assembly process the digital video signal into a medium resolution video image which is
displayed by the CRT.
Upn command from the host computer, the microprocessor control circuitry on the
Logic Controller P.C. Board explained in Section D of this Service Manual exposes the
video image processed by the Monitor P.C. board through selected colored filters,
resulting in a colored slide or print of the video image.
The electronic circuits that make-up the Monitor P.C. Board are:
o Controls
o Cathode Ray Tube
o DC Power
o CRT Power
o Cathode Driver
o Horizontal Deflection
o Vertical Deflection
o Luminance (Brightness)
o COS4 Exposure Correction
Figure 2-5 shows a simplified block diagram of the Monitor P.C. Board. Refer to the
Monitor P.C Board schematic (Figure 2-10) in Section G of this Service Manual for a
detailed diagram of the electrical circuits on the Monitor P.C. Board. While reading the
following functional descriptions of the circuits that make-up the Monitor P.C. Board
refer to both diagrams.
1. Controls
The controls on the Monitor P.C. Board provide the adjustments needed to
properly size and align (horizontally and vertically) the CRT video display.
Table 2-12 lists each control by its assigned name and component number. It also
explains their function.