Repair manual

2-54
THEORY OF OPERATION
If it is determined that the filter wheel is positioned correctly
(specified colored filter between monitor display screen and the
selected camera), the microprocessor network stops sending filter
wheel position output data to the stepper motor drive network.
The stepper motor stops, leaving the filter wheel with the specified
colored filter in front of the monitor display screen.
Once the specified colored filter is placed between the monitor
display screen and the selected camera, the exposure for the
selected colored filter takes place. The image data for the
specified colored filter that was downloaded into the dynamic
buffer memory (DRAM) and then subsequently into the video
buffer memory (VRAM) gets processed by the Video Signal
Generation Control network.
Upon command, parallel image data in the video buffer memory is
read from the VRAM shift registers and then applied to the latch in
the Video Signal Generation Control network. This circuit
serializes the parallel image data into a VIDEO image signal.
The Video Signal Generation Control circuit applies the VIDEO
image signal via connector J9 to the input of the Cathode Driver
network on the Monitor P.C. Board. The monitor display screen
turns on, exposing the film to the video image. At the end of each
exposure sequence, the VIDEO image signal is inhibited, causing
the monitor display screen turn off. Once the parallel image data
has been exposed, the Digital Palette repeats the exposure cycle
using a different colored filter. This action is repeated until the
entire sequential exposure is completed.
Note
If the next Expose Color command specifies a colored filter
number higher than the previous filter position, the filter
wheel rotates directly to it.
If the next Expose Color command specifies a colored filter
number lower than the previous filter position, the filter
wheel rotates to its home (start) position and then goes to its
specified position.
Refer to paragraph 5 in this Section of the Service Manual for a
functional description of the Video Signal Generation Control
Network.