NOTE: MAIN UNIT POWER MUST BE TURNED OFF WHEN REMOVING/REPLACING MODULES AND
CIRCUIT CARDS, REPLACING FUSES OR DISCONNECTING/CONNECTING ANY INTERNAL CABLES.
The Main Unit (Fig. 1) performs all multiplexing, data processing, display formatting, alarm detection, and
keyboard processing. it consists of the following major internal circuit cards/modules: (Refer to Dwg. 23705 for the
physical locations of these sub-assemblies.)
THE PRINTED CIRCUIT BOARDS CONTAIN SOME COMPONENTS THAT ARE SENSITIVE TO STATIC
ELECTRICITY AND THEREFORE MUST BE HANDLED WITH THE PROPER PRECAUTIONS:
Hold board only by the edges and do not touch the individual components or back plane.
When storing a board, always place inside the protective bag supplied with it.
Lay boards only on a flat surface and on top of the protective bag.
Process and Display Circuit Board, (bottom board on Main Unit Door).
This contains the central processor unit which controls the overall system operation, the memory which holds the
software program and data base parameters, the video display processing and the communication link between the
Input Board and itself.
Section 2 - Page 1