Sigma BM-286A service manual Theory of Operation

4. THEORY OF OPERATION page 31

4.2.5. Discriminator Card, RCS-120:

Refer to "RCS-120 Schematic Diagram" Drawing 8 and "RCS-120 Component Designator" Drawing 9 (Appendix F.).

The ±15 volt power supply voltages are regulated to ±12 volts and +5 volts used on this card. The card is lined with test points for measurement of the discriminator levels.

U7 generates the negative 10 volt reference used by the serial digital to analog voltage converters (U1,5,8,10). The converters are selected by the computer through the CIF-553 via U3; a programmable gate array. Serial data and clock are also generated by the CIF differential drivers and U4 receiver decodes this information. Voltage outputs from the converters go to operational amplifiers and transistor drivers to each RCS-110 card by the 44 edge card connector.

4.2.6. Computer Interface Board, CIF-553:

Refer to "CIF-553 Schematic Diagram" Drawing 17 and "CIF-553 Component Designator" Drawing 18 (Appendix F.).

This board is located in the DOS machine. TSA Systems manufactures the CIF-553 board for use in their PC based products. The CIF-553 has the following characteristics:

•Twenty-one - 16 bit counters

•Three - 8 bit I/O ports

•Twenty-four - differential line receivers

•Four - differential line transmitters

•Two - ribbon connectors (50 & 34 pin)

which interface with the backplane (RCS- 130)

•The counters are used for the radiation detectors, motor encoders, etc.

•The ports are used for system control and discriminator setting.

•Port "C" has 4 differential line drivers and line receivers.

•The Address of the card is 1000.

Model BM-286A