Model 7002Switch System Instruction Manual - Advanced Test ...

Theory of Operationµ DINConnectorTriggerLinkIN6TTL Outputlinesto/ from µ processor(U110)ically performs many bus control, data I/O, and handshakingfunctions, thus minimizing overhead to the system microprocessors.Bus drive capabilities are provided by a 75161 and75160 (U101 and U102). The 75161 supports bus managementand handshake lines, while the 75160 drives the datalines.µ DINConnectorTriggerLinkOUT66.9 Power suppliesThe Model 7002 uses two identical AC-input switching powersupplies. Each supply can provide regulated +6VDC and+14.6VDC. Each supply has an internal line fuse and automaticallyadjusts to the voltage of the AC line power.Figure 6-9Trigger linkDB-9ConnectorDigitalI/OOutput4Pull up VoltageInput2596DigitalI/OOutputDriversControl lines To µprocessor(U110)AC line power is routed through the digital board to thePOWER switch, which is also on the digital board. Two 5Afuses (F100 and F101) are used to protect the digital boardfrom damage in the event that the AC line power becomesshorted. The AC line power is then routed to the two powersupply boards.One power supply is routed to the backplane and is used toprovide +6V and +14.6V for the relay power supply circuitry.Figure 6-10Digital I/O6.8 IEEE-488 interfaceThe +6V of the other power supply is used to drive the LEDs.On the digital board, the +6V is regulated to +5V using threeLM2940 regulators. One +5V supply is used by the VFDmodule (U118) to generate +60VDC and 5VAC for the VFDdisplay. All other digital board circuitry is powered by theother +5V supply. The third +5V supply powers the backplane+5V card slots.The IEEE-488 interface is composed of three ICs. A 9914(U104) General-Purpose Interface Adapter (GPIA) automat-6-11