Agilent Technologies 2948, 2712A manual A2 Digital Assembly, General

Model 8904A Service

A2 DIGITAL ASSEMBLY

General

The A2 Digital Assembly creates the output waveforms as a series of digital codes (via its DWSIC) and performs the overall control and functioning of the instrument (via its microprocessor). Specific tasks include

econtrol the instrument’s general operation e create the digital waveforms

e distribute waveform data to the proper output

e control the programmable analog circuits (attenuators, filters, etc.) e retain instrument settings in RAM

e backup RAM at power down

e process keyboard, HP-IB, digital port, and overvoltage interrupts 0 scan the keyboard when a key press is detected

e interface with HP-IB

e generate the reference clocks

e switch between internal and external references e control the beeper

e generate and time the display backlight

e control the front-panel displays and annunciators e output waveform data to the digital port

Because some circuits on the assembly are proprietary and because the assembly is available as an exchange assembly, a schematic diagram with detailed theory and troubleshooting has not been provided. Troubleshooting procedures to isolate a fault to the assembly can be found in the troubleshooting section of this manual.

Principles of Operation (A2) 8-23