Agilent Technologies 66000A, Service Manual, Page: 39 / 53

Diagrams 39
6
Diagrams
This chapter contains a test point and component location diagram and schematics for troubleshooting the Agilent 66000A
MPS Mainframe. An exploded view diagram of the mechanical parts is also provided.
Test Point and Component Location Diagram
The test point and component location diagram identifies the location of the test points that are used in the troubleshooting
procedures of Chapter 4, and are also shown on the schematic diagrams.
The test point and locations diagram also identifies all electrical components on the Main board. The diagram is divided
into columns and rows designated "x coordinates" and "y coordinates". The accompanying table lists all of the components
on the Main board and gives the coordinate location of each component. For example, resistor R154 is located at x
coordinate 12.3 and y coordinate 3.3. Refer to Chapter 5 for the part number and description of each electrical part.
Main Board Schematics
SHOCK HAZARD When servicing the Main assembly and Backplane assembly, ac line voltages are
present on the Main board and backplane connectors.
Three foldout sheets comprise the Main board schematic diagrams. The circuit functions of each schematic sheet are given
as follows:
Sheet 1 Circuit Functions
Among the circuit components included on Sheet 1 are: microprocessor U44, GPIB interface chips U15 and U17, ROM
chip U51, RAM chip U52, keyboard input J119 and J126, serial link input/output J114, and address switch S7.
The GPIB interface is the link between the mainframe and the system controller. The keyboard input is the link between the
mainframe and the Agilent 66001A keyboard. All communication between the mainframe and the controller or keyboard is
processed by U44. Data communication between the modules and the controller is also directed through U44.
Switch S7 determines the address of the mainframe. It also indicates if the mainframe is directly connected to the GPIB, or
linked to another mainframe. During troubleshooting, switch S7 is used to select diagnostic tests for troubleshooting. Pins
on test header J5 must be jumpered to perform certain diagnostic tests.
Sheet 2 Circuit Functions
Among the circuits included on Sheet 1 are: rectifier diodes D26, D30-D32, filter capacitor C85, FET switches Q5 and Q6,
power transformer T1, bias transformer F2, FET pulse control chip U1, and pulse transformer T3. Isolation between the ac
input and the digital circuit is provided by T1 and opto-isolator U2.