Service manual

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6
Diagrams
Introduction
This chapter contains the test point and component location diagram, schematic diagrams, and related tables useful for
maintenance of the electronic load mainframe. Similar information for each model of plug-in load module is provided in the
module service manuals. Ordinarily, maintenance is done with both a mainframe and at least one module, so the module
service manuals should be available for use with this manual.
Test Point and Component Locations
Figure 6-2 is an assembly drawing of the GPIB Board assembly which shows the location of test points and components on
the GPIB Board. The test points are described in Table 3-3, and are used in various troubleshooting procedures provided in
Chapter 3.
Figure 6-2 includes a grid by which components can be located on the assembly. Table 6-2 is an alphanumeric listing of
each of the electrical components on the GPIB Board assembly. The coordinates listed for each component give the location
(to within 1/10 of a unit) for one pin of that component (pin 1 if numbered).
For example, R244 (located near the upper left corner of Figure 6-2) has coordinates listed in Table 6-2 of 1.2 and - 5.0.
Looking at Figure 6-2, you can see that one pin of R244 is located on the -5 coordinate, 2/10 of the way between
coordinates 1 and 2.
For another example, U227 (located near the center of the board) has coordinates of 6.0 and -3.7. Looking at Figure 6-2,
you can see that pin 1 of U227 is located on the 6 coordinate, 7/10 of the way between coordinates - 3 and - 4. Table 5-4
gives the part number and description of each electrical part.
Schematic Diagram
Figure 6-1 shows the connections between the GPIB Board and the front-panel-mounted keypad. Figure 6-3 is the schematic
diagram of the Electronic Load mainframe. Notes that apply to all of the schematic sheets are given in Table 6-3. Most of
the electrical components are mounted on the GPIB Board, with exceptions noted on the schematic. The Agilent 6050A and
6051A are electrically identical except that the Model 6051A has only one fan. The block diagram description in Chapter 4
provides a general description of circuit operation.
Signal Descriptions
Table 6-1 lists, alphabetically, all the signal names that appear on the schematic, along with a brief description of the
signal's function. To help you locate where signals come from and go to, Table 6-1 lists the coordinates for each appearance
of a signal on each sheet of the schematic. Coordinates printed in bold indicate the signal origin.
For example, when CAL_LOCK is active it locks out software calibration. CAL_LOCK originates in area 8C of sheet 1,
and it also appears in area 4A of sheet 3.