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4
Diagrams
Schematic Diagrams
Schematic diagrams and component location diagrams are provided for the Control board as well as the Power board on two
foldout pages. Two schematic diagrams of the Power board are included in Figure 4-2 on the first foldout; three schematic
diagrams of the Control board are included in Figure 4-4 on the second foldout. Table 4-1 lists the notes that apply to both
the Control board and Power board schematic diagrams.
Table 4-2 lists, alphabetically, all of 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 4-1 lists the coordinates for each appearance
of a signal on each sheet of the schematic. Coordinates printed in BOLD indicate the signal origin. On the Control board for
example, when ACLR* is active, it clears the analog circuits. ACLR* originates in area 4D of sheet 1 and also appears in
area 2B of sheet 3.
Table 4-1. Schematic Diagram Notes
1. All resistors are in ohms ± 1%, 1/8 W unless otherwise specified.
2. All capacitors are in microfarads unless otherwise specified.
3. All unmarked capacitors are 0.047µF.
4. An asterisk negates a signal name. For example,
CS2
appears on the schematic as CS2*.
5. Signal lines that are terminated by flags continue on other sheets, and may also go to other locations on the same sheet.
Table 4-2 documents all signal terminations on the schematics. Note that flags do not indicate signal flow direction.
Example: CC_PROG
6. Unterminated signal lines go to at least one other location of the same schematic sheet.
Example: SPCLR*
7. Heavy signal lines represent multiple-wire data buses.
8. Unless otherwise noted, bias connections to IC packages are as follows:
Common +5V
14-pin packages pin 7 pin 14
16-pin packages pin 8 pin 16
20-pin packages pin 10 pin 20
9. Values in brackets [ ] apply to model 60501B.
Component Location Diagrams
Each foldout includes a component locations diagram with a look-up table for locating electrical components. Figure 4-1
gives the component locations for the Control board and Figure 4-3 gives the component locations for the Power board. The
coordinates in the look-up table under each diagram reference the grid on the diagram and give the location of some point
on each component to within 1/10 of a unit. The mainframe Service Manual gives several examples of how to use the table.
The component locations diagram also indicates specific troubleshooting test point locations. The test points are described
in Chapter 3 of the mainframe Service Manual and are used in various troubleshooting procedures described in that chapter.