Section VIII
TM 11-6625-2781-14&P-2
indiv idual schematics by an asterisk. The recommended
8-52.
Diagram Notes.
Figure 8-17, Schematic
procedure for replacing a factory-selected part is as
Diagram Notes, prov ides information relative to symbols
follows:
and measurement units shown in schematic diagrams.
a. Try the original value, then perform the
8-53. SWITCHING INFORMATION
calibration test specified for the circuit in the
performance and adjustment sections of this manual.
8-54.
The manner in which switch wafers are
b. If calibration cannot be accomplished, try the
schematically presented in this manual is distinctly
typical value shown in the parts list and repeat the test.
different from that used in prev ious Hewlett-Packard
c. If calibration still cannot be accomplished,
manuals. If the following information concerning the
perform the calibration test using various values until
evolution of this system of switch presentation is
calibration is accomplished.
carefully studied, it will be seen that circuits are more
easily understood and much more easily traced.
8-47. Wiring Diagram. Due to the complexity of the
system it is not practical to prov ide an overall schematic
8-55. One of the major objections to drawing switch
diagram. However, Figure 8-23 prov ides overall wiring
wafer symbols as the wafer appears is that many lines
information (except for dc voltages) for all switches and
must cross other lines on the schematics. This problem
assemblies.
has not been completely eliminated by use of straight-
line presentation, but it has been minimized and circuits
8-48. DELETED.
are much easier to follow once the basic principles are
understood.
line switch presentation from the pictorial v iew of a
switch wafer. Part A shows the wafer as it actually
appears. In parts B and C, when the wafer is v iewed as
being a flexible, stretchable material, the transition from
wafer to straight-line presentation begins to be obv ious.
In part D the transition is complete and the wafer now
appears to be a slide type switch. In part E the final
result is shown. Note that those contacts which maintain
contact with the metallic portion of the rotor regardless
of switch position (in the illustration contact 7) are
moved to the other side for clarification. Note too that
lead lines and arrows to switch contacts are no longer
required.
8-49. System Test and Troubleshooting Procedure.
8-57. In all schematics in this manual the switches,
unless otherwise noted, are shown in the maximum
isolate the causes of a malfunction to a circuit or
CCW position. The physical layouts of the switches are
assembly, or to the Display Section.
shown as well as a straight-line presentation of switch
action. It is important to note that in the straight-line
8-50. No attempt is made in this procedure to isolate
presentation, the portion of a rotor mating with the
causes of trouble to the component level. Reference is
bottom contact of a switch mates with the top contact of
made to the specific Serv ice Sheet which describes the
the switch when the switch is turned one step in the
circuits and test procedures for the portion of the
clockwise direction. Switch wafer S1-1F (P/O INPUT
analyzer to which the malfunction has been isolated.
ATTENUATION assembly A3) is illustrated in three
positions to demonstrate switch action (see Figure 8-15).
Where Display Section maintenance is indicated refer to
the Display Section Operating and Serv ice Manual.
old method of switch presentation and the straight line
8-51. Dial Restringing Procedure. An illustrated dial
presentation.
The example chosen represents the
restringing procedure is prov ided in Figure 8-13.
INPUT ATTENUATION switch S1.
8-10
