TM 11-5840-360-14-1-1
3. Locate the three alignment screws in the facial
2. Using the interconnection diagram applicable to
surface of the plotter assembly housing. Using a grease
the system configuration (Figures 6.1-1 through 6.1-4),
pencil, place a dot on the glass surface of the plotter
determine which switch assembly (S1A, S1B or SC).
adjacent to each alignment screw; the dots should be
and which wafer(s) within the Switching Unit(s) control
placed approximately one inch from the edge of the
the faulty function; identify the input and output
glass surface and on the radial lines between the center
terminals of the wafer (s) for the function.
of the CRT and each alignment screw.
3. Verify that the signal or control level is correct at
4. Adjust the PNL LIGHTS control for desired
the input terminal (s). If incorrect, determine the source
brightness of the dot reflections on the face of the CRT.
equipment using the interconnection diagrams and refer
to the troubleshooting chart for that equipment.
5. View one of the dot reflections from an oblique
angle and adjust the adjacent alignment screw to cause
4. Refer to the schematic diagram for SA-2139 or
the reflection to appear in the plane of the sweep trace
SA-2156 in Section 6.5 of Chapter 6 and perform
on the face of CRT.
continuity measurements at the switch wafer (s) which
control the function to isolate the fault.
NOTE:
Clockwise adjustment will cause the
reflection to appear below the trace;
5.13.2 Removal/Replacement Procedures (V2, V3, V4)
counterclockwise adjustment will
In the event a damaged wafer or wafer terminal
cause it to appear to rise above the
is found to be the cause of the malfunction, a spare
trace.
wafer may be substituted in lieu of replacing the switch
assembly. To substitute a spare wafer for a damaged
6. Repeat step 5 for each of the remaining
one, proceed as follows:
alignment screws.
7. Place a grease pencil dot on the plotter surface
1. At the switch assembly (S1A, S1B or S1C)
at the center of the display. View the resulting reflection
containing the damaged wafer, select the spare wafer
from several angles and verify that it lies in the plane of
which is physically nearest to the damaged one. Spare
the sweep trace.
wafers for the SA-2139 and SA-2156 Switching Units
are:
5.13 SWITCHING UNITS SA-2139 (V3, V4) AND
a. SA-2139: S1A Wafers 26 and 27
SA-2156 (V2)
S1B Wafers 29 and 30
S1C Wafers 1 through 10
Switching Units SA-2139 and SA-2156
(Interswitches) are passive multi-position switching
b. SA-2156: S1A Wafers 29 and 30
assemblies which provide system mode selection
S1B Wafers 15, 16, 29 and 30
control. Radar Set AN/SPS-64(V)2 uses one Switching
S1C Wafers 7, 8 and 9
Unit SA-2156. Radar Sets AN/SPS-64(V)3 and (V) 4
each use two Switching Units SA-2139. Switching Units
2. Inspect the damaged wafer for presence of
SA-2156 and SA-2139, although electrically quite
metal straps which jumper adjacent terminals on the
different, are physically similar; the locations of major
wafer; note the terminals jumpered. Move the straps to
components and assemblies within the units are shown
the selected spare wafer and install so as to jumper the
on Figure 5-10. Schematic diagrams, parts list tables
same terminals.
and assembly drawings for both Switching Units are
3. Inspect the damaged wafer for presence of
contained in Section 6.5 of Chapter 6. Access to the
metal straps which jumper terminals of the damaged
components within either Switching Unit is obtained by
wafer to the same terminals of adjacent wafers; note the
removing the four screws on the front of the unit and
terminals and wafers jumpered. Connect jumper wires
removing the outer shell
(in lieu of the metal straps) from the terminals of the
adjacent wafers to the same terminals of the selected
5.13.1 Troubleshooting Procedure (V2, V3, V4)
spare wafer.
Troubleshooting of the SA-2139 or SA-2156
4. Inspect the damaged wafer for presence of
Switching Units should be addressed using the following
jumper wires between terminals; note the terminals
general technique:
jumpered. Move the jumper wires (one at a time) to the
selected spare wafer and connect between the noted
1. Determine the faulty function by troubleshooting
terminals.
the equipments which interface with the Switching
Unit(s) .
5-65
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