CHAPTER 3
FIFTH ECHELON MAINTENANCE
Section I. TROUBLESHOOTING AND REPAIR
53. General
minals by other plug-in as-
semblies.
This chapter includes troubleshooting
(2) In addition to the listed test equip-
and repair procedures to be performed
ment, cables No. 10 and 11 (fig.
by fifth echelon maintenance facilities. It
includes detailed isolation, replacement,
(3) When the frequency of a signal
and adjustment data for the plug-in as-
generator is specified without an
semblies. Chapter 4 includes fifth echelon
accompanying tolerance, set the
final testing procedures.
frequency to the number of signi-
cant figures expressed. For ex-
54. Plug-In Assembly Repair Procedures
ample, 11.500 mc is set to an ac-
curacy of five figures.
a. General. The plug-in assembly re-
pair procedures direct the isolation and
Caution: Always remove the test
repair of trouble in these assemblies.
signal from the test probe before
Tests and alignment are included in the
removing power from the TS-1777/
procedures. A separate procedure is pro-
VRM-1.
vided for each plug-in assembly. Each
procedure consists of preparation, tests,
and isolation steps. The preparation steps
detail the connection of test equipment and
special test cables. The tests indicate the
nature of the trouble. In the isolation
steps, the faulty part is identified. The
tests preceding isolation depend on plug-
in assembly terminal voltage measure-
ments to disclose the nature of the trouble.
Voltage measurements are taken at cir-
cuit points between the plug-in assembly
terminals to isolate the faully part.
b. Preparation.
(1) A TS-1777/VRM-l known to be
good is used as a test fixture. The
plug-in assembly to be tested is
connected, through cable No. 11
C. Tests.
assembly in the TS-1777/VRM-1.
(1) Tests are performed following the
The test equipment is connected to
preparation to disclose the nature
t h e connectors or other points
of the trouble. The tests compare
specified to establish the proper
present performance of the circuit
connections for tests and faulty
functions with original acceptance
parts isolation. In general, addi-
levels including the alignment of
tional connections or changes to
individual components.
connections will riot be required.
(2) The tests will disclose the loss of
The plug-in assembly to be tested
any of the plug-in assembly circuit
is provided with the proper ter-
functions. If loss of function or
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