Specifications

CHAPTER 3
FIFTH ECHELON MAINTENANCE
Section I. TROUBLESHOOTING AND REPAIR
53. General
This chapter includes troubleshooting
and repair procedures to be performed
by fifth echelon maintenance facilities. It
includes detailed isolation, replacement,
and adjustment data for the plug-in as-
semblies. Chapter 4 includes fifth echelon
final testing procedures.
54. Plug-In Assembly Repair Procedures
a. General. The plug-in assembly re-
pair procedures direct the isolation and
repair of trouble in these assemblies.
Tests and alignment are included in the
procedures. A separate procedure is pro-
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
(fig. 21), in place of the equivalent
assembly in the TS-1777/VRM-1.
The test equipment is connected to
the connectors or other points
specified to establish the proper
connections for tests and faulty
parts isolation. In general, addi-
tional connections or changes to
connections will riot be required.
The plug-in assembly to be tested
is provided with the proper ter-
(2)
(3)
minals by other plug-in as-
semblies.
In addition to the listed test equip-
ment, cables No. 10 and 11 (fig.
21) are required.
When the frequency of a signal
generator is specified without an
accompanying tolerance, set the
frequency to the number of signi-
cant figures expressed. For ex-
ample, 11.500 mc is set to an ac-
curacy of five figures.
Caution: Always remove the test
signal from the test probe before
removing power from the TS-1777/
VRM-1.
C. Tests.
(1)
(2)
Tests are performed following the
preparation to disclose the nature
of the trouble. The tests compare
present performance of the circuit
functions with original acceptance
levels including the alignment of
individual components.
The tests will disclose the loss of
any of the plug-in assembly circuit
functions. If loss of function or
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