IFR FM/AM-500, Maintenance Manual

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SECTION 7 - MODULE TESTING
7-1 GENERAL
This section contains detailed testing procedures for the modules and
PC Boards which make up the FM/AM-500A. These procedures are intended
to aid the technician in determining whether the module, identified
during troubleshooting procedures, is actually faulty. Failure to
obtain a specified test result normally indicates one or more of the
components in that portion of the circuit may be defective. However,
do not rule out the possibility that another circuit or module may
cause the improper test result.
Each test procedure in this section provides the following information
for the module under test:
1. Theory ot module operation with functional block diagram;
2. Preparations required to commence test procedures;
3. Step-by-step test procedures.
During testing, refer to Section 6 for mechanical assembly drawings.
PC Board layout drawings are in Section 9, and circuit schematics are
in Section 10.
After repairing or replacing a module, it is essential to conduct
appropriate Calibration Procedures before returning the FM/AM-500A to
service.
7-1-1 MODULES RECOMMENDED FOR FACTORY REPAIR
The Dual VCO Module and the 88-90 MHz bandpass filter poles in the IF
Module are not field repairable and should, therefore, be returned to
the IFR Factory for repair.
7-1-2 DISASSEMBLY REQUIREMENTS
Removal of the exterior case from the FM/AM-500A is a primary require­
ment for performing the test procedures in this section. In addition,
most of the procedures also require that the module under test be
removed from the set to allow access to test points, internal compon­
ents, etc. The technician should refer to "SECTION 6 - DISASSEMBLY/
REASSEMBLY PROCEDURES" for instruction for removing and disassembling
individual modules.
7-1-3 TEST EQUIPMENT REQUIREMENTS
Appendix B at the back of this manual contains a comprehensive list of
test equipment suitable for performing any of the procedures in this
manual. Any other equipment meeting the specifications listed in the
appendix or specific test procedure may be substituted in place of the
recommended models.
7-1