24. A-RT MODULATION, PLAIN TEXT, KY-57 TURNED OFF.
a. Situation 13.
When performing EPC step 21, NO VOICE SIDETONE is
observed. This indicates the A-RT modulation circuit is bad. This symptom
is caused by an open or a short.
Trace the A-RT MODULATION circuit and
identify the possible bad items of equipment (Figure 87).
Figure 87.
MODULATION circuit, no voice sidetone (possible bad items).
b. General test procedures.
You must determine the type of test and
the location of the test points to identify the actual bad item of
equipment. Troubleshooting techniques for this type of defect are circuit
substitution, followed by continuity measurements.
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