17. TSEC/KY-57 NO INPUT POWER.
a. Situation 9.
When performing TSEC/KY-57 input power EPC step 42,
the KY-57 power switch is turned to ON. The R-442 call lamp does not light
and alarm beeps are not heard in the speaker.
This symptom indicates no
power to the KY-57. To confirm power, measure voltage of 5.2 volts DC on
the KY-57 (turned on) audio connector pin A to pin C.
If no voltage is
measured, this indicates the KY-57 input power circuit is bad. Tracing the
KY-57 input power circuit identifies the following possible bad items of
equipment (Figure 55).
Figure 55.
KY-57 input power circuit, R-442 (possible bad items).
b. General test procedures. You must determine the type of tests and
the location of the test points to identify the actual bad item of
equipment. Troubleshooting techniques for this type of defect are voltage
measurements, followed by continuity measurements (Figure 56).
c. Test procedure 34. The first voltage test point (TP1 of Figure 56)
is between pins N(+) and G(-) on plug P2 of the CX-13061/U. Pins N and G,
through the CX-13061/U and the KY-57, provide a ground for the J-3514 K1.
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