37. NO LOUD RUSHING NOISE AT THE COMMANDER'S C-2298 (EPC STEP 36).
a. Situation 23.
This indicates the B-receiver unmuted monitoring
circuit (monitor switch at B) is bad.
This symptom is caused by an open
Trace the B-receiver unmuted monitoring (phone out) circuit on
your system diagram and identify the following possible bad items of
equipment: R-442, MT-1898, J-3514, CX-7058/VRC, and AM-1780.
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
disturbance, followed by continuity measurement.
c. Test procedure 78. The first test is at the AM-1780.
CX-7058/VRC from the AM-1780 J510.
With the multimeter, circuit disturb J510 pin H to pin A.
If no disturbance is heard (handset connected to CDR RAD Jack
J802), the AM-1780 is bad.
If disturbance is heard, set the R-442 to OFF.
Remove the R-442 from the MT-1898 and measure continuity from J14
pin H to the CX-7058/VRC pin H.
If zero ohms is measured, the R-442 is bad.
If infinity is measured, disassemble the MT-1898 mount.
Remove the CX-7058/VRC from the J-3514/U J1.
Measure continuity on the CX-7058/VRC, end-to-end, pin H.
If infinity is measured, the CX-7058/VRC is bad.
If zero ohms is measured, remove the J-3514/U P1 from the MT-1898
Measure continuity on the MT-1898 J14 pin H to J12 pin H.
If infinity is measured, the MT-1898 mount is bad.
If zero ohms is measured, the J-3514/U is bad.
38. THE TSEC/KY-57 INPUT POWER APPLIED, OTHER ACTIONS OCCUR (EPC STEP 40a).
a. Situation 24. Input power is applied to the KY-57, when the OFF-ON TD
switch is turned to ON.
Also, the KY-57 (initial turn on) activates the
internal ALARM circuit, applying ALARM tone beeps through the system to the
earphone of the handset. Also, a ground is applied to the squelch disable
circuit (through KY-57 to the RT), disabling the RT squelch circuit and
turning the call light on. Two symptoms may occur: