35. NO LOUD RUSHING NOISE HEARD AT THE COMMANDER'S C-2298 (EPC STEP 33).
a. Situation 21. This indicates the A-RT unmuted monitoring (monitor
switch at A) circuit is bad.
This symptom is caused by an open circuit.
Trace the A-RT unmuted monitoring circuit and identify the following
possible bad items of equipment: AM-1780 CX-4723 J-3513/U (Figure 99. Issued
as adjunctive material.).
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 technique for this type defect is continuity
measurement.
c. Test procedure 76.
The first test is to check the AM-1780.
Turn
the RT and AM-1780 to OFF.
Remove the two CX-4723s from J504 and J501.
Measure continuity at J504 pin M to J501 pin H.
If infinity is measured, the AM-1780 is bad.
If zero is measured, remove the RT from the MT-1029.
Disassembly the MT-1029.
Remove the CX-4723 from the J-3513/U J7.
Measure continuity on the CX-4723, end-to-end, pin H.
If infinity is measured, the CX-4723 is bad.
If zero ohms is measured, the J-3513/U is bad.
36. NO LOUD RUSHING NOISE AT THE COMMANDER'S C-2298 (EPC STEP 35).
a. Situation 22.
This indicates the B-receiver muted monitoring
circuit (monitor switch at ALL) is bad. This symptom is caused by an open
or short circuit.
Trace the B-receiver muted monitoring (monitor 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 77.
The first test is at the AM-1780.
Remove the CX-7058/VRC from the AM-1780 J510.
With the multimeter, circuit disturb pin K to pin A J510.
If no disturbance is heard (handset connected to CDR RAD Jack
J802), the AM-1780 is bad.
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