Preventive Maintenance

Conduct a test announcement from station 1 over

3. Turn the METER TEST switch to position 3 to

circuit 6MC. The circuit 6MC busy signal light should

test the power amplifier A output as the various

illuminate at all stations, and the announcement should

alarm test switches are energized.

be heard over the 6MC loudspeaker(s) only.

4. Hold the CHEMICAL test switch in the ON

position. The meter reading should be 02 dB.

ALARM CONTACT MAKER TEST.-- When

Release the switch.

conducting a test of the alarm contact makers, you must

monitor all the microphone stations and at least one

5. Hold the COLLISION test switch in the ON

loudspeaker in each loudspeaker group and any visual

position. The meter reading should fluctuate.

alarm indicators. Test the alarm contact makers in order,

Release the switch.

beginning with the lowest priority alarm first. The

6. Operate the GENERAL test switch momentarily

following procedure is for testing the general, chemical,

in the ON position. The meter reading should

and collision alarm contact makers only:

fluctuate for approximately 15 seconds. Release

1. Operate the general alarm contact maker

the switch.

momentarily to the ON position. The alarm should

7. Hold the UNASSIGNED test switch in the ON

sound for approximately 15 seconds.

position. The meter reading should fluctuate.

2. While the general alarm is sounding, operate the

Release the switch,

chemical alarm contact maker to the ON position and

8. Hold the FLIGHT CRASH test switch in the ON

hold it there. The chemical alarm should override the

position. The meter reading should fluctuate.

general alarm.

Release the switch.

3. While the chemical alarm is sounding, operate

This completes the testing of channel A and

the collision alarm contact maker to the ON position.

oscillator group 1. To test charnel B and oscillator group

The collision alarm should override the chemical alarm.

2, turn the AMPLIFIER CHANNEL SELECTOR

4. Return the chemical and collision alarm contact

switch to the 1MC-A/6MC-A position and the

makers to the OFF position.

OSCILLATOR GROUP SELECTOR switch to the NO.

1 position. Turn the METER TEST switch to position 4,

Operation of any alarm should light up the busy

and repeat steps 4 through 8.

signal lights and all visual alarm indicators of circuit

1MC and circuit 6MC. As each alarm contact maker is

Remote Testing

operated, the corresponding alarm should be heard over

all the circuit 1MC loudspeaker groups.

Remote testing consists of a test of the entire system.

The test will include testing for proper operation of the

MAINTENANCE

system from the microphone control stations and the

alarm contact makers. Figure 7-24 illustrates the proper

Maintenance of the system consists of routine

switch positions on the control rack for remote testing.

preventive maintenance and corrective maintenance.

MICROPHONE CONTROL STATION

Preventive Maintenance

TEST.-- When conducting a test of a microphone

control station, you must monitor all the other

Routine preventive maintenance of the system will

microphone stations and at least one loudspeaker in each

be accomplished according to the maintenance

loudspeaker group. Make several test announcements

requirement cards (MRCs) for the system, In most

over circuit 1 MC, selecting a different loudspeaker

cases, this will consist of cleaning the interior and

group for each transmission. The volume indicators

exterior of each rack, a visual inspection of equipment

should fluctuate at all stations, and the circuit 1 MC busy

components and wiring, checking for loose connections,

signal light should illuminate when each test

and testing the power amplifier tubes.

announcement is made. Each test should be heard on the

loudspeaker of the loudspeaker group selected and not

Corrective Maintenance

on loudspeakers of any other loudspeaker group. Check

the priority feature of microphone station 1 by

depressing the press-to-talk switch at station 1 while

Corrective maintenance of the system consists of

making an announcement from another station. This

troubleshooting and actual replacement of defective

parts. When performing corrective maintenance, you

should cut off the other station.

7-20