Ericsson MGM 450, Maintenance Manual

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PREVENTIVE MAINTENANCE
To ensure high operating efficiency and to prevent mechanical and electrical failures from interrupting system
operations, routing checks should be made of all mechanical and electrical parts at regular intervals. Preventive
maintenance should include the following checks:
CONNECTIONS
Ground connections to the voltage source should be periodically checked for tightness. Loose or poor connections to
the power source will cause excessive voltage drops and faulty operation. When ground connections are not made
directly to the batter, the connection from the battery to vehicle chassis must be checked for low impedance. A high
impedance may cause excessive voltage drops and alternator noise problems.
ELECTRICAL SYSTEM
Check the voltage regulator and alternator or generator periodically to keep the electrical system within safe and
economical operation limits. Over voltage is indicated when the battery loses water rapidly. Usage of 1 or 2 ounces
of water per cell per week is acceptable for batteries in continuous operation. A weak battery will often cause
excessive noise or faulty operation.
MECHANICAL INSPECTION
Since mobile units are subject to constant shock and vibration, check for loose plugs, nuts, screws and other parts to
make sure that nothing is working loose.
ANTENNA
The antenna, antenna base and all contacts should be kept clean and free from corrosion. If the antenna or its base
should become coated or poorly grounded, loss of radiation and a weak signal will result.
ALIGNMENT
The transmitter and receiver meter readings should be checked periodically, and the alignment "touched up" when
necessary. Refer to the Alignment Procedure in this Service Manual.
FREQUENCY CHECK
Check the transmitter frequency and deviation. Normally, these checks are made when the unit is first put into
operation, after the first six months, and once a year thereafter.
MONOGRAM SERIES LBI-38865
PREVENTIVE MAINTENANCE
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Nov. 94