TM 11-6625-2980-14
TM 503 SYSTEM MAINTENANCE
Section III. GENERAL
Introduction
This section of the manual is meant to support the
entire TM 500 Series family of modules with a general
coverage of the most commonly-needed service
information pertinent to preventive maintenance,
troubleshooting, ordering parts, and replacing
components and sub-assemblies.
Cabinet Removal
Dangerous potentials exist at several points
throughout the system. When the system must
be operated with the cabinet removed, do not
touch exposed connections or components.
Some transistors have voltages present on
their cases. Disconnect power before cleaning
the system or replacing parts.
Two screws on the top secure the cabinet to the TM
503 frame. Remove them and lift the cabinet straight
up. Do not operate the system with the cabinet
removed any longer than necessary for troubleshooting
and calibration. Re-install the cabinet to protect the
interior from dust and to remove personnel shock
hazards.
Cleaning
Adequate ventilation should be provided while
using TRICHL ORO TRIFL UO ROE THA NE.
Prolonged breathing of vapor should be
avoided. The solvent should not be used near
heat or open flames; the products of
decomposition are toxic and irritating. Since
TRICHLORO TRIFLUOROETHANE dissolves
natural oils, prolonged contact with skin should
be avoided. When necessary, use gloves
which the solvent cannot penetrate. If the
solvent is taken internally, consult a physician
immediately.
Exterior. Loose dust may be removed with a soft
cloth or a dry brush. Water and a mild detergent may be
used; however, abrasive cleaners should not be used.
Compressed air is dangerous and can cause
serious bodily harm if protective means or
methods are not observed to prevent a chip or
particle (of whatever size) from being blown
into the eyes or unbroken skin of the operator
or other personnel. Compressed air shall not
be used for cleaning purposes except where
reduced to less than 30 p.s.i.f. and then only
with effective chip guarding and personnel
protective equipment. Do not use compressed
air to dry parts when trichlorotrifluoroethane
has been used.
Interior. Cleaning the interior of a unit should
precede calibration since the cleaning processes could
alter the settings of calibration adjustments. Use low-
velocity compressed air to blow off accumulated dust.
Hardened dirt can be removed with a soft, dry brush,
cotton-tipped swab, or a cloth dampened in a solution of
water and mild detergent.
Preventive Maintenance
Preventive maintenance steps performed on a
regular basis will enhance the reliability of the
instrumentation system. However, periodic checks of the
semiconductors in the absence of a malfunction are not
recommended as preventive maintenance measures.
See the semiconductor checking information under
Troubleshooting Techniques which follow. A convenient
time to perform preventive maintenance is just before
instrument calibration.
Calibration
To insure accurate signal generation and
measurement, the performance of individual units
comprising the system should be checked periodically.
Refer to TB 11-6625-2980-35 for complete calibration
procedures.
A-7
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