Service manual

STP 11-25R13-SM-TG
T - 25
Section VI. OTHER PRECAUTIONS
T-33. Troubleshooting, Repairing, and Calibrating Equipment.
a. Inspect all interlock safety switches and fuses to insure that they are in good condition. Safety
devices, such as interlocks, fuses, circuit breakers, and limit switches, will not be bypassed unless
removal is essential for performance as provided in pertinent manuals or SOP. Power will not be applied
to a circuit in which the safety devices have been eliminated, unless elimination of such safety devices is
essential for the proper performance of calibration or maintenance. Be extremely careful when working
on circuits where safety devices or interlocks have been bypassed.
b. Should a power failure occur during the operation of electrical test equipment, the breakers
(powering the equipment) and the test equipment will be turned off.
c. Cables will always be connected or disconnected by grasping end connectors, and not by
pulling the cable leads.
d. In troubleshooting or calibrating electrical/electronic equipment, the technician will not place one
hand on an energized component and the other on an electrical ground, such as the chassis of the
equipment. A suggested method of working on such equipment is to use only one hand for probing while
keeping the other hand in the pocket or behind the back. When performing operations requiring the use
of both hands, (e.g., when making voltage measurements with a voltmeter), both insulated leads should
be firmly held and placed firmly on test points. Where high voltage is present, deenergize equipment and
connect all required leads to test points with wooden stick or insulated clips; then, reenergize to make the
measurement.
e. The following additional precautions are to be observed when troubleshooting, repairing, or
calibrating electrical/electronic equipment with exposed circuitry.
(1) Make sure that high voltage capacitors on deenergized equipment are discharged before
working on or near them if the cover has been removed, or if the voltage can be reached from the outside
of the chassis.
(2) Remove personal bracelets, watches, rings, or other metal objects from hands and arms.
(3) Make sure that rescue equipment, such as ropes and hot sticks, is available in the immediate
area.
(4) Two persons must be in the immediate work area at all times while work is being performed on
exposed circuits carrying over 30 volts rms or dc to assure that one person is available to render
assistance in case of accident.
(5) General Purpose First Aid Kit, NSN 6545-00-922-1200, will be provided and maintained in all
mobile facilities that operate over the highways, or in shelters not in close proximity to a medical facility.
f. Do not handle energized electrical equipment when hands, feet, or body are wet or perspiring,
or when standing on a wet floor.
g. When it is necessary to touch electrical equipment (for example, when checking for overheated
motors), use the back of the hand; therefore, if accidental shock were to cause muscular contraction, your
hand would pull away rather than uncontrollably grab the equipment.
h. The possibility of high frequency burns is not confined to RF equipment, but can exist in large
audio-frequency equipment due to high frequency parasitic oscillation.