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14.1 ELECTRICAL SYSTEM REPAIRS
Gravely recommends that all work be done in a
professional manner. Using tubing to cover joints and
soldering connections contribute to a professional
looking job. In addition to a pleasing appearance, repairs
made in this manner are more likely to withstand
vibration. The weakest points in any electrical system are
the joints where wires are attached.
Replace all defective components only with Gravely
replacement parts. Engine parts, such as rectifiers or
alternator components should be acquired through the
nearest engine service center.
Gravely does not recommend attempting to repair
electrical components. Most do not lend themselves to
repair. You would have more money invested in "time to
repair" than the part would cost, plus the results may not
be as good.
14.2 TOOLS
There are some specialized tools and test equipment that
are needed for electrical repair work. A brief description
of these follows.
Long or needle nose pliers - used to connect or bend
wires and connectors in close quarters.
Diagonal cutters - used to cut wires or trim connections.
Wire stripper/crimping tool - available separately or as
a combination tool. Used to strip insulation from wires of
various sizes and to crimp terminals and connector or
wires.
Soldering gun or soldering iron - used to solder all
splices and connections to terminals, connector, etc. A
soldering gun is faster and more convenient that waiting
for a soldering iron to heat.
Multimeter - analog or digital, to measure voltage,
amperage and ohms.
Tachometer - used to measure engine speed. Required
to properly test alternator and charging circuits where
output is dependent upon engine speed.
Heat gun - used to shrink insulated tubing in place. Used
to replace electrical tape or insulated sleeving. To use,
place a piece of shrink tubing over a wire joint, heat with
the heat gun, until it shrinks slightly around the joint.
Supplies - electrical tape, rosin core solder (never use
acid or acid core solder on electrical joints), an
assortment of various size terminals, connectors,
insulated or heat shrink tubing (for use on joints and
connections), and an assortment of automotive type wire
(in several colors).
SECTION 14 - ELECTRICAL SYSTEM
14.3 ELECTRICAL MEASUREMENTS
In many electrical circuits, some visible effect indicates
that the circuit is functioning properly. A switch is turned
"ON" and a lamp lights. A key is turned, a starter motor
runs and cranks the engine.
If the lamp does not light, or the starter motor does not
run, some means of measuring voltage, current flow,
resistance and continuity is needed, (continuity means
there is a complete electrical path through the circuit or
component.)
To know exactly what conditions exist in an electrical
circuit requires AC and DC voltmeter, AC and DC
ammeter, and an ohmmeter.
Multimeter
A single combination meter that does all of these things
is available. Such a meter is called a multimeter or volt-
ohm-multitester (VOM). Meters of this kind are available
in many forms and all change functions and ranges with
switches, or by plugging test leads into different jacks.
Multimeters are available in two basic types, analog and
digital. Either type of meter may be used for the
measurements that follow. Test procedures are the same.
It is best to learn proper procedures, even though some
meters may be more forgiving of mistakes. Where
differences in use may occur, they will be covered in the
discussion.
Analog Meters – Analog meters have a needle that
moves across a scale to give a reading. The longer the
scale, the easier it is to read and more accurate the
reading will be. A jeweled movement used in this type of
meter is more likely to be damaged through rough
handling (except overloaded protected meters) or by
measuring high values that exceed the range set on the
meter than a digital meter. They provide excellent service
for the money as long as they are used with care.
Digital Meters – Because digital meters do not have a
movement, they are more rugged. The reading shows up
directly on a display window. Since they read directly, no
skill in reading the scale is required, nor is it necessary to
set the range. The meter switches the ranges
automatically. One has only to select the function DC
volts, AC ampere, ohms, etc.), connect the test leads,
and the reading is shown on the display. Because of the
internal circuitry and the lack of a movement, these
meters are not likely to be damaged by overloads.
Voltage Measurement
Remember two basic rules when using a voltmeter: (1) a
voltmeter measures the voltage difference between the
test leads, and (2) a voltmeter is always connected
across the circuit under test.
14 - 54
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