White Outdoor 700 Series, Руководство по обслуживанию

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700 SERIES LAWN TRACTORS
42
17.35. Ground issues : It is relatively easy to track
where power is on the positive side of the sys-
tem. The negative side is frequently neglected,
though it may account for just as many electrical
problems as the positive side.
17.36.Most technicians’ first instinct when testing
ground paths is to set the multimeter to the
Ohms scale (
Ω)
and look for continuity using
resistance as a measurement. This method
does give a rough idea if the circuit is complete
or not.
17.37.Resistance is not the most definitive scale for
identifying circuits that are complete, but have
reduced current carrying capacity because of
bad connections, physical damage, or corrosion.
17.38.As a point of illustration, a short length of 12 or
14 gauge stranded wire can be stripped at the
ends to facilitate an Ohm read-
ing. See Figure 17.38.
17.39.For comparison, strip away insulation at the mid-
dle of the wire, and snip strands until only a few
remain. Repeat the Ohm reading. There will
not be a substantial change. See Figure 17.39.
• While the actual resistance did not change, the
ability of the whittled-down length of wire to carry
current is vastly reduced.
• Similar effects occur when a terminal is not firmly
crimped, a connection is loose, insulated by
paint or corrosion, or the wire is chafed, cut, or
corroded.
17.40.A more effective way to identify this reduced cur-
rent carrying capacity is to look for “voltage
drop”.
Figure 17.38
Undamaged
wire
Figure 17.39
Stripped and
partially severed
wire