Components And Testing Techniques - Cub Cadet CC 500 EL Shop Manual

ELECTRICAL SYSEM

Components and testing techniques

In this section, the function and test procedures of indi-
vidual components will be looked at.
Switches
In order to bench test a switch, the way it operates
must be known. All switches either open a circuit or
close a circuit. The difference between switches is their
resting state and how many circuits they control. When
the switch controls more than one circuit, it could have
one side normally open and the other normally closed.
It could also have all sides the same.
Normally closed switches (NC)
A switch that while resting (off) closes (has continuity or
allows current to flow through it) a circuit is called a nor-
mally closed switch. when the switch is activated it will
open the circuit.
Normally open switches (NO)
A switch that is open (does not have continuity) when
in a resting state is called a normally open switch.
When activated the switch will close the circuit. The
tabs for a normally open switch generally are
unmarked.
The switch used in this mower is known as a double
pole double throw switch. Double pole basically means
that it has two separate switches inside one housing
that act as one. Double throw means that each switch
has a normally open contact and a normally closed
contact. See Figure 2.10.
DPDT switch
Figure 2.10
Schematic drawing
Testing a switch
When testing a double pole double throw switch, treat it
as two switches. Test one side of the switch in the open
and closed state then do the same on the other side. To
test a switch:
NOTE: There is usually a schematic drawing on
the side of the switch that will show which tabs
are in what circuit. See Figure 2.10.
1. Uplug the power cord.
2. Remove and open the switch box assembly by
following the steps described in chapter 3 Repair
Procedures.
3. Remove the switch from the circuit.
4. Set the DVOM to the ohms scale (
5. With the switch in the off position touch one
probe to the one of common tabs and the other
probe to the NC tab for that circuit.
NOTE: The DVOM should read zero resistance.
6. Move the probe from the NC tab to the NO tab.
NOTE: The meter should show an open circuit.
7. With the probes still attached, turn the switch on.
The readings should reverse, NO should have
zero resistance and a NC switch should indicate
an open circuit.
8. Repeat for all the circuits in the switch
9. If the switch fails in any of the tests, replace the
switch.
NOTE: The part number for just the switch is
725-04435.
10. Install the switch box assembly by following the
above steps in reverse order.
11. Test run the mower before returning to service.
8
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