Troubleshooting the Shorting Faults in Parallel Circuit
As in a series circuit, a short in a parallel circuit will usually cause an open circuit by blowing the fuse. But, unlike a series circuit, one shorted component in a parallel circuit will stop current flow by causing the fuse to open. Refer to the circuit in Figure 10-177.
If resistor R3 is shorted, a path of almost zero resistance will be offered the current, and all the circuit current will flow through the branch containing the shorted resistor. Since this is practically the same as connecting a wire between the terminals of the battery, the current will rise to an excessive value, and the fuse will open. Since the fuse opens almost as soon as a resistor shorts out, there is no time to perform a current or voltage check. Thus, troubleshooting a parallel DC circuit for a shorted component should be accomplished with an ohmmeter. But, as in the case of checking for an open resistor in a parallel circuit, a shorted resistor can be detected with an ohmmeter only if one end of the shorted resistor is disconnected and isolated from the rest of the circuit.
Troubleshooting the Shorting Faults in Series-Parallel Circuit
Logic in Tracing an Open
Troubleshooting a series-parallel resistive circuit involves locating malfunctions similar to those found in a series or a parallel circuit. Figures 10-178 through 10-180 illustrate three points of failure in a series-parallel circuit and their generalized effects.
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