Figure 7-15. - Single-pole oven timer wiring schematic.
Identifying and locating problems within circuits, appliances, and equipment is a challenging job. This phase of your rating as a Construction Electrician (CE) working within a maintenance shop is where much of your career will be spent.
To locate faulty conditions in circuits, you need to perform some inspecting, some calculating, and some instrument testing. A few moments spent studying the schematic or drawing of a particular circuit before the actual troubleshooting begins often simplifies the task of isolating the trouble. THINK! If a circuit fails to operate properly, apply some logical reasoning when you check for the fault. The trial-and-error method is inefficient and time-consuming.
When you troubleshoot a circuit, the first thing you want to do is study the schematic; the next step is to inspect the circuit visually. Check for loose connections, loose wires, burnt wires, and burnt components, and check the type of wiring.
Careful inspection of electrical components and equipment is essential to preventing fire hazards caused by defects or dangerous conditions. These inspections include checking for cleanliness, normal operation, operation under load, tight connections, adjustment, and lubrication Always perform a visual inspection first. In this inspection, examine the general condition of the equipment, determine whether it was abused, dropped, or overloaded or is inoperative because of continued use. The general condition of a unit can help you to determine the fault within it.
Testing and maintaining equipment is best accomplished at the time of inspection. Completing everything without returning to the area saves time. Tools and test equipment should be taken to the job site when the inspection is performed.
One of the primary responsibilities of a CE is to ensure proper operation of switches and elements used in appliances and equipment. That can be done by developing and following a good inspection and maintenance program. Periodically, you should check all equipment for loose connections, burned or pitted contacts, and the improper mounting of switches. You should also check for bad connections, improper mounting, and loose or broken insulators on coils or ribbon elements.
The inspection and maintenance of switches and elements on appliances and equipment go hand in hand, and, in most cases, a problem discovered during inspection is corrected on the spot and requires no further work until the next inspection.
A bad appliance should first be checked visually. If you fail to find the trouble by visual inspection, you will find that a meter is an indispensable device in testing electrical circuits of appliances.
Power Supply and Cord
When you attempt to repair an inoperative appliance, do not be in a hurry to disassemble it to find the trouble. You should first pull the power cord from the outlet and determine if there is current at the outlet. If the outlet is energized, inspect the power cord. Next, examine the plug connections for cleanliness and tightness. Finally, inspect the power cord for any broken wires. If the condition of the cord makes it unserviceable, replace it before going any further in your troubleshooting procedure.
Checking the power supply and the condition of the power cord should be the first thing you do when you attempt to find an electrical fault in an appliance. In a number of cases, electrical faults are found in the powercord, rather than in the appliance itself. Only when youhave determined that the fault is not with the powersupply or cord, should you consider troubleshooting theinternal units. To troubleshoot these units effectively, you have to disassemble part of the appliance.Continue Reading