The Isolation Method of Troubleshooting

Electrical technicians who have to troubleshoot large or multifaceted systems are only able to do their jobs effectively if they can quickly isolate a problem to a single subsystem. You may have heard the story of the mechanic who was called to fix a car that wouldn’t start. He turned one single screw and the car started right up. He handed the customer a bill for $100.10. The customer wanted to know why the bill was so high, when the mechanic hadn’t done anything other than turning a single screw. The mechanic replied that $0.10 was the charge for turning the screw, and $100 was for knowing which screw to turn.

Technicians who know how to fix systems effectively do so by the process of elimination. Let’s say, for example, that you have a group of electrical cabinets connected together by computer network communication cables. Suppose there are 100 of these cabinets, and somewhere along the line, there is a break in the signal. You might go to the 50^th cabinet and see if the signal has made it that far. If it has, then you have eliminated the first 50 cabinets and cut the problem in half. If the signal has not made it that far, then you know that the problem exists in the first 50 cabinets and not the last half. You can then go to the 25^th or 75^th cabinet, as appropriate, and repeat the process all over again.

Eliminating Suspects

Unfortunately, the example above is not a typical example of a fault. In reality, it’s much more complex than that. In electromechanical systems, such as copying machines or car washes, there are moving parts and electrical control systems that work together in tandem. It’s not always easy to isolate the fault to a single place. This is where the art of troubleshooting comes in. It’s all about creating conditions that reveal the true nature of a problem.

In a copying machine, for example, you might have a situation where the copies all come out blank. In older analog copying machines—unlike today’s copying machines, which are basically scanners attached to laser printers—there was a set of mirrors that directed a beam of light onto a photographic “drum” which would attract toner to the exposed areas. A blank copy might mean a broken or misaligned mirror—or it might mean that the “transfer” (an electrical charge designed to pull toner off of the drum) was not working. A technician might start making a copy and open the side of the machine partway. If there is toner on the drum in the shape of the image, that would eliminate the mirror optics as a suspect.

The more different subsystems there are, the more difficult it can be to trace and identify the nature of a problem. However, if you get in the habit of asking yourself the question, “How can I eliminate a subsystem as a suspect,” you will find the problem of electrical troubleshooting becoming both simpler and easier.

Tags: electrical, mechanic, technician, trouble shooting

This entry was posted on September 3rd, 2013 and is filed under Electrical, Technology. Both comments and pings are currently closed.