Multi meters are available in many shapes and sizes and many technicians will use several varieties depending on task at hand. Small, hand held "Pen Meters" make working in a junction box a one-handed operation. When selecting a multimeter, consideration should be given to the capabilities needed and the usual working conditions. The price range is as extensive as the list of available features and starts around $10 and goes up to around $3,000.
An appropriate set of test leads is needed to compliment any meter. In most cases, a meter will be supplied with a standard probe set. Many technicians find that special applications require special leads. These include probes that will pierce insulation, have special grabbers to cling to circuit cards, or even a standard alligator clip. Various accessories are also available for a basic meter such as temperature conversion modules and current sensing clamps. These devices can turn a basic DVM in to a world class-troubleshooting tool without a prohibitive cost.
Clamp Meters are valuable devices and are becoming more commonplace. There are units for both AC and DC electrical circuits. An AC clamp works on a transformer principle and when it is brought in close proximity of a wire carrying AC current, the meter can provide the user with an accurate indication of amperage. This is accomplished without disconnecting any wires. A DC Amp clamp is also available and works on a Hall Effect — that is, it senses the electromagnetic field surrounding a conductor. These are very useful tools as current flow in a circuit is a sure means to determine the health of the system in question. The prices on these components range from $70 to $500.
Another device that has been popular with telephone repairmen is a tone generator and inductive probe. By connecting the tone generator to a wire and aircraft ground or wire pair, a signal can be introduced. Then, by placing the inductive probe within about 12 inches of the routed wire (even in a bundle), an accurate determination can be made as to location of a short or open circuit.
What a concept — knowing where the wire fault is before removing all of the aircraft interior and all for a price of $50 to $300.
With all the talk of high tech, high dollar troubleshooting equipment, one of the best diagnostic tools for electrical systems is a magnetic compass or a magnetic stud finder. Most relays, contactors, and motorized electrical devices produce magnetic fields, so by placing a compass or stud finder by an inductive component and energizing it, there will be no doubt if there is current flow. All this capability for $1 to $2.
It is important to note that any equipment used for return to service must be calibrated. That means a calibration sticker must be readily available and should reflect that the device is capable of doing its intended job. Not only is this true for electrical testers, but also for ratcheting crimping tools.
With thoughtful application and proper maintenance, test equipment gives limitless capability for troubleshooting and returning aircraft to service in a timely fashion.
Multimeters, What a concept! Proper selection, use, and care of electrical testers is important By Jim Sparks November 2000 Like most involved in the aircraft maintenance field...
Multimeters and All That Magic Stuff By Michael D. Faircloth February 1998 Working with electrical circuits on aircraft can be unbelievably simple or (hair pulling) complex. How many...
What are the best troubleshooting tools?