3. Read and translate the text.

There is a definite philosophy behind troubleshooting that should be understood and followed if it is to be effective. Troubleshooting is a logical process of evaluating a system and how it operates. It involves collecting evidence such as burn marks or heat, unusual sounds, acrid smells, temperature variations, etc. All the senses can be used to compile a problem profile. This can be supported by using instruments correctly and by analyzing the data displayed on them. This information forms the basis for testing theories and assumptions, so that the precise fault can be identified and rectified. The following factors must be considered in any troubleshooting exercise.

a. Systems Knowledge. Understand the basic operations of the equipment, it is common to find that "faults" are in fact only improperly operated equip­ment. If there is a basic understanding of the system, it is considerably eas­ier to break it down into functional blocks, which makes trouble­shooting much easier.

b. Systems Configuration. Understand where all system components are installed, where connections and cables are, and where supply voltages orig­inate from.

c. Systems Operation Parameters. Understand what is "normal" during op­eration, and what are the parameters or operating rangers of the system. More often, expectations are different from the realities.

d. Test Equipment. Understand how to use a basic multimeter, be able to make simple tests of voltage and continuity of conductors.

Troubleshooting Procedure.

The following approach should be used:

a. System Inputs. Check that the system has the correct power input. Don't assume anything. For example, there may be a voltage input, but it may be too low. Check it with a multimeter.

b. System Outputs. Does the system have an output? Is the required voltage or signal being put out? If there is input and no output, then you have al­ready isolated the main problem.

c. Fault Isolation. In any troubleshooting exercise, split the system in two. This method is ideal when troubleshooting lighting circuits, it instantly iso­lates the problem into a smaller, more specific area.

d. Fault Complexity. Most problems usually turn out to be rather simple. Start with the basics, and don't try to apply complex theoretical ideas which you do not fully understand. Stand back and think first.

e. Failure Causes. When a fault has been isolated and repaired, try to ascertain why the failure has occurred.

Instrument Use.

Effective troubleshooting of electrical devices requires the proper use of the multimeter.

a. Continuity Tests. The continuity test, which requires the use of the ohm setting, simply tests whether a circuit is open or closed. Power must be switched off before testing. Set the scale to one of the megOhm rangers. Place the probes on each wire of the circuit being tested. What you are looking for is a simple over-range reading if the circuit is open, and low or no resistance if closed. Many multimeters also incorporate a beeper to indicate a short circuit.

b. Resistance Tests. Set the range switch to the circuit being tested. Typically, a 20-ohm range is used. Turn off circuit power and discharge any capacitors. When testing, do not touch probes with your fingers as this may alter readings. Before testing, touch the probes together to see that the meter reads 0.

c. Voltage Tests. The most practical of all measurements is voltage, either to detect that it is present or to precisely measure its exact level, as is done when testing charging systems and batteries. 99% of all troubleshooting on complex oil rigs and commercial vessels are done with this function alone. The voltmeter is connected across a load with negative probe to negative and positive to positive (it is measuring the voltage potential between the two). Reversing the probes will show a negative reading. Set the scale to the one that exceeds the expected or operating voltage of the circuit under test.

d. Current Tests. The ammeter function on the multimeter is rarely used or required, although some use it for locating leakages. The ammeter on the switchboard can normally be used for all measurements. An ammeter is always connected in series with a circuit since it is measuring the current passing through the wire. The circuit should be switched off before inserting the ammeter in circuit.

Meter Maintenance. Look after your meter. Do not drop it or let it get wet.

A few basics will ensure reliability and safety:

(1) Probes. Keep the probes in good condition. On many probes, the tips sometimes rotate out and short circuit the terminals being tested. Another problem is that the solder connections of test leads can break away due to twisting and movement.

(2) Cables. Keep the cables clean and the insulation undamaged. Cables do age and crack. Do not attempt to test higher voltages, in particular AC volt­ages, with damaged cables. If a cable is damaged, replace it.

(3) Batteries. Replace the internal battery every 12 months, or carry a spare. Many meters will have a low battery warning function.