Troubleshooting

Troubleshooting is the process of solving problems, especially complicated problems in a system, as defined by Cambridge dictionary. Simply it is a method of finding the cause of a problem and correcting it. The ultimate goal of troubleshooting is to get the equipment back into operation. This is a very important job because the entire production operation may depend on the troubleshooter's ability to solve the problem quickly and economically, thus returning the equipment to service. Although the actual steps the troubleshooter uses to achieve the ultimate goal may vary, there are a few general guidelines that should be followed.

The troubleshooting process consisting of several steps followed that are simply combined to be specific to the problem at hand to find the fault and get the system up and running. This article will briefly cover the troubleshooting process.

General Troubleshooting Guidelines

The general guidelines for a good troubleshooter to follow are:

Use a clear and logical approach

• Work quickly
• Work efficiently
• Work economically
• Work safely and exercise safety precautions

Troubleshooting Steps

The troubleshooting process consists of the following:

1. Symptom recognition
2. Symptom elaboration
3. Listing of probable faulty functions
4. Localizing the faulty function
5. Localizing the trouble to a faulty component
6. Failure analysis
7. Retest requirements

When necessary, each of these steps should be used in the proper order. Deciding when each is necessary is a very important part of troubleshooting. This is where a strategy is developed into a procedure. Many of the more modern designs of equipment in use today offer extensive diagnostics programs and tools as an integral part of the equipment. Some have internal troubleshooting programs that allow the equipment to "troubleshoot" itself to a large degree. These programs and tools usually check inputs and outputs against pre-programmed normal parameters. If a discrepancy is noted, that function is flagged as a potential problem. Some programs are more sophisticated and will actually check functions to a component level, but they usually are only found on very expensive and high-tech equipment. The strategy that the program uses is a simple logical input-output comparison. Systems or equipment that are designed for some form of self-troubleshooting obviously do not require implementation of every one of the seven steps. The equipment itself may perform any one or all of the steps, except failure analysis and retest requirements. All that is required of the troubleshooter is an understanding of what the equipment diagnostics are indicating and what the quickest and most effective way of clearing the fault is. When any troubleshooting effort is necessary, writing down or referring to the seven steps will ensure that a conscious decision is made as to what steps apply and what steps do not apply. Approaching the problem in this fashion will ensure that valuable time is not wasted back-tracking to action or thought process that was skipped initially. Next, we will take a look at each of the seven steps individually to see what should be accomplished for each step.

Step 1: Symptom Recognition

This is the most fundamental step in troubleshooting. This step asks the question "Does a failure exist," the first step in identifying a failure is recognizing that a failure exists. This sounds ridiculously simple, and usually, it is, but it is also very important. For example, a common failure can be as simple as the power is not connected to a power supply. Electric motors and electrical circuits will not operate without electricity! This is very simple troubleshooting, but it can save a lot of time and potential embarrassment. The symptom recognition step is very straightforward. It requires an entry in the troubleshooting log that states what the indications of a problem are. For example, the indication might be that pump #3 does not start. Always check for additional symptoms of common problems. Unusual symptoms of common troubles occur more often than common symptoms of unusual troubles. The following list provides some guidelines for entries made during the symptom recognition step:

• Try to be as specific and determining as possible in stating the problem that is occurring.
• Always check to ensure equipment is lined up for normal operation, i.e., On/Off switch, test switch, mode selection switch, etc.
• Analyze the performance of the equipment to make sure it actually has a failure and is not simply reacting to an external condition.
• Try to determine if the failure is total or if the equipment is operating with degraded performance.
• Know the equipment; realize when it is showing the symptoms of impending failure.

Step 2: Symptom Elaboration

The symptom elaboration step is the beginning of "actual" troubleshooting. The objective of this step is to obtain as much information about the problem as possible. Symptom elaboration is where the question "What is the problem" is asked. As its name implies, this step elaborates on the symptom written in step one. For example, perhaps the cylinder extension stroke is too slow, but the retraction stroke timing is satisfactory. This step provides all of the information necessary to narrow the problem down in a logical fashion. The following points would be considered in the symptom elaboration step. * Be aware that a large number of equipment faults can produce similar symptoms. During this step, try to differentiate as much as possible between the characteristics of the symptoms.

• Start the troubleshooting log with as much background information as possible and document each adjustment and its results.
• Note how readings are affected by all modes of operation and switch lineups.
• Be sure to observe all gages, meters, and other indicators as to how they are responding due to the problem.
• Always note if an adjustment does not affect the symptom; this will help eliminate possible causes later on.
• Determine if the trouble has slowly developed (i.e., drift) or if it is a sudden failure.
• Perform control manipulation with care since detrimental effects can occur to associated equipment or components within the failed equipment.

-There may be a possibility of improper pressures, flows, or voltages exceeding maximum design specifications.

• Do not go for the answer in one step. Troubleshooting should be a series of small logical steps, each one chosen to show a result leading to the discovery of the problem or problems. Remember, troubleshooting can last two hours or two weeks. Be sure to record all troubleshooting actions taken in the log accordingly. Do not leave anything to memory.

Step 3: Listing of Probable Faulty Functions

This step is intended to narrow down the possible faulty functions based on the information obtained in steps one and two. A functional block diagram of the equipment and the troubleshooting log (steps one and two) are needed for this step. The question asked by this step is "Would failure of this function cause the symptoms I am seeing." Again, the purpose of this step is to narrow the possibilities down to a list of probable faulty functions. Key points for this step include:

• Always use the functional block diagram to ensure all the possible functions are checked.
• Write down all probable faulty functions, even if it is apparently obvious that some of them are working correctly. Then, write down why it is thought to be functioning correctly.
• Be sure to include functions such as detectors, switches, cables, meters, wiring, connectors, piping, filters, and regulators. Wiring is always a probable cause!
• Do not get locked in on what a technician "knows" the trouble has to be. Past troubleshooting experience and hunches certainly play a part in figuring out which is the faulty function. However, do not ignore hard evidence just because one assumes trouble is known prior to proper troubleshooting steps.
• Always ask: "Would a failure of this function cause these symptoms."

Step 4: Localizing the Faulty Function

This step requires careful evaluation of each of the probable faulty functions listed in the previous step. The goal is to determine exactly which area of the system is causing or generating the problem. This is the first step that requires taking a measurement. The measurement taken may be a system pressure, operating speed, sequence, time delay, temperature, or any variable parameter that is related to the equipment operation. The purpose of this step is not to find the faulty component; it is just to isolate the problem to a circuit or function. More than one of the previously listed probable faulty functions may be contributing to the overall problem. This step is not complete until every listed possibility is properly checked. The following key points should be noted:

• Check all pressures, flows, inputs, and outputs associated with the areas of probable faulty functions.
• If an abnormal reading is obtained, the equipment setup used to obtain the reading and the reading itself should be rechecked.
• Do not be discouraged if several hours of troubleshooting reveal that a function is good. Proving a function is operating properly is important to the troubleshooting effort because it narrows down the possibilities of where the problem is located. The first function you choose to check out often will not be the faulty one.
• Check the troubleshooting log periodically to ensure that troubleshooting efforts are still working in the right direction and have not lost sight of the original troubleshooting goal.

Step 5: Localizing the Fault to a Component

This step continues isolating the fault once the faulty function or functions have been determined. Thorough knowledge of the equipment operation, as well as individual component characteristics, is required for successful completion of this step. Schematic diagrams should be used at this point to ensure that no details go unnoticed. When localizing the trouble to a faulty component, keep in mind the following points:

• Evaluate each component within the faulty function to determine which components are probable sources of the symptoms noted.
• Careful consideration must be given to how each component could affect the overall function of the system under both normal and failure conditions.
• Removal of components from the system and use of a test stand may be helpful or even necessary to ascertain the function of more complex components.

Step 6: Failure Analysis

This step requires the failed component(s) to be repaired or replaced and, most importantly, the cause of the failure corrected. The following key points should be noted.

• Knowledge of component failure modes and rates is very important. Always make a complete check of the associated components of the failed unit.
• A considerable amount of information can be rapidly gained through careful visual inspection.
• Avoid replacing a component until the exact cause of the problem is found and repaired. Keep in mind though; the main purpose of troubleshooting is to get the equipment operational. Additional troubleshooting failure analysis can be done after the equipment is running.
• Documentation is imperative at this point; both to aid in troubleshooting the problem should it return and to point out recurring design deficiencies.

Step 7: Retest Requirements

Now that the equipment is operational check all the functions that have been affected by the failure. Although the equipment has been repaired and is now functioning, all operations must be checked and verified. The information obtained in this step can also aid in troubleshooting next time by providing some baseline information. One key point to remember is:

• Fail Safe: do all checks that will ensure the equipment is operating correctly.