basic troubleshooting pwr pt

BASIC TROUBLESHOOTING

STRATEGYDeveloping a

Functional Search Strategy for anEffective Basic

Troubleshooting Process

Developed and presented by Bob Lonzo



COURSE OVERVIEW• Course Objectives

• What is troubleshooting?

• Troubleshooter Styles

• Basic Troubleshooting Search Strategy

• Using the Troubleshooting Tools

• Review and Evaluation


COURSE OBJECTIVESThis course is designed to present to the participant a Basic Troubleshooting Search Strategy that can be used to troubleshoot and identify malfunctions in any type of industrial process environment.


COURSE OBJECTIVESUpon completion of this course, the participants will be able to; • Apply basic troubleshooting search strategies to several

different process problem scenarios and effectively identify a malfunction.

• Identify the components and documentation associated with troubleshooting plant floor systems and their work areas.

• Use the identified components and documentation to identify the root cause of a malfunction.


COURSE OBJECTIVESUpon completion of this course

the participant will be able to: • Identify the various troubleshooting

styles and list the advantages anddisadvantages for each.

• List the elements in the Basic Troubleshooting Strategy.

• Demonstrate the how to utilize machine HMI screen to obtain data.


COURSE OBJECTIVES• Demonstrate the how to utilize

WD machine drawings to obtain data.

• Demonstrate the how to utilize control system indicators to obtain data.

• Demonstrate the how to utilizemachine manuals to obtain data.

• Prepare a maintenance repair document for use in their daily activities.


Housekeeping• Start / Stop Time

• Breaks

• Lunch Break

• Safety ConcernsAdhere to all Plant Safety rules Evacuation Route


TROUBLESHOOTING DEFINED

The Definition of TROUBLESHOOTING is “To operate or serve as a troubleshooter”


TROUBLESHOOTING DEFINED

The Definition TROUBLESHOOTER is;

• A person skilled at solving or anticipating problems or difficulties.

• A skilled worker employed to locate trouble and make repairs in machinery and technical equipment.

• An expert in resolving diplomatic orpolitical disputes a mediator of disputes that are at an impasse.


TROUBLESHOOTING STYLES

GAMBLERS

TESTERS

THINKERS



GAMBLERS

• WANDERERS

• RISK TAKERS

• ODDSMAKERS

• SWAPPERS



WANDERER

• Relies completely on random chance to find the problem!

• Logical sequence not followed!

• Requires little knowledge of troubleshooting strategy!

• Forgets what already has been tested!

• Tends to waste time and effort!


BASIC TROUBLESHOOTINGWANDERER

• Conducts exhaustive search by checking everything in the system!

• Gets lost in the search!

• Lack schematic interpretation and component diagnostic skills!

• Limited system understanding!



• Reconfigures the system to provide new information!

• Very dangerous to both equipment and personnel!

• Likes to experiment with components within a system!

• Must use extreme care not to introduce new faults!

RISK TAKERS



• Rely on knowledge of common fault occurrences!

• Bet on what they think is the correct solution based on symptoms they recognize!

• Troubleshooting requires an increasing level of skill!

• Quickly become Wanderers!

ODDSMAKERS


TROUBLESHOOTING STYLESSWAPPER

• Most encouraged form of gambling!

• Can be very efficient!

• Can quickly get the equipment functioning!

• Exhibits risk-taking behavior!


TROUBLESHOOTING STYLESSWAPPER

• Can damage good parts!

• Limited to supply of spare parts!

• Limited to easily substituted or modular parts!



TESTERS

• SENSORS

• TRACERS

• SPLITTERS


TROUBLESHOOTING STYLESSENSORS

• Likes to look, listen, touch, and smell!

• Valuable strategy for obtaining important information!

• Rarely a stand-alone problem solving method!


TROUBLESHOOTING STYLESTRACERS

• Generally use schematics/prints!

• Performs voltage checks, continuity checks, or signal tracing!

• Start at a known good point in the system and work toward the fault!


TROUBLESHOOTING STYLESTRACERS

• Start from a faulty symptom and search backward to the error’ssource!

• Depends heavily on good test equipment and schematic/print reading skills!


TROUBLESHOOTING STYLESSPLITTERS

• Divide & Conquer!

• Half split method!• Successive approximation!

• Divide a system or circuit in half and check for proper readings, then continue to divide and check!

• Use jumper wires


TROUBLESHOOTING STYLESSPLITTERS

• Disconnect portions of a system or circuit!

• May contribute to confusion because of the induced interactionof components!

• Potential for damage to equipment or injury to personnel!



THINKERS

• READERS

• RECALLERS

• DESIGNERS

• ANALYZERS



• Least skilled form of the “Thinking” approach!

• Highly recommended in many situations!

• Instances still arise to troubleshoot manually!

• Must be able to switch to another style of troubleshooting!

READER



• Rely more on their memory of symptoms and solutions frommany years of experience!

• Troubleshooting needs continual practice!

• Tend to lose troubleshooting skills!

• Solve common problems in familiar systems!

RECALLERS


TROUBLESHOOTING STYLESDESIGNERS

• Use theoretical knowledge to evaluate faults!

• Rarely efficient!



• Highly skilled troubleshooters!

• Use system knowledge and observations (sight) of symptoms to eliminate portions of a system in a logical way!

ANALYZERS


TROUBLESHOOTING STYLESANALYZERS

• Requires a detailed understanding of the system!

• Think before you approach!

• Relies on FUNCTIONAL SEARCH STRATEGIES



• GAMBLERWanderer, Risk Taker, Oddsmaker, Swapper

• TESTERSensor, Tracer, splitter

• THINKERReader, Re-caller, Designer, Analyzer

What is your Troubleshooting style?



• List any advantages to being a SWAPPER.

• List the disadvantage to being a SPLITTER.

• Of all of the Troubleshooting Styles presented, which Style is the least efficient?

• Which Style is most efficient?


THE BASIC TROUBLESHOOTING STRATEGY

REPAIRDOCUMENTATION

SENSORY INPUT FILTERING ACTION

FILTER THE FILTER RE-ACTION

PROBLEMSOLVED

NO

YES



• SENSORY INPUT Comprehension of the elements of observation

• FILTERING Skill set for determining root cause of problems

• ACTIONIntroduction to elements of hardware/software/documentation to implement root cause analysis



• REPAIR Show examples of necessary items

and information needed to affect repair

• DOCUMENTATIONImportance of documenting repairs



SENSORY INPUTWhat is Sensory Input?• Using your senses to gather data on the

problem.

• Every malfunction leaves certain clues as to where the problem occurred and what is needed to start the troubleshooting process.

• The more adept a you are at recognizing the clues, the more information you will have to accurately determine root cause



SENSORY INPUTExamples of sensory input:

• Visual Inspection of Machine

• Reference HMI device

• Listening to the Operator

• Checking Visual Indicators on Modules and Components



SENSORY INPUTHow do you Improve Sensory Acuity?

How does any brilliant idea ever come to people?

• A person takes something he already

knows and thinks about it in a different way.

• Questions like “What if-“ and “Imagine if” spark different avenues of thought.



SENSORY INPUT• When is the best time to do troubleshooting

on a machine? When it is operating correctly.

• What if you could see the machine from

a slightly different perspective every time you look or listen or smell it?

• How much intuitive knowledge would youhave about its processes or its sequencing?



FILTERING Root Cause Concept • Filtering through the different

sensory input should give you a prioritized list of possible root causes.

• This process is done mentally with deduction or, sometimes, induction.



FILTERING Root Cause Concept • Assumption is the enemy of deduction.

Sometimes, problems that occur may have the same symptoms but be an entirely different cause.

• How many times have you found yourself inventing obscure reasons to justify a cause that you just KNOW it has to be and find that it was Something else entirely?



FILTERING • As you learn and gain

experience from a certain machine line, your filtering becomes more acute and your first root cause possibility will tend to be the right one.



ACTIONFrom Thought to Action • After a likely root cause is formulated,

some type of action will be requiredto prove the supposition out.

• We will make suggestions of the actions that need to be taken to trace, diagnose, and/or reference information in the Control system.



ACTION Examples of typical action skills are:

• PLC Logic Tracing • Searching and Cross-Referencing

• Referencing WD Prints • Physical Inspection of Machine

Components

• Trend Data Monitoring



FILTERING THE FILTER The “Other Root Cause” • Sometimes, first impressions

can be incorrect.

• If root cause is not found from the current action, the subsequent possibilities must be explored until a root cause is found.



FURTHER ACTION Re-Action on the Filter • After an alternate root cause is

determined, all steps listed in the ACTION step listed above can be re-used to prove out a possible root cause.



REPAIR FIX IT!!! • Once a definite root cause is

discovered, steps need to be taken to temporarily or permanently repair the machine.

• WD prints can be re-referenced to locate specific sensors or valves.



DOCUMENTATION Words for the Ages • Something often overlooked in the

troubleshooting process is documentation.

• Not only does this help other personnel who may also be troubleshooting that piece of equipment, it will also help YOU when two years have gone by and you completely forget about a problem.



The Basic Troubleshooting Strategy will:

• Make your troubleshooting more effective.

• Eliminate duplicate troubleshooting (Same problem appearing on different shifts)

• Reduce Downtime due to more effectiverepair of malfunctions.



• List three examples of Sensory Input

• Filtering input is a way for you to discover the _______ _______ of the problem.

• What is the final step in the Basic Troubleshooting Strategy?


THE BASIC TROUBLESHOOTING TOOLS

DRAWINGSThe work area drawing depicts a dedicated area of the plant comprised of;• machinery • control equipment• personnel

This area implements the manufacturing process of a specific Component(s)



DRAWINGSDepending on the process, this machinery may consist of various pieces of equipment. Each executes a programmed sequence of operation that puts the part(s) through variousstages of the productionProcess.



DRAWINGS

Area Drawings can be used to Locate equipmentand controls.

Suggestions;• Make notes on drawings

for reference.• Identify control device

locations



DRAWINGS

Drawings can also indicate the various control devices, associated sensor devices, and their tag names.

These tag names can be searched and cross referenced in the working drawings, tag database, the ladder logic, and the HMI I/O status display.



DRAWINGS

Device Drawings can provideThe following data;

• Tag Name

• Node Address

• Wire Labels / Numbers

• Contact Data (NO or NC)



SEQUENCE OF OPERATIONStation 25W Widget Assembler• Operator places Widget Part W21 on conveyor• Widget Part W21 moves into assemble

position, pin clamps open.• Widget Part W21 part present #1 and #2 detected.• Widget Part W24 travels to Assemble position

above Widget Part W21 • Pin Clamps close on Robot Widget Part W21• The assemble process starts • The W-frame press starts down over Widget

Part W21 and Widget Part W24 • W-Frame (Press) continues down and stops

(dwell time).• The clamps extend.• W-Welder Robot spot welds Widget Part W21 and

Widget Part W24• The W-frame press starts up from Widget Part W21

and Widget Part W24 • The clamps retract • Widget Part W-25 ( combined W21 & W24) moves

on to conveyor• Widget Part W-25 clears fixture• Next sequence begins

• Details the sequence of a given machine or process.

• Can be used to identify the area of malfunction.

• Problem is usually in the stepjust before the uncompleted step.



The Human Machine Interface (HMI) is used to communicate with the control system of the machines.

HMI SCREENS



HMI SCREENSThe Human Machine Interface (HMI) is used to communicate with the control system of the machines.

HMI devices are used to;

• Check the operation status of a Machine.

• Permit operator to modify operation.

• Provide alarms and warnings



Typical HMI Screen• Display a system

status. • A form of this

screen is located on almost all machine HMI’s.

HMI SCREENS



• Displays are typically color coded (red and Green) to indicate normal or fault / alarm status.

• Notice how the Man/Auto Ready indicator shows Auto not ready, along with the system local message.

HMI SCREENS



An example of an Alarm Display to view system faults.

• Every message has a event number that is related to a Message Event in the controller logic.

HMI SCREENS



ONLY TRAINED INDIVIDUALS SHOULD ACCESS THE LADDER LOGIC.

• Tracing Ladder logic in the controller requires specialized training in the particular software used by the controller unit.

• Possible machine damage and personnel injury can result from un-authorized modification to the controller logic.

TRACING LADDER LOGIC



A trained individual can use a Controller Workstation or a computer loaded with specific software to; • View the ladder logic

program executing in the controller.

• Modify logic

• Override some signals for diagnostics


Remote Run



An example of a Rung of Ladder Logic.

• An input signal or output signal can be viewed in real time by accessing the ladder logic of the controller unit.




• Tracing a signal in the logic requires good documentation of the various controller logic elements.

• An input signal or output signal can be viewed in real time.

• Specific Signals can be modified (forced) to aid in diagnostics.




CONTROLLER SYSTEM INDICATORS

• Controller Systems usually have Status Indicators located on the Controller and modules.

• Using the indicator LEDs and the Manufacturer manual one can get a clue as to the malfunction




• Controller Systems usually have Status indicators located on the Controller and modules.

• Using the indicator LEDs and the Manufacturer manual one can Get a clue as to the malfunction



CONTROLLER SYSTEM INDICATORSExample : 1756-L55 Controller Module

Status Indicator DescriptionsRUN - Indicates mode of operation:

Solid Green – Processor is running(reading inputs, executing logic, and writing output data to enabled output modules)

Off – Processor is not controlling outputs (processor could be in program mode, test mode, or no power)



CONTROLLER SYSTEM INDICATORSI/O - Indicates status of configured input and output

modules communication:Solid Green – Processor is communicating to its

configured input and output modulesFlashing Green – One or more, but not all,

configured I/O modules is not communicatingFlashing Red – No I/O modules are

communicating or the processor has faultedOff – No configured modules



CONTROLLER SYSTEM INDICATORSFORCE - Indicates the presence and status of

forced I/O:Off – No forces exist in controllerFlashing Yellow – Forces installed, but not activeSolid Yellow – Forces installed and active

RS232 – Communications activity of serial portFlashing Green – Data is being sent or received

through the serial portBAT – Status of memory backup battery:

Solid Red – Battery Level low and needs to be replaced

Off – Battery is OK, or no power



CONTROLLER SYSTEM INDICATORSOK – Status of Controller module:

Green – Controller is OKOff – No power appliedFlashing Red – Minor or major recoverable faultSolid Red – Major non-recoverable controller

fault; must be corrected and reset



MANUFACTURER MANUALS

• Equipment manufacturers oftentimes include a troubleshootingsection in the machine manuals.

• Check the manuals for hints on detecting and preventing malfunctions




• All have different styles. (See this example) Excellent source of information specific to the machine.

• Some provide flowchart style data




• Others provide error code data. (See AB Controller example)

• Use the manuals to interrupt sensory data.

Type Code Fault Description Recovery1 1 The controller pow ered on in Run mode. Execute the pow er-loss handler.3 16 A required I/O module connection failed. Check that the I/O module is in the chassis.

Check electronic keying requirements.View the controller properties Major Fault tab and the module properties Connection tab for more information about the fault.

3 20 Possible problem w ith the ControlBus chassis. Not recoverable - replace the chassis.3 23 At least one required connection w as not

established before going to Run mode.Wait for the controller I/O light to turn green before changing to Run mode.

4 16 Unknow n instruction encountered. Remove the unknow n instruction. This probably happened due to a program conversion process.

4 20 Array subscript too big, control structure .POS or .LEN is invalid.

Adjust the value to be w ithin the valid range. Don’t exceed the array size or go beyond dimensions defined.

4 21 Control structure .LEN or .POS < 0. Adjust the value so it is > 0.4 31 The parameters of the JSR instruction do not

match those of the associated SBR or RET instruction.

Pass the appropriate number of parameters. If too many parameters are passed, the extra ones are ignored w ithout any error.

4 34 A timer instruction has a negative preset or accumulated value.

Fix the program to not load a negative value into timer preset or accumulated value.

4 42 JMP to a label that did not exist or w as deleted. Correct the JMP target or add the missing label.4 82 A sequential function chart (SFC) called a

subroutine and the subroutine tried to jump back to the calling SFC. Occurs w hen the SFC uses either a JSR or FOR instruction to call the subroutine.

Remove the jump back to the calling SFC.

4 83 The data tested w as not inside the required limits. Modify value to be w ithin limits.4 84 Stack overf low . Reduce the subroutine nesting levels or the

number of parameters passed.4 89 In a SFR instruction, the target routine does not

contain the target step.Correct the SFR target or add the missing step.

6 1 Task w atchdog expired. User task has not completed in specif ied period of time.

Increase the task w atchdog, shorten the execution time, make the priority of this task “higher,” simplify higher priority tasks, or move some code to another controller.



MAINTENANCE LOGS

• Maintaining accurate records of System performance parameters of each machine will make problem Identification and malfunction troubleshooting much easier.

• The sooner you identify potential problems will result reduced downtime.



MAINTENANCE LOGS

• Early detection can be achieved by recording a “baseline” of selective parameters such as voltages and average readings for each major deviceand periodically checking for deterioration.

• The baseline data would ideally be collected at the installation of the system once all of the bugs have been worked out. In the event that this data was not collected at installation time, data collected when the system is functioning correctly can be used for the baseline information.



MAINTENANCE LOGS• Once the baseline data is established, periodic

checks of the actual network data can be compared to the baseline and potential malfunctions addressed prior to becoming shutdown situations.

• The next slide an example of a Baseline data form. This is only an example. You may wish to develop your own based on;• Your experience with the network• Operation of particular systems • Certain types of devices


THE BASIC TROUBLESHOOTING TOOLSMAINTENANCE LOGS



Troubleshooting WorksheetFill in the form to help you keep track of your troubleshooting effort. Exercise #

Check ‘Yes’ in each box if it applies. Team #

Start with observation.

Questions Yes No FindingsIs power on?

Is the machine cycling?

Does the cell appear to have stopped mid-cycle?

Is there a fault message on the ‘Bingo’ board?

Are there any fault lights, a fault message, or horn?

Is it a hardware fault or operational fault?

Are there any unusual sounds?

Has the operator offered any information?

Are there any other unusual things happening?

Determine where to find the cause. Narrowing your focus.

Questions What area are you going to focus on?Yes No Findings

Are you going to review more PV+ screens?

Are you going to look at more indicator lights?

Examine the tooling / fixture?

Are you going to view the teach pendant screens?

Are you going to look at weld controller screens?

Are you going to try to cycle in manual?

Are you going to look at the ladder logic?

Do you need a multi-meter or net-meter?

Other (specify):

ACTION I understand what happened. Now I determine what to do about it.Questions

Yes NoFindings

Do you have an idea of what the problem is?

Do you have the knowledge to fix the problem?

Do you have the tools to fix the problem?

Follow all safety practices.

Another example of a Log

Notice that this example Follows the Basic Troubleshooting Strategy• Sensory Input

• Filter

• Action



Basic TroubleshootingStrategy

• Repair

• Documentation

• Adds Section for your Comments and suggestions

REPAIR Fix the problem and verify that it works.

QuestionsYes No Findings

Were you able to fix the problem?

Is the line now in Automatic and ready to run?

Do you feel that the root cause was fixed?

DOCUMENTATION Finishing the effort by documenting your findings for others

QuestionsYes No Findings

Is there a logbook to fill out on this line?

Was it necessary to update files after the repair?

Were the prints updated and valid?

Did you find logic rungs that should be commented better?

LESSONS LEARNED Learning by our mistakes and successes.

Questions FindingsIs there something that could be done to make this fault easier to diagnose and repair?

What could you have seen/done that would have made this repair go faster?



• What would you check to determine the next step in an operation or process?

• What should you check to determine the

Controller Systems is functioningCorrectly?

• What would you use to determine if the malfunction had occurred previously?

• What would you put on a Log for the machine you are responsible to maintain?


THE BASIC TROUBLESHOOTING ReviewGAMBLERS

• Relies completely on random chance to find the problem!• Logical sequence not followed!• Forgets what already has been tested!• Tends to waste time and effort!• Checks everything in the system!• Lack schematic interpretation and component

diagnostic skills!• Reconfigures the system to provide new information!• Very dangerous to both equipment and personnel!• Likes to experiment with components within a system!• Must use extreme care not to introduce new faults!


THE BASIC TROUBLESHOOTING ReviewGAMBLERS

• Rely on knowledge of common fault occurrences!• Bet on what they think is the correct solution based

on symptoms they recognize!• Troubleshooting requires an increasing level of skill!• Can be very efficient!• Can quickly get the equipment functioning!• Exhibits risk-taking behavior!


THE BASIC TROUBLESHOOTING ReviewTESTERS

• Likes to look, listen, touch, and smell!• Valuable strategy for obtaining important information!• Rarely a stand-alone problem solving method!• Generally use schematics/prints!• Performs voltage checks, continuity checks, or signal tracing!• Start at a known good point in the system and work

toward the fault!• Start from a faulty symptom and search backward to

the error’s source!• Depends heavily on good test equipment and

schematic/print reading skills!


THE BASIC TROUBLESHOOTING ReviewTESTERS

• Divide & Conquer!• Half split method!• Successive approximation!• Divide a system or circuit in half and check for proper

readings, then continue to divide and check!• Use jumper wires• Disconnect portions of a system or circuit!• May contribute to confusion because of the induced

interaction of components!• Potential for damage to equipment or injury to personnel!


THE BASIC TROUBLESHOOTING ReviewTHINKERS

• Least skilled form of the “Thinking” approach!• Highly recommended in many situations!• Instances still arise to troubleshoot manually!• Must be able to switch to another style of troubleshooting!• Rely more on their memory of symptoms and solutions

from many years of experience!• Troubleshooting needs continual practice!• Tend to lose troubleshooting skills!• Solve common problems in familiar systems!


THE BASIC TROUBLESHOOTING ReviewTHINKERS

• Use theoretical knowledge to evaluate faults!• Rarely efficient!• Highly skilled troubleshooters!• Use system knowledge and observations (sight) of

symptoms to eliminate portions of a system in a logical way!

• Requires a detailed understanding of the system!• Think before you approach!• Relies on FUNCTIONAL SEARCH STRATEGIES


THE BASIC TROUBLESHOOTING Review

• The work area drawing depicts a dedicated area of the plant comprised of; machinery , control equipment, and Personnel

• Area Drawings can be used to Locate equipment and controls.

• Drawings can also indicate the various control devices, associated sensor devices, and their tag names

DRAWINGS



• Details the sequence of a given machine or process.• Can be used to identify the area of malfunction.• Problem is usually in the step just before the uncompleted

step.

SEQUENCE OF OPERATION



• The Human Machine Interface (HMI) is used to communicate with the control system of the machines.

• HMI devices are used to; Check the operation status of a Machine, Permit operator to modify operation, and Provide alarms and warnings

• Displays are typically color coded (red and Green) to indicate normal or fault / alarm status.

HMI SCREENS



ONLY TRAINED INDIVIDUALS SHOULD ACCESS THE LADDER LOGIC.

• Tracing Ladder logic in the controller requires specialized training in the particular software used by the controller unit.

• Possible machine damage and personnel injury can result from un-authorized modification to the controller logic.

• Use a Controller Work station or a computer loaded with specific software to; View the ladder logic program,modify logic, or Override some signals for diagnostics

Trace Ladder Logic



• Controller Systems usually have Status indicators located on the Controller and modules.

• Using the indicator LEDs and the Manufacturer manual one can Get a clue as to the malfunction




• Equipment manufacturers often times include a troubleshootingsection in the machine manuals.

• Check the manuals for hints on detecting and preventing malfunctions

• Manuals provide error code data.



THE BASIC TROUBLESHOOTING Conclusion Module One

Using the Basic Troubleshooting Strategy improveYour troubleshooting ability and result in:

• Increased production

• Reduced down

• Confident Workforce


THE BASIC TROUBLESHOOTING Conclusion Module One

Thank you for your attention.

Keep this process in mind during the second ModuleWhen we will address specific Machines on your plant floor.

basic troubleshooting pwr pt

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