Basic Troubleshooting Pwr Pt

BASIC TROUBLESHOOTING
STRATEGY
Developing a
Functional Search Strategy for an
Effective 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 OBJECTIVES
This 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 OBJECTIVES
Upon 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 OBJECTIVES
Upon completion of this course
the participant will be able to:

• Identify the various troubleshooting
styles and list the advantages and
disadvantages for each.

• List the elements in the Basic
Troubleshooting Strategy.

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


COURSE OBJECTIVES
WD machine drawings
to obtain data.

control system indicators
to obtain data.

machine manuals to obtain data.

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

Housekeeping
• Start / Stop Time

• Breaks

• Lunch Break

• Safety Concerns
Adhere 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 or
political 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!


WANDERER
• Conducts exhaustive search by checking
everything in the system!

• Gets lost in the search!

• Lack schematic interpretation and
component diagnostic skills!

• Limited system understanding!


RISK TAKERS
• 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!


ODDSMAKERS
• 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!


SWAPPER
• Most encouraged form of gambling!

• Can be very efficient!

• Can quickly get the equipment
functioning!

• Exhibits risk-taking behavior!


SWAPPER

• Can damage good parts!

• Limited to supply of spare parts!

• Limited to easily substituted or
modular parts!


TESTERS

• SENSORS

• TRACERS

• SPLITTERS


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

• Valuable strategy for obtaining important
information!

• Rarely a stand-alone problem
solving method!


TRACERS
• 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!


TRACERS
• Start from a faulty symptom
and
search backward to the
error’s
source!

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


SPLITTERS
• 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


SPLITTERS
• 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!


THINKERS

• READERS

• RECALLERS

• DESIGNERS

• ANALYZERS


READER
• 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!


RECALLERS
• 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!

DESIGNERS

• Use theoretical knowledge to
evaluate faults!

• Rarely efficient!


ANALYZERS
• Highly skilled troubleshooters!

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


ANALYZERS

• Requires a detailed understanding
of the system!

• Think before you approach!

• Relies on
FUNCTIONAL SEARCH STRATEGIES


What is your Troubleshooting style?
• GAMBLER
Wanderer, Risk Taker,
Oddsmaker, Swapper

• TESTER
Sensor, Tracer, splitter

• THINKER
Reader, Re-caller,
Designer, Analyzer


• 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
SENSORY INPUT FILTERING ACTION

FILTER THE FILTER RE-ACTION

NO

YES
PROBLEM
DOCUMENTATION
SOLVED REPAIR


STRATEGY
• SENSORY INPUT
Comprehension of the elements of observation

• FILTERING
Skill set for determining root cause of problems

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


STRATEGY
• REPAIR
Show examples of necessary items
and information needed to affect repair

• DOCUMENTATION
Importance of documenting repairs


STRATEGY
SENSORY INPUT
What 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

STRATEGY
SENSORY INPUT
Examples of sensory input:

• Visual Inspection of Machine

• Reference HMI device

• Listening to the Operator

• Checking Visual Indicators on
Modules and Components


STRATEGY
SENSORY INPUT
How 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.

STRATEGY
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 you
have about its processes or its sequencing?


STRATEGY
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.


STRATEGY
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?

STRATEGY
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.


STRATEGY
ACTION
From Thought to Action

• After a likely root cause is formulated,
some type of action will be required
to 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.


STRATEGY
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

STRATEGY
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.


STRATEGY
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.


STRATEGY
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.


STRATEGY
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.

STRATEGY
The Basic Troubleshooting Strategy will:

• Make your troubleshooting more
effective.

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

• Reduce Downtime due to more effective
repair of malfunctions.


STRATEGY
• 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
DRAWINGS
The 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)


DRAWINGS
Depending 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 various
stages of the production
Process.


DRAWINGS
Area Drawings can be
used to Locate equipment
and 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 provide
The following data;

• Tag Name

• Node Address

• Wire Labels / Numbers

• Contact Data (NO or NC)


SEQUENCE OF OPERATION Station 25W Widget Assembler
• Details the sequence of a •
•
Operator places Widget Part W21 on conveyor
Widget Part W21 moves into assemble
position, pin clamps open.
given machine or process. • Widget Part W21 part present #1 and #2 detected.
• Widget Part W24 travels to Assemble position
above Widget Part W21
• Can be used to identify the •
•
Pin Clamps close on Robot Widget Part W21
The assemble process starts
• The W-frame press starts down over Widget
area of malfunction. Part W21 and Widget Part W24
• W-Frame (Press) continues down and stops
(dwell time).
• Problem is usually in the step •
•
The clamps extend.
W-Welder Robot spot welds Widget Part W21 and
Widget Part W24
just before the uncompleted • The W-frame press starts up from Widget Part W21
and Widget Part W24
step. • The clamps retract
• Widget Part W-25 ( combined W21 & W24) moves
on to conveyor
• Widget Part W-25 clears fixture
• Next sequence begins


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


HMI SCREENS
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.

• Provide alarms and warnings

HMI SCREENS
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. BASIC TROUBLESHOOTING

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.


TRACING LADDER LOGIC
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.


A trained individual can
use a Controller Work Remote
Run

station or a computer
loaded with specific
software to;
• View the ladder logic
program executing in
the controller.

• Modify logic

• Override some signals
for diagnostics

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


Example : 1756-L55 Controller Module
Status Indicator Descriptions
RUN - 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)


I/O - Indicates status of configured input and output
modules communication:
Solid Green – Processor is communicating to its
configured input and output modules
Flashing Green – One or more, but not all,
configured I/O modules is not communicating
Flashing Red – No I/O modules are
communicating or the processor has faulted
Off – No configured modules


FORCE - Indicates the presence and status of
forced I/O:
Off – No forces exist in controller
Flashing Yellow – Forces installed, but not active
Solid Yellow – Forces installed and active

RS232 – Communications activity of serial port
Flashing Green – Data is being sent or received
through the serial port
BAT – Status of memory backup battery:
Solid Red – Battery Level low and needs
to be replaced
Off – Battery is OK, or no power

OK – Status of Controller module:
Green – Controller is OK
Off – No power applied
Flashing Red – Minor or major recoverable fault
Solid Red – Major non-recoverable controller
fault; must be corrected and reset


MANUFACTURER MANUALS

• Equipment manufacturers often
times include a troubleshooting
section 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


Type Code Fault Description Recovery
1 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.

• Others provide error Check electronic keying requirements.
View the controller properties Major Fault tab
and the module properties Connection tab for

code data. 3
3
20
23
Possible problem w ith the ControlBus chassis.
At least one required connection w as not
more information about the fault.
Not recoverable - replace the chassis.
Wait for the controller I/O light to turn green

(See AB Controller 4 16
established before going to Run mode.
Unknow n instruction encountered.
before changing to Run mode.
Remove the unknow n instruction. This probably
happened due to a program conversion

example) 4 20 Array subscript too big, control structure .POS or
process.
Adjust the value to be w ithin the valid range.
.LEN is invalid. 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.

• Use the manuals to
4 31 The parameters of the JSR instruction do not Pass the appropriate number of parameters. If
match those of the associated SBR or RET too many parameters are passed, the extra
instruction. ones are ignored w ithout any error.
4 34 A timer instruction has a negative preset or Fix the program to not load a negative value into
interrupt sensory 4 42
accumulated value.
JMP to a label that did not exist or w as deleted.
timer preset or accumulated value.
Correct the JMP target or add the missing label.

data. 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
Remove the jump back to the calling SFC.

a JSR or FOR instruction to call the subroutine.

4 83 The data tested w as not inside the required limits. Modify value to be w ithin limits.
4 84 Stack overflow . Reduce the subroutine nesting levels or the
number of parameters passed.
4 89 In a SFR instruction, the target routine does not Correct the SFR target or add the missing step.
contain the target step.
6 1 Task w atchdog expired. User task has not Increase the task w atchdog, shorten the
completed in specified period of time. 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 device
and 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


MAINTENANCE LOGS


Troubleshooting Worksheet
MAINTENANCE LOGS
Fill in the form to help you keep track of your troubleshooting effort. Exercise #

Check ‘Yes’ in each box if it applies. Team # Another example of a Log
Start with observation.
Questions Yes No Findings
Is power on?
Is the machine cycling?
Does the cell appear to have stopped mid-cycle?

Is there a fault message on the ‘Bingo’ board?
Notice that this example
Are there any fault lights, a fault message, or horn? Follows the Basic
Is it a hardware fault or operational fault?

Are there any unusual sounds?
Has the operator offered any information?
Troubleshooting Strategy
Are there any other unusual things happening? • Sensory Input
Determine where to find the cause. Narrowing your focus.

Questions What area are you going to focus on?
Are you going to review more PV+ screens?
Yes No Findings
• Filter
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?
• Action
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.

MAINTENANCE LOGS
REPAIR Fix the problem and verify that it works.

Yes No Findings
Basic Troubleshooting
Questions
Were you able to fix the problem? Strategy
Is the line now in Automatic and ready to
run?
• Repair
Do you feel that the root cause was fixed?

• Documentation
DOCUMENTATION Finishing the effort by documenting your findings for others
• Adds Section for
Yes No Findings
Questions
Is there a logbook to fill out on this line? your Comments and
Was it necessary to update files after the suggestions
repair?

Were the prints updated and valid?

Did you find logic rungs that should be
commented better?

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

• What should you check to determine the
Controller Systems is functioning
Correctly?

• 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?

Review
GAMBLERS
• 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!

Review
GAMBLERS
• 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!


Review
TESTERS
• 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!

Review
TESTERS
• 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!


Review
THINKERS
• 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!


Review
THINKERS
• 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


Review
DRAWINGS
• 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


Review
SEQUENCE OF OPERATION
• 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.


Review
HMI SCREENS
• 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.


Review
Trace Ladder Logic
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

Review
• 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


Review
• Equipment manufacturers often times include a
troubleshooting
section in the machine manuals.
• Check the manuals for hints on detecting and preventing
malfunctions
• Manuals provide error code data.


Conclusion Module One
Using the Basic Troubleshooting Strategy improve
Your troubleshooting ability and result in:

• Increased production

• Reduced down

• Confident Workforce


Conclusion Module One
Thank you for your attention.

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


Basic Troubleshooting Pwr Pt

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