Systems Approach
An instrument system consists of three major components: The operator, the environment,
and the instrument. A failure in, or poor performance of, an instrument system can be the
result of difficulties in any one of the system’s three major components.
The operator: The end-user typically makes the initial decision that a failure or malfunction
has occurred problems can be due to such factors as incorrect or improper operation,
or incorrectly set controls.
The environment: The total environment surrounding the instrument and operator
problems can be related to environmental and other factors such as temperature, drafts,dirt, vibration, incorrect electrical supply, electrical or chemical interference, input
exceeding the dynamic range, bad reagents, or bad electrodes.
The instrument: The device that performs a task such as measurement or control.
Failures of the device fall into two general categories: (1) non-electric (e.g., loose or broken
connections, dirt, corrosion, or mechanical wear. These are the most probable sources
of instrument failures); and (2) electronic (a component or circuit failure). In general., the
electronic portion of an instrument is the most reliable part.)
The first problem of troubleshooting is to determine whether the fault is in the operation,
environment, or instrument component of the instrument system. The purpose of the methodology
of troubleshooting is to gather information about the poor performance or failure of an
instrument system in a logical and systematic manner. Questions to ask include the following:
● How does the system normally behave?
● What are the conditions of failure?
● What are the symptoms caused by the failure?
● What is the cause of the failure?