The localization of faults in electronic equipment is often the most difficult part of the service work, and no written
instruction on the subject can replace familiarity with the instrument and knowledge of its construction. The built-in self
diagnostics of the microprocessor will help facilitate systematic troubleshooting of the system, however, this section
cannot cover every possible problem. The most likely sources of trouble are listed together with the appropriate
Before beginning troubleshooting procedures, check that the proper power source is being applied to the system. Also
check that the sensor and its cable are undamaged. A digital multimeter can be used for checking voltages and current
By using the test mode (Mode O) of operation, the built-in simulator and front panel controls and display it is possible to
simulate input parameters. This can be used to verify proper internal functioning of the analog to digital conversions,
processing, outputs and alarms.
The built-in self diagnostics can display two types of error messages; operational and equipment malfunctions.
Calculation results in questionable valve.
Insufficient data (a required input parameter not available)See sensor troubleshooting section.
Excessive input noise this can be caused by excessive stray voltage in the process where the sensor is
Input Measurement out of range.
Calculated results out of range.
Read-only-memory of processor fails. Check sum. Permanent program failure.
Random-access-memory failure (Unable to write or read back correctly).
Identification error. During every program cycle the input board I.D. is checked.
A circuit board in wrong slot.
Display switch failure.
Not programmed for P.C.
Board identity (wrong or no input card).