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...8 MAINTENANCE
8.6 Microprocessor Unit Error Messages
The instrument incorporates an automatic self-diagnostic
checking facility for detection of input and output errors. If such a
fault occurs, one of the error messages detailed below is shown
on the dot matrix display.
'CHAN 1 INPUT ERROR'
This error message is usually caused by an open circuit
sensor input allowing the input to drift outside the range of
±400 mV. This may be due to any of the following:
a) Loss of solution flow through the flowcell breaking the
electrical connection between the electrode pair.
b) Low level of salt bridge solution in the reference electrode.
c) Open circuit electrode internally, e.g. broken connection,
blocked liquid junction in reference electrode etc.
d) Broken electrical connections between the sensor and the
Microprocessor Unit sensor input.
e) Sensor coaxial plugs not correctly inserted.
'TEMP INPUT ERROR'
'PRT OUT OF LIMITS'
'TEMP REF. ERROR'
'THIRD LEAD ERROR'
The above four error messages refer to electrical problems with
the temperature sensor input – usually an open or short-circuited
connection.
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