Specifications

SECTION 8 TROUBLESHOOTING
8.1 Troubleshooting - General
Symptom
Display does not light up.
Process display shows (- - -)
or ‘HHHH’
Probable Cause & Corrective Action
No power, blown fuse.
Process display shows LLLL or
counts down scale when
temperature is rising.
About 30% error.
No heat
Display blinks; entered values
change.
Open thermocouple circuit Shorting terminals 1
and 2 should indicate temperature at back of case.
Repair or replace thermocouple.
Check for reversed thermocouple.
Wrong thermocouple type connected or internal
range jumper in wrong position. Check serial tag for
sensor type and then check probe. Consult manual
for jumper location for desired range and then
check unit and sensor.
Incorrect heater wiring, wrong output module.
Check for cause and correct the components
Electromagnetic interference (EMI).
To eliminate high voltage spikes, separate sensor
and controller wiring from “dirty” power lines.
Ground heated devices. Suppress all coils and con-
tacts. See section on Electrical Noise.
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