Thermo Scientific Precision Premium PR305040G, Operating Manual

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7-2 Precision Premium Oven Thermo Scientific
Section 7
Troubleshooting
Symptom Probable Cause Action
No power Unit not plugged in or turned on Plug in or turn on
Defective circuit breaker Replace circuit breaker
Oven temperature
erratically high
Defective control thermocouple Replace control thermocouple
Failure to heat
Set temperature less than actual
temperature
Refer to Operation
Defective control thermocouple Replace control thermocouple
Poor heater connections
Tighten connections at terminal
strip
Defective heater element
Check heater resistance at
schematic at back of manual.
Replace heater unless approxi-
mately the same as schematic.
Defective controller Replace controller
Defective solid state relay
Refer to schematic and replace
relay or safety relay
Over Temperature Device
Disengaged or Defective
Replacement of the Over
Temperature Device is to be
performed by factory authorized
personnel only. Disconnect
power and contact Technical
Services.
Alarm LED stays on
and control is higher
than set temperature
Set temperature has been changed
to a value less than the actual tem-
perature minus the high alarm limit.
Wait for actual temperature to
cool to the set temperature
Defective controller Replace controller
Defective solid state relay or safety
relay
Refer to schematic and replace
relays
Set display shows
“EEE”
Set temperature has been changed
to a value less than the actual tem-
perature minus the high alarm limit
Wait for actual temperature to
cool to the set temperature
Defective control thermocouple Replace control thermocouple
Faulty or broken connections
Check thermocouple connec-
tions at rear of temperature
controller
Temperature different
from independent
thermometer
Calibration off set needs adjusted.
Begin by setting offset to 0.
See Display Offsets.