Shellab SCO12WE-2 - Manual (Page 18)

17
Unit will not heat over a temperature
that is below set point
1/ confirm that fan motor is moving and that amperage and
voltage match data plate
– check fan motor motion in shadow box
and feel for air movement in chamber
2/ confirm that set point is set high enough ,turn OTP
counterclockwise and see if heating light or safety light comes on
3/ check connections to sensor
4/ check calibration
– using independent certified reference
thermometer, follow instructions in sections 5.4 and 5.8
Unit will not heat up at all
1/ verify that controller is asking for heat by looking for heating
light
– if pilot light is not on continuously during initial start up there
is a problem with the controller
2/ check amperage
– amperage should be virtually at maximum
rated (data plate) amperage
3/ do all controller functions work?
4/ is the OTP set high enough?
– for diagnostics, should be fully
clockwise with the pilot light never on
5/ has the fuse/circuit breaker blown?
Indicated chamber temperature
unstable
1/ ±0.1 may be normal
2/ is fan working?
– remove top panel and verify movement of
cooling fan in center of shadow box
3/ is ambient room temperature radically changing
– either door
opening or room airflow from heaters or air conditioning? –
stabilize ambient conditions
4/ sensor miss-located, damaged, or wires may be damaged -
check mounts for control and OTP sensors, then trace wires
between sensors and controls
5/ calibration sensitivity
– call Customer Service
6/ OTP set too low – be sure that OTP set point is more than 5
degrees over desired Main set point; check if OTP pilot is on
continuously; turn controller knob completely clockwise to see if
problem solved then follow instructions in section 5.8.D for correct
setting.
7/ electrical noise
– remove nearby sources of RFI including
motors, arcing relays or radio transmitters
8/ bad connection on temperature sensor or faulty sensor
–
check connectors for continuity and mechanical soundness while
watching display for erratic behavior; check sensor and wiring for
mechanical damage
9/ bad connections or faulty capacitor
– check connectors for
mechanical soundness and look for corrosion around terminals or
signs of arcing or other visible deterioration
Will not maintain set point
1/ assure that set point is at least 5 degrees over ambient room
temperature
2/ see if ambient is fluctuating