Shellab SMI39-2 - Manual (Page 13)

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3/ Check connections to sensor.
4/ Check calibration
– using independent thermometer, follow
instructions in section 5.6.
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 Overtemperature 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.
3/ Is ambient 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 Overtemperature sensors, then trace wires or
tubing between sensors and controls.
5/ Calibration sensitivity
– call Customer Service.
6/ Overtemperature set too low – be sure that its setting is more than 5
degrees over desired set point; check if pilot light is on continuously;
turn controller knob completely clockwise to see if problem solved then
follow instructions in section 5.7 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
– 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.
2/ See if ambient is fluctuating
– check for adjacent open doors or
HVAC duct openings, stabilize ambient conditions.
Display and reference thermometer don’t
match
1/ Calibration error – see section 5.6.
2/ Temperature sensor failure – evaluate if pilot light is operating
correctly.
3/ Controller failure
– evaluate if pilot light is operating correctly.
4/ Allow at least 24 hours to stabilize at set point temperature.
5/ Verify that reference thermometer is certified.
Can't adjust set points or calibration
1/ Turn entire unit off and on to reset.
2/ If repeatedly happens, call Customer Service.
Calibrated at one temperature, but not at
another
This can be a normal condition when operating temperature varies
widely. For maximum accuracy, calibration should be done at or as
close to the set point temperature as possible.
MECHANICAL
Door not sealing
1/ Check physical condition of gasket.