8
TROUBLESHOOTING
Problems encountered with any constant
temperature chamber will most frequently be
related to temperature control. Before proceeding
with detailed troubleshooting, be certain that the
Low Limit and High Limit controls are adjusted
properly. If the limit controls are set too close or
beyond the operating temperature, the incubator
may be consistently going into alarm. This will
result in erratic temperature control. First, the
symptoms and possible causes will be listed for
quick reference. Later, the remedies will be
suggested.
WARNING
HAZARDOUS HIGH VOLTAGE CONDITIONS EXIST
INSIDE THE CONTROL PANEL. UNPLUG LINE
CORD AND TURN "OFF" LINE SWITCH BEFORE
REMOVING THE COVER. ONLY QUALIFIED
ELECTRICAL INSTRUMENT PERSONNEL ARE
AUTHORIZED TO PERFORM TROUBLESHOOTING
AND/OR SERVICING.
SYMPTOMS AND POSSIBLE CAUSES:
Freeze-up or gradual drop in chamber
temperature:
No air circulation in chamber; inoperative fan (see
Remedy 1)
Heater (see Remedy 2)
Power Supply PCB Assembly (see Remedy 3)
RTD Temperature Probe (see Remedy 3, Step D
and/or Remedy 4).
Temperature variations at set point (poor
control):
Excessive ambient temperature variations (see
Remedy 10)
Compressor Relay failure (see Remedy 12)
No air circulation in chamber; inoperative fan (see
Remedy 1)
RTD Temperature Probe Location (see Remedy
5)
Ice buildup on evaporator coils (see paragraph on
"Defrosting")
RTD Temperature probe (see Remedy 3, Step D
and/or Remedy 4).
Power Supply PCB Assembly (see Remedy 3)
.
Press the HIGH/LOW LIMIT key twice. The green
"Low Temperature Alarm/Setpoint" indicator should
be lit. Use the UP or DOWN arrow keys to select
your limit value. Then press the ENTER key. If the
LOW LIMIT value you have selected is above the
operating setpoint temperature, the incubators'
alarm will activate.
NOTE
SOFTWARE VERSION 2.00 HAS A 30-MINUTE
DELAY FOR THE LOW AND HIGH ALARM TO AVOID
NUISANCE ALARMS CAUSED BY DOOR
OPENINGS.
SERVICING
WARNING
SERVICE SHOULD BE PERFORMED ONLY BY
QUALIFIED SERVICE PERSONNEL. EXERCISE
CARE AS LINE VOLTAGE IS PRESENT IN THE
CONTROL COMPARTMENT.
If it is ascertained, after review of the
Troubleshooting Section, that refrigeration service
is needed, contact Technical Services.
In any communication with Thermo, include the
model and serial numbers from both nameplates.
