Models 3940 and 3949 ________________________________________________________________Installation and Set-Up
2 - 2
2.3 Remote Data Output
a. RS-232 Data Output
The Model 3940/3949 incubator is equipped with an RS-
232 Serial Communication Interface for the remote transmis-
sion of temperature and humidity data. A terminal strip is locat-
ed on the back of the incubator for convenience. Refer to
Figure 2-2 for terminal pin identification.
b. Remote Alarm Contacts
Remote alarm connections are also included on the termi-
nal strip (Figure 2-2) providing Normally Open (N.O.) and
Normally Closed (N.C.) contacts. C is the Common terminal.
The remote alarm will activate when either the incubator’s tem-
perature or humidity go out of the set alarm limits.
2.4 Power Connection
See the serial tag on the side of the unit for electrical spec-
ifications, or refer to the electrical schematics at the end of this
manual.
Connect the incubator to a grounded, dedicated
circuit. The power cord connector is the mains
disconnect device for the incubator. Position the
incubator so the unit can be easily disconnected.
For Model 3940, plug the provided 10 ft. power cord with
the NEMA 14-20 plug into the power outlet connection on the
back of the cabinet, then into the grounded dedicated electrical
circuit.
For Model 3949, the electrical junction box is located on
the rear top section of the incubator. With the junction box
switch OFF, connect the incubator to an adequate power source.
2.5 Start-Up
When the humidification system is operational, the incuba-
tor may be started. Preset the controls as follows:
Overtemp Safety Thermostat . . . . . . . . . . . . . Fully Clockwise
Undertemp Safety Thermostat . . . . . . Fully Counterclockwise
Main Power Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ON
Humidity Controller . . . . . . . . . . . . . . . . . . . .Desired Setpoint
Temperature Controller . . . . . . . . . . . . . . . . . .Desired Setpoint
Door Heater . . . . . . . . . . . . . . . . . . . . . . . . . .40% (factory set)
For best overall performance of the incubator, the refrigera-
tion switch should be turned on for most applications. When
running Low or No humidity at high temperatures, the refriger-
ation switch may be turned off.
The defrost switch must be turned on when the
temperature setpoint is 10°C, or below.
2.6 Setting the Overtemp Safety Thermostat
Allow the chamber temperature and humidity to stabilize
then set the overtemp safety thermostat as follows:
1. Turn the overtemp control knob slowly counterclock-
wise until the audible alarm sounds and the overtemp
indicator lights.
2. Turn the overtemp control knob clockwise approximate-
ly two units on the scale. The alarm should be silenced
and the overtemp indicator light should go out. The
overtemp safety thermostat is now set a few degrees
above the control temperature setpoint. When the cham-
ber temperature rises to the overtemp control point, the
alarm system will activate, power to the heaters will shut
off, and the chamber temperature will be maintained at
the overtemp control point.
When an overtemp condition occurs, the cause must be
determined and corrected before normal operation under the
main temperature controller can be resumed.
Note:
When the chamber temperature control setpoint is
changed, the overtemp safety thermostat must be reset to
accommodate the change.
Figure 2-2
