Newport 300 Series - Model 300 Series Operating Checklist

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3.6.2 Model 300 Series Operating Checklist
The following steps should be followed when operating a Model 300 Series
Temperature Controller.
a) Check the AC voltage selection of the unit to be sure that it is compatible
with the outlet to be used. All units are factory preset for operation from
180–250 V
AC
.
b) Connect the temperature sensor and TE module to the 15-pin output
connector.
c) Check that the proper temperature sensor bias is selected.
d) Turn on the AC power switch and the unit will start-up with the output
to the TE module off. The display will be in the PRESET mode.
e) Before setting any values on the DISPLAY select the operating mode,
R/T or I
TE
.
f) Change the display to the LIMIT display mode and set the maximum
current allowed to the TE module. The limit set point is adjusted using
the recessed LIMIT SET screw.
NOTE: The maximum current is specified by the manufacturer and
must not be exceeded or damage to the TE module may occur.
g) If the operating set-point has not been set or needs to be changed,
select the PRESET display mode and use the control knob to set the
correct value. The operating temperature, resistance or TE current is
set before turning the OUTPUT on.
h) The OUTPUT can now be turned on and the Model 300 Series Tempera-
ture Controller will automatically control the temperature or I
TE
. Push
the OUTPUT switch once to turn the current on to the TE module and a
second time to turn the current off. If there is an error condition the
current will not turn on and the ERROR indicator LED will come on. If
this occurs verify that the temperature sensor and TE connections are
correct. After an ERROR condition has occurred the OUTPUT switch
must be pushed once to reset the control circuitry. After the fault is
corrected and the circuitry is reset the OUTPUT switch can be pushed
a second time and the output current will turn on.
i) When the output is turned on the temperature should be monitored for
overshoot and stability. The gain of the control loop can be adjusted to
accommodate various thermal time constants of different laser diode
mounting arrangements. Figure 5 shows three possible gain adjust
settings for a given system. When the gain setting is too high the
temperature overshoots the temperature setpoint (Tset) and oscillates
around it. If the gain is set too low the temperature never reaches the
setpoint. For most telecommunication packaged laser diodes the gain
will be at the minimum gain setting which is in the farthest counter
clockwise position. For larger mounts the gain adjust setting may have
to be increased by turning the adjustment screw in a clockwise direc-
tion. If there is too much overshoot in the temperature the GAIN
adjustment screw on the back panel must be adjusted.
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