VICI D-4-I - Manual (Page 9)

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DISCHARGE switch and indicator
Controls power to the pulse supply module. When the switch is on and the
module is connected, high voltage is generated by the unit and is present
at the detector electrodes. The indicator will not light if the detector is in
the standby mode, or if the pulse supply is not connected to the controller.
The indicator flashes until the discharge has been established, then glows
steadily.
TEMPERATURE control and indicator
Sets the temperature (°C) of the detector heater block. The indicator is
steadily on when maximum power is being applied to the heater, steadily off
when no power is applied, and regularly blinking on/off when the set tem-
perature has been established.
Note that due to the fail-safe mechanism designed into the temperature
controller, the heater will not operate if mains power is applied before the
heater is connected or if the detector is too cold (< 0°C). If the heater is dis-
connected with mains on, the unit must first be turned off to restore control
of the heater; if the unit is operated in a very cold environment, the detector
should first be gently warmed without power applied.
The fail-safe mechanism will also act under any condition resulting from loss
of control (e.g., over-heating, RTD failure, etc.). If proper procedures have
been followed and the controller will not heat the detector, there is cause to
suspect that the fail-safe mechanism has been activated. Consult the
factory or an authorized representative.
Heater control may be lost during periods of fast
electrical transients. The unit will self-recover.
MODE switch
Determines the operational mode of the controller and unzeroes the signal
output (see discussion under ZERO push button). This switch changes
the bias voltages supplied to the electrodes as required for each detection
mode. In the PDHID mode the bias voltages are set at -200 and the
linearization circuit is inactive; in the PDECD mode the bias voltages are
internally controlled and the detector output is linearized. (Note that the
PD-D4-I cannot operate in the PDECD mode.)
RANGE switch
Determines the full-scale range of the electrometer: 100 nA @ 1X, or
10 nA @ 10X. In PDECD mode, the high detector background current
normally restricts operation to the 1X range.
CURRENT switch (Not used with the D4-I)
Sets the standing current in PDECD mode. Pressing at the top increases
the current, pressing at the bottom decreases the current.
ATTENUATION control
Determines the attenuation factor for the recorder output.
Introduction