Thermo Scientific 410i Instruction Manual page 224

System Description
Electronics
Bench Heater Board
Pre-amp Board
Assembly
Digital Output Board
I/O Expansion Board
(Optional)
Front Panel
Connector Board
8-8 Model 410i Instruction Manual
The bench heater board provides connections for the optical bench heater
resistors and optical bench temperature thermistor.
The optical bench temperature is measured with a thermistor. The voltage
across the thermistor is applied to the main processor and used to display
and control the temperature of the optical bench. The main processor
compares the voltage to a set point and controls the 120VAC power to the
bench heater resistors to maintain a constant bench temperature.
The pre-amp board assembly amplifies the signal from an infrared sensor
that receives light passing through the sample gas. The preamplifier gain is
adjusted by the main processor to bring the signal amplitude within a
normal operating range. The output of the pre-amp board is fed to the
measurement interface board. Wires from the pre-amp board apply power
to the infrared source resistor. The pre-amp board assembly is mounted on
top of the optical bench.
The digital output board connects to the motherboard and provides
solenoid driver outputs and relay contact outputs to a connector located on
the rear panel of the instrument. Ten relay contacts, normally open (with
power off), are provided, which are electrically isolated from each other.
Eight solenoid driver outputs (open collector) are provided along with a
corresponding +24VDC supply pin on the connector.
The I/O expansion board connects to the motherboard and adds the
capability to input external analog voltage signals and to output analog
currents via a connector located on the rear panel of the instrument. It
contains local power supplies, a DC/DC isolator supply, a sub-processor
and analog circuits. Eight analog voltage inputs are provided with an input
voltage range of 0V to10VDC. Six current outputs are provided with a
normal operating range of 0 to 20 mA.
The front panel connector board interfaces between the motherboard and
the function key panel and graphics display. It serves as central location to
tie the three connectors required for the function key panel, the graphics
display control lines, and the graphics display backlight to a single ribbon
cable extending back to the motherboard. This board also includes signal
buffers for the graphics display control signals and a high voltage power
supply for the graphics display backlight.
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