4 Operation Model 3190
4-6 Teledyne Analytical Instruments
4.8 “SetL” mode in the LED display
When you turn on the unit, it displays “8.8.8.8” for a couple of seconds. This
is to have an inspection that all segments of the display are all right. After the
first two seconds, the LED display will show “SetL” and alternate with a
countdown starting at 34.0. This countdown is to let the electronics settle and
do a zero calibration of the electronics. Flowing “zero” gas or a sensor is not
needed for this instrument adjustment. It is only an electronic zero
calibration. The sensor is automatically disconnected by the 3190 hardware
during this mode. As soon as the countdown reaches 0.00, the analyzer will
go back to the normal mode of operation and the sensor is reconnected.
When the concentration rises above a point between 2000 to 3000 ppm
(it changes from sensor to sensor) there are a few seconds where the display
freezes. This is due to an automatic gain change to low gain. When the
concentration drops and crosses a point between 3000 and 1500 ppm (it
changes from sensor to sensor) the display will show “SetL” and alternate
with a countdown of 30 seconds. This is due to an automatic gain change to
high gain. It takes longer for the electronics to settle when switching to the
high gain than when switching to low gain, that is the reason why the count-
down only appears when the sensor reading is going down and not up.