53
Optical zero
adjusting knob
7.2.3 Optical zero adjustment method (Optical balance method)
When the sample cell is reassembled after having been removed for cleaning or the like, this
adjustment should be carried out before use. Following is the adjustment procedure.
(1) First carry out electrical zero adjustment.
With the power turned off, detach the connectors CN2 and 3 (for 1st component) and CN4 and
5 (for 2nd component) leading from the detector which are connected with the main PCB (2).
Next, turn on the power and calibrate the zero point using ZERO and CAL keys.
(2) Turn off power, connect the connectors CN2 and 3 (1st component) and CN4 and 5 (2nd
component), and turn on power again. Supply dry nitrogen from the sample gas inlet and wait
until the indication stabilizes.
(3) Set up the optical zero adjustment mode as
in 6-3. The following indications will
appear on the main and sub indicators of
the analyzer front panel.
(4) Operate the optical zero adjusting knob so
that the numeric value on the main indica-
tor approaches zero (within
±
10).
(5) Operate the dimmer plate so that the
numeric value on the sub indicator ap-
proaches zero.
(6) Repeat steps (4) and (5) to bring the numeric values on the main and sub indicators as close to
zero as possible.
A mistake in this adjustment will cause problems in measurement.
NO
Main indicator:
Input signal
from measurement
detector
Sub indicator:
Input signal
from interference
compensating detector
Dimmer plate
CAUTIONS
