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Service manual
4.3.7.2. Darkness counts
The program shows the current integration times for each lter. On running the test, the analyzer positions the
covered lter and measures the darkness counts with each of the integration times. Each time an optical reading
is taken, the analyzer subtracts these darkness counts from the count numbers measured to obtain the light
intensity. The program shows the values obtained and issues the corresponding alarms in case of anomaly.
The values should be around 4100 - 4300. All the count numbers shown by the tests given as follows have the
darkness counts subtracted.
4.3.7.3. Repeatability without moving the lter wheel
To perform this and the following tests, the base line and darkness count test must have rst of all been perfor-
med. This test takes absorbance readings during 1 minute with the lter wheel in xed position. The technician
can choose the rotor well on which he wishes to take the readings and ll it with the liquid he desires. He can
choose which wavelength he wishes to use. The test can also be performed with the lter covered. When the
readings end, the screen graphically displays the count numbers obtained and the absorbances with regard to
the corresponding base lines. The program also shows the averages and/or standard deviations of the count
numbers and the absorbances.
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