ELTRA CS-2000, Service Manual

Page: 76 / 160

Adjustments
76
The outputs of the IR cells (IR base lines) are factory set at 8V when the paths are new and
clean. The peaks come down starting from 8V coming down to a minimum voltage (at the peak
maximum) and they go back to the 8V baseline after completion of combustion. The 8V IR-base
line is obtained through preamplifier adjustment only.
In real operation, with growing contamination resulting in gradually weakened radiation reaching
the detector, the IR cell output base lines will move down to levels below 8V depending on the
grade of contamination. The (negative output) peaks of the cell will also change to smaller
amplitude.
The base line is not regulated any more.
Due to a recalculation formula, the base lines on the screen are always zero volts, the peaks
are positive and they are always of equal amplitude and surface (for same sample and same
weight) regardless the path contamination, regardless the cell base line level, and regardless
the cell output peak amplitude. Consequently the integrated value (of the peak on the screen)
remains the same and of course also the analyses results remain constant at any grade of
contamination.
–
When loading the UNI software select from now on "New cell" mode.