Source, Detector, and Optical Path Replacement
Instructions for the LI-800, LI-820, LI-840, and LI-8100
The LI-800 (discontinued), LI-820, and LI-840 Infrared Gas Analyzers and the LI-8100 Automated Soil CO
common optical bench configuration; the source and detector on this optical bench can be easily replaced should they fail. These
instructions detail how to change out the source, detector and/or optical bench on any of these four instruments. There is also a
discussion about how to adjust the calibration coefficients and check the linearity of the analyzer's response (LI-840 and LI-8100
only) at the end of this instruction sheet. Check the table below to make sure that you have the correct replacement part(s) for your
instrument, and then proceed to the appropriate section for installation instructions.
A Phillips head screwdriver and a 1/2" open end wrench are the only tools needed to replace the source and/or detector in all instru-
ments.
LI-800 GasHound CO
Analyzer
2
LI-820 CO
Analyzer
2
LI-840 CO
/H
O Analyzer
2
2
LI-8100 Automated Soil CO
Part Number
Description
800-902
Source
800-903
Detector
800-904
Path 14 cm
800-905
Path 5 cm
800-906
Detector
8100-902
Source
LI-800 GasHound CO
The LI-800 Replacement Detector retains a default configuration for compatibility with earlier versions of the embedded software.
LI-800 embedded software versions 1.0 and 1.1 are compatible only with the PC Communications Software versions 1.4 and below
(contact LI-COR to upgrade your embedded software). The embedded software version number is printed on a label on the chip
located between the inlet and outlet tubing to the optical bench. To determine which version of the PC Communications Software you
are using, simply start the LI-800 program and view the title bar. If your LI-800 has embedded software version 1.0 or 1.1, proceed
with the instructions below, ignoring Step 11.
1.
Turn the LI-800 off. Let the optical bench cool for about 10
mintues. Loosen the six screws on the LI-800 top panel and
remove the cover.
2.
Unscrew the tube retaining nuts on the inner air port fittings.
Remove the tubing from both air ports. Leave the tubing
connected to the source and detector housings.
3.
There are ribbon cables (Figure 1) connected to the circuit
boards on the source and detector housings. Pull straight out
on the connector that is attached to each ribbon cable. The
optical bench can now be removed from the foam casing.
Flux System
2
LI-800
Analyzer Source/Detector/Optical Path Replacement
2
LI-820
X
X
X
X
X
X
X
X
Ribbon cable
connector
1
Flux System share a
2
LI-840
X
X
X
1
Source
Detector
5 cm bench
connector
LI-8100
X
X
X
Ribbon cable
connector
Air tube
fittings
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