LI-COR LI-850 Replacing

Replacing the Source and Detector in
the LI-8x0 Analyzers and LI-8100/A
This document describes how to replace the optical source
and detector on the LI-830, LI-850, and LI-870 gas analyzers,
legacy LI-800, LI-820, LI-840, and LI-840A gas analyzers, and
the LI-8100/A Automated Soil CO
Gas
Analyzer
Source Detector
LI-850/870 800-902 800-918
LI-830 800-902 800-916
LI-840/A 800-902 800-906
LI-820 800-902 800-903
LI-800 800-902 800-903
LI-8100/A 8100-902 800-906
Contents
LI-800, LI-820, LI-840/A, LI-830, LI-850, and LI-870
LI-8100/A Source and Detector Replacement
LI-800, LI-820, LI-840/A, LI-830, LI-850, and
LI-870
The LI-800, LI-820, LI-840/A, LI-830, LI-850, and LI-870
optical source and detector may need to be replaced if one
fails. The life expectancy of the source is typically >20,000
hours, or >2 year of continuous operation, but this will vary
depending upon the number or warm-up cycles, vibration,
and other factors. Typically, detectors need to be replaced
rarely, if ever.
Disassembly
You'll need #1 or #2 Phillips screwdriver and a clippers or
utility knife. The installation, including calibration, may
take an experienced technician 30 minutes to 1 hour. If the
instrument has been running recently, the bench may be
hot to the touch. Let it cool for 5 or 10 minutes after power-
ing off if needed.
Note: Be sure that you are properly grounded to avoid elec-
trostatic discharge that can damage the electronics. Use an
anti-static wrist strap, electrostatic discharge grounding mat,
Flux System.
2
Part Numbers
14 cm 5 cm
Bench Bench
800-904 n/a
800-904 n/a
800-904 n/a
800-904 800-905
800-904 800-905
800-904 n/a
or occasionally touch bare metal that has a clear path to
ground, such as an unpainted computer case.
Power off the gas analyzer and remove the top cover
1
(LI-800, LI-820, LI-830, LI-840/A and LI-850) or open
the case (LI-870 only).
The LI-800, LI-820, LI-830, LI-840/A and LI-850 top cover
is held in place by 6 screws. Loosen the screws and lift
off the cover. If there is a ribbon cable connecting the top
panel, be careful not to strain it. The LI-870 is opened by
removing two screws that hold the case closed; then
remove four screws that secure the optical bench cover.
2 Unplug the source and detector ribbon cables from
the source and detector.
1
3
3 Lift the optical bench out of the foam insulation.
Replacing the Optical Source
With the optical bench free of the case (except the tubing),
you can remove the source from the optical bench.
Remove the tube from the source.
1
The simplest way is to cut the tubing as close to the hose
barb as possible.
Installation Guide
1