LI-COR LI-840/A Manuals

LI-840A CO2 /H2 O GAS ANALYZER Instruction Manual

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 CO2 Flux System. Gas Analyzer Part Numbers Source Detector 14 cm Bench 5 cm Bench LI-850/870 800-902 800-918 800-904 n/a LI-830 800-902 800-916 800-904 n/a LI-840/A 800-902 800-906 800-904 n/a LI-820 800-902 800-903 800-904 800-905 LI-800 800-902 800-903 800-904 800-905 LI-8100/A 8100-902 800-906 800-904 n/a Contents LI-800, LI-820, LI-840/A, LI-830, LI-850, and LI-870 1 LI-8100/A Source and Detector Replacement 3 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, or occasionally touch bare metal that has a clear path to ground, such as an unpainted computer case. 1 Power off the gas analyzer and remove the top cover (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. 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. 1 Remove the tube from the source. The simplest way is to cut the tubing as close to the hose barb as possible. 1 Installation Guide