Correcting Continuous Area Accumulation

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There are a few easy solutions that should be checked before getting into a more serious level of troubleshooting.

  • First, make sure that everything is clean. Start with the transparent belts. Make sure there isn't any dirt, debris, or film that would cause the values to continuously accumulate. Also check to see if the accumulation only occurs in bursts. This might happen if the seam of the belt (where the two ends of the belt are sealed together to make a loop) may be coming loose or has dirt collected on it.
  • Next, check all the mirrors to make sure they are clean. Sometimes dirt, debris, dust, hair, etc. will collect on the mirrors' surfaces. There are three mirrors to clean. Two are underneath the belts, and the third is in the housing. Static charges sometimes cause material to collect on these surfaces.
  • Check the lens of the camera. This is also a place where material can collect and cause the LI-3100C to accumulate values.
  • Next, inspect the light bulbs. Sometimes, dark spots can collect on the bottom of these lamps due to the mercury drops that are injected during the lamp's manufacturing process. If the bulb has dark spots on the bottom, rotate the bulb so that the spots are no longer on the bottom.
  • Another common problem is when the Cal Adjustment screw is turned too far. Use a screwdriver and turn the screw all the way to the left (counter-clockwise). If this was the problem, the numbers should stop. Then twist the knob towards the middle (not too far or the numbers may start accumulating again). Recalibrate the LI-3100C with the Calibration Disks after you manipulate the Cal Adjustment screw.

Most of the time, one of the above suggestions will be the solution for this issue. If not, there may be some more in-depth troubleshooting suggestions that can be performed. Contact LI-COR if the above steps did not resolve the issue. A helpful piece of information to have would be the instrument’s serial number. There have been several versions and revisions of the LI-3100C Leaf Area Meter.