Light Measurement Troubleshooting

Troubleshooting your Light Measuring System: Before sending your Light Measuring System in for possible repairs, you may want to utilize the simple checklist below to determine if returning your instruments for service is necessary.


  1. Check your Calibration Certificate to make sure that the sensitivity factor being used is correct for the detector/filter/input optic model & serial number combination that you are attempting to use. All components (model & serial numbers) listed on the calibration certificate must be used during measurement for accurate readings. PLEASE NOTE: Filters/input optics should not be swapped without changing the calibration factor.

  2. Confirm the AA batteries in the ILT1400 are still fresh & in the proper position. Only rechargeable NICAD batteries should be used in ILT1700 (standard C batteries may leak & cause extensive damage to your meter); confirm that they are fully charged per instructions in your manual. If using a power source, double check to make sure it is functioning properly.

  3. Confirm that a proper zero was done for the ILT1400 & ILT1700 detectors.

    1. DARK: cover sensor/detector with opaque object, wait 10 seconds, press zero, wait 5 seconds until meter finishes.

    2. AMBIENT: no cover on sensor/detector, light to be measured should be off, press zero, wait 5 seconds until meter finishes, turn on source to be measured.

  4. Confirm that your meter/detector system has been calibrated within (at least) the past 12 months as Calibration Certificates are only valid for up to 12 months. NOTE: meters measuring high levels of UV may require re-calibration more frequently. You will want to check your previous re-calibration to see how much the system changed during your last calibration cycle. If the unit was “out of tolerance” by a significant amount, you may want to use a shorter calibration cycle.

  5. If your ILT1700 is “locking up” (displays freeze), try the “Re-initialization Procedure” on page 31 of the ILT1700 manual.

  6. If your belt radiometer shows a black display after emerging from conveyor oven & then shows measurements a few minutes afterward, the unit may have been overheated. Although these readings should be fine, the meter should be “cooled down” between sessions. Eventually the overheating will cause the unit to degrade faster than normal.


Click here for more information on returning your light meter for service.

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