1. Présentation du test.

This test is used to calibrate the red LED top of the film carrier which is used for the detection of film end.
A sensor, which is opposite the LED top, receives part of the signal and ascertains a light level. This level corresponds to any film present in the film carrier. When the film is inserted, the light level decreases. When it is the end of the film, the hole makes the light level go up to the calibrated value, and thus the scanner stops the scanning process.
If the LED is incorrectly calibrated, the detection of film end may not function, which can interrupt an end of scanning / pre-scanning too early (all the images are not displayed) or cause an overtorque (since the motor continues to turn whereas the film is hung in the cassette).

2. Test conditions.

This test relates to the APS film carrier inserted in the scanner.
The APS film carrier must be inserted in the scanner to carry out this test.
No film must be inserted in the film carrier for this test.
The acceptance of the test is automatic.
The value of calibration of the LED is saved in the file im1500data.ini, in chapter FILM_CARRIER_APS, with line FILM_DETECTION_THRESHOLD.

3. Pre-requirements.

To ensure that the LED will not change of position ( because of vibration for example), which could influence the intensity of the luminous signal, and thus the value of calibration of the LED, the LED must be glued : Cyanoacrylate Glue is recommended.

4. Test realisation.

Click on RUN to execute the test. A message indicates to withdraw any film from the film carrier . Click on OK then after a few seconds, the value of calibration of the LED will be displayed on the screen. This value will be saved.

5. Test acceptance.

There is no higher limit for this test, on the other hand the lower limit is fixed at 20.
Note : a value of 200 functions as well as a value of 40, since the software makes a comparative measurement between the value without film and the value with film.

6. Other affected tests.

If the LED value of calibration is incorrectly calibrated (for example: calibrated value = 180, true value = 40), that can have an negative impact on all the tests where the scanner is needed for scanning a film (the film may not be detected properly and thus incorrectly taken). But that does not influence directly on any tests results.

7. Trouble shooting.

The value of calibration is below the lower limit (20) : This means that the light signal is insufficient. Try to polish the LED to increase the signal, or to direct it differently so that the signal is more centreed on the sensor..

Several consecutive measurements give very different values : this means that the signal is unstable. Initially try to block any external light which can have an influence on the gauged value. Check that the LED does not move in its housing. As a last resort, the interface board of the film carrier can be failing.

It should be noted that a test in mode debug DEBUG LED POLLING (accessible only on PROD mode) makes it possible to make 100 consecutive measurements and to observe the variation of the value.