1. Test Overview.

This test is used to calibrate the Green LED at the bottom of the film carrier / gate which is used to detect film presence.
A sensor which is opposite to the LED receives a signal and determines the light level with no film present. When a film is inserted into the gate the receiver senses the drop in light and therefore knows that a film has been inserted. The "SCAN" button on the DKS then becomes active.
If the LED is incorrectly calibrated the Scan button on the DKS can remain "Grey" (not usable) even if a film is inserted into the gate. It may work intermitantly but this is due to the ambient light within the room.

2. Conditions of the test.

This test relates to the 120 film carrier inserted in the scanner.
The 120 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 calibration value of the LED is saved the file im1500data.ini, in chapter FILM_CARRIER_120, with line FILM_DETECTION_THRESHOLD .

3. Requirements.

To ensure that the LED will not change of position ( because of vibration for example), which could influence the intensity of the light signal, and thus the calibration value of the LED, the LED must be glued : recommended glue: cyano-acrylate.

4. Realisation of the test.

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 calibration value of the LED will be displayed on the screen. This value which will be saved

5. Acceptance of the test.

There is no higher limit for this test, on the other hand the lower limit is fixed to 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 calibration value of the LED is incorrectly calibrated for example: calibrated value = 180, true value = 40) this can have an negative impact on all the tests where a film needs to be scanned (the film may not be dedected and thus incorrectly taken). But this does not influence directly any of the test results.

7. Trouble shooting.

The calibration value 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 centered on the sensor.

Several consecutive measurements give very different values :This means that the signal is unstable. Try initially to block any external light which can have an influence on the calibratred value. See if the LED does not move in its housing. As a last resort, the film carrier interface board can be failing.
It should be noted that a test in mode debug DEBUG LED POLLING (accessible only one mode PROD) makes it possible to make 100 consecutive measurements and to observe the variation of the value.