1. Test overview.

This test is used to verify that the belts of the 120 film carrier is sufficiently tightened. This test is similar in its operation than with of MOTOR INTENSITY. This one having been made beforehand, the primary tension therefore correct. If the test 120 motor intensity fails, this means that the film carrier has a problem.
The software always controls the current sent to the motor, which represents the image of the tension on the belts: the more the belts are tightened, the greater the effort will be to turn the motor, therefore the amount of current required will be larger.
The advance of film during the scanning must be maintained as steady as possible, as the software controls the amount of current sent to the motor according to the efforts required. The current must be as stable as possible, however variations may occur due to the " off centred effect " of the gears.
The tension measurement of the belts is made in both directions of the motor (corresponding to the prescan and the scan).
If the belts of the film carrier are not sufficiently tightened, the film can slip during the scanning and this can generate a incorrect framing of the images. On the other hand, if the belts are overtightened, the risk of overtorque (overloaded motor) will become greater.

2. Test conditions.

This test relates to the 120 film carrier inserted in the scanner.
The 120 film carrier must to be inserted in the scanner to carry out this test.
No film is necessary for this test.
The acceptance of the test is automatic.
No parameter is saved.

3. Pre-requirements.

For this test, it is necessary to mechanically tighten the 2 belts of the film carrier. Thist is done normally with an adequate tool (tension checker tool), but it can be done by hand.

• · If the tool is available : Remove the protective plate of the film carrier (the belts become visible). Loosen the lock -nut (1) (at the back of the film carrier). Place the tool between the lower and the higher plate (2), then press on the belt using the tension checker tool. Tighten or slacken the belt while operating the eccentric (3)(behind the lock-nut). When the good tension is found, Retighten the lock-nut (1).
  Do the same exercise with the other belt.



• · If the tool is not available : remove the protective plate of the film carrier (the belts become visible). Lloosen the lock-nut (1) (at the back of the film carrier). Tighten or slacken the belt while operating the eccentric (3) (behind the lock-nut) until finding a correct correct. Do the same exercice with the other belt. Tighten the lock-nut (1) and to launch the test to check that the tension is correct.
  

4. Test realisation.

Click on RUN to execute the test. The motor will turn during 15 seconds in one direction then 15 seconds in the other direction (these 15 seconds correspond to a turn of film belt carrier.
At the end of the test, in the result window, a red and blue curve will be displayed (corresponding to both directions of rotation of the test). In the execution window, quantified results for each curve will be displayed. The test will automatically be accepted or rejected according to these 2 curves results.

5. Test acceptance.

The software is used mainly for 3 criteria (for each direction of rotation, that is to say 6 in total) to accept or reject the test :

• The average of the curve: must lie between 60 and 72,6
• The maximum of the curve: must be lower than (real average + 15%)
• The minimum of the curve: must be higher than (real average - 15%)

6. Other affected tests.

If the tension of the belts of the 120 film carrier is modified in significant proportions, the following tests should be remade :

• 120 cal play.
• 120 cal encoder 2.
• 120 cal RGB IR.

If the tension of the belts were modified very little (for example, the average passed from 71 to 62), it is probably not useful to remake all these tests

7. Trouble shooting.

• The average is too low or too high : : This means that the belts are not enough or overtightened. In this case, they should either be retightened, or slacken. Several tests can be necessary to find the correct tension.


• The average in one direction is much weaker than in the other direction : this means that the gear motor is damaged, it should be changed.


• The minimum or the maximum is outside the spec : This is due to the gears off centred effect. Check that the both gears(motor and film carrier) are correctly assembled on their axis (that they run smoothly). Check that all the gears of the film carrier turn freely. Also note that the more tension on the belts, the greater the off centred effect will show (creating a significant undulation on the curve).


• During the test, the motor stops, the LED scanner passes to the red : this means that the belts are overtightened , and that there was overtorque during the test. Pull out then insert the film carrier to remove the defect, slacken the belts, then start again the test.