Product

• Lotem^® 400
• Lotem 400 Xpose
• Lotem 800

Error Message

Carriage reach position without edge detection

Cause

The problem can be caused by one of the following:

• Dirt on one of the following:
  • lens
  • drum
  • light detector
  • edge detection strip
• Poor plate attachment
• Software version, missing patch
• Incorrect parameters:
  • Fufu Air Pump
  • Plate Thickness
  • Focus Relative Move for Edge Detection
  • Height Start Image Area
  • Width Start Image Area
  • Plate on Drum Height Axis Absolute Position Error
• Focus motor functionality
• Laser power
• Edge detection upper and lower limit values
• Beam 0 diode
• Cable and fiber connections to edge detection and MCF boards
• Edge detection or MCF board

Solution

Check edge detection performance

1. From the PC Controller application, run the edge detection test. Accuracy should be 0.01 mm.
2. While the edge detection test is running, check the MCF slave sproc zoh_average.out, and check stability of the values received during drum rotation.
   If the data value varies, it indicates that the edge detection reading is not stable due to one of the following being incorrect:
• focus
• power
• strip location

Steps 8-10 below describe how to resolve these issues.
Note: Step 2 must be completed while the edge detection test is running or the results will be inaccurate.
3. Check the reliability and accuracy of the edge detection test:
1. Load a plate.
2. Expose two intensity strips along the drum (height axis) on each side of the plate.
3. Unload the plate.
4. Repeat steps a-c, 5 to 10 times.
5. Process the plate.

When the loading system is properly aligned, and edge detection is properly aligned, a 10 µ line is not widened to more than double its width.

Troubleshooting

Throughout the procedure below, after any modification or change of parameters, check the edge detection performance again, as described above. If the error message persists, continue the troubleshooting procedure.

1. Clean the following:
• Lens
• Drum—with vacuum on, clean drum vacuum holes
• Light detector
• Edge detection strip—clean with alcohol
2. Check plate attachment to the drum.
1. Confirm that the vacuum pump is turned on, and correct if required.
2. If hot spots or bubbles occur in the leading edge of the plate, use the following procedures to resolve these problems.
• Moving focus motor to solve hot spots
• Hot spots troubleshooting
3. If positive plates are used, check the Fufu Air Pump parameter in the registry to confirm that it is closed, and correct if required.
   Note: Many edge detection problems result from fufu air contamination due to oil, water, and other dirt.
4. Check that the Plate Thickness parameter is correctly defined in the media definition, and correct if required.
5. In the Expose registry, check that the value of the Focus Relative Move for Edge Detection parameter is –100 for 0.15 and 0.2 mm plates.
6. If your plate is close to the maximum allowed plate size, confirm that the Height Start Image Area parameter is smaller than the expected edge detection parameter. Reduce the Height Start Image Area parameter by 3 to 5 mm, if required.
7. In the Expose registry, check the Plate on Drum Height Axis Absolute Position Error parameter. This parameter represents the area along the drum in which the edge is expected to be found. The default of 20 can be increased to 40 or 60.
   Note: This parameter is important, especially if you do not center the plate in the semi-manual machine.
   If you increase the number too much over 50, you may encounter further edge detection errors due to drum dirt or obstacles. For example, if you have a full-sized plate and the number is set to 60, the edge detection could detect the drum edge as a plate.
8. Check the focus motor functionality by checking the coarse and the fine HP adjustments and the focus motor function.
9. Check the power using the test panel. Increase or decrease the laser power according to the stability of the results.
10. In the edge detection registry, check the lower and upper limit values for strips 1 and 2, which define the window in where the edge is found around the drum.
11. If you have a 24-diode device, check the functionality of beam 0. This beam determines proper edge detection. If required, in the edge detection registry, select beam 23 instead of beam 0, or, replace diode 0.
    Note: If you have a 12-diode device, only beam 0 determines proper edge detection. Ensure that beam 0 is functioning, and replace it, if required. Ensure that all diodes are functioning, and replace any defective diode, if required.
12. Check the cable and fiber connections to the following boards.
    • Edge detection
    • MCF
    If there are no problems with the connections, replace the boards.
13. On the connector on the MCF side (pins 8 and 15), measure the ED analog output voltage. With laser 0 ON at about 40 mW, the output should be approximately 0 V.
    Note: The output on the drum should be approximately 5 V.
    If the voltage is not correct, replace the edge detection board.

Technical contact(s)

Mario Amir

Submitted by

Efri Eller

Date submitted

15 Jul 2003