Product

Trendsetter-based devices

Symptoms

Oval shaped voids in the image appear near the leading edge of the plate. These artifacts appear as light sections on negative plates (shown), and as dark sections on positive plates (not shown). Around the edges of the ovals, a checkerboard or crosshatch pattern may be visible.

Click on the images below to view close-ups of this artifact

These artifacts occur near the leading edge of the plate when a thin bubble of air exists between the plate and the drum, moving the surface of the plate closer to the write laser. Under certain circumstances, this can cause the head to go out of focus and transfer an incorrect amount of laser power onto the plate.

Cause

Possible causes:

• Improper clamping
• Incorrect roller pressure
• Too much plate curl
• Autoloader option: the drop distance is too large

Solution

1. Ensure that plates are not being loaded with too much force against the output device's registration pins.
2. Load, image, and process a new plate: type load m <xxx> s <yyy> ms <z>
   (xxx = mainscan dimension in mm; yyy = subscan dimension in mm; z = number of plates in the stack)
3. In the thermal head, check the focus laser mode for the media you are imaging.
   1. In Service Shell, select the Device Monitor applet, and then select either MCE (master head) or MCE2 (slave head) from the Device Tree.
   2. Type the command:
      prm hazardous media enable
      (This allows you to make changes to the media parameters, if necessary)
   3. Type the commands:
      redirect enable
      (This displays the TH2>> prompt)
      eng
   4. To view the current value of the focuslasermode parameter, type the command:
      set med <n> focuslasermode
      where <n> is the index number of the media you are using.
4. Make sure that the focuslasermode parameter is set to 0.
5. Check the LE clamp gap.
6. Check that the plate does not have any dents or other defects.
7. Check that the roller is going down evenly and with the correct pressure.
8. If the artifact persists, escalate to your PSS.

See also

Troubleshooting TH2 focus errors

Technical contact(s)

Kyle Good

Date submitted

26 Jan 2006