Product

• Thermal 1.0/1.7 Heads

Error

Symptoms

Unable to detect the edge of the plate, or the image shifts randomly in the subscan direction. May also get “Focus error detected at X inches” or “Unable to learn focus” errors.

Cause

The focus laser system was not able to accurately detect the edge of the plate. The problem may also be caused by a faulty or damaged power box-to-head cable connection.

Solution

1. The focus laser is very susceptible to ablation. If on-site, clean the lens to make sure there is no ablation on the lens. For the procedure, see TH1/1.7 Lens Cleaning Procedure (77-0125A)
   Note: Be sure to order the Encoder cleaning kit (04-0014A) (includes 04-0012B lens cleaning kit).
2. Ensure that there is no dirt or damage on the edge detect strip. If on-site, also confirm the drum epos position.
3. Check for any batch media variation. Try with a different batch of media, and check for variation in surface reflectivity and focus sum values. There should not be any visible media surface color variation.
4. Check the thermal config files to get the factory-calibrated fheadcal value: http://techplanet.creo.com/thermal_config/.
5. Position the head over a plate loaded on the drum, and then issue the >> focus cal reflect command. For the integrated value of fheadcal, it should produce a value of sr such that the sum = ~1000. The sr value returned should be close to the media’s specified value. Please check the media technical notes (it might also be helpful to check the following two head parameters: head onthresh should be close to 1000, and head offthresh should be close to 0).
6. If necessary, find the plate edge manually, and then run the edgesim.spt field script to verify whether the media has a good plate edge. Tip: Use slow carriage move commands.
7. Check the power, 9-pin, and 20-pin ribbon cable connections at the head and in the power box. Replace any cable that appears to be faulty or damaged.

Note: The fheadcal value should remain the same as the factory setting, so that the remote support specialist can diagnose the problem properly. In the future, the procedure maybe different, but for now, always set the fheadcal value to the factory setting.

See also

• Th1/1.7x Field Scripts
• Th1/1.7x Cleaning Procedures

Additional info

The fheadcal value should remain the same as the factory setting, so that the remote support specialist can diagnose the problem properly. In the future, the procedure maybe different, but for now, always set the fheadcal value to the factory setting.

Technical contact(s)

Dusty Sarter
Rick Hsu

Submitted by

Rick Hsu

Date submitted

18 Feb 2002