Possible cause |
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After the edge is detected and before starting the plot the head has to "learn" the profile of the plate to ensure that the focus system will be able to track. Normally this is done for 2 swaths.
This error may occur due to:
- Head not installed correctly
- Focusing on clamps or on the outside of the plate
- Bump or dents on the plate
When focus learn problems are reported by the head, 95% of the time it is not a head problem. Some possible causes:
- Focusing on clamps or on the outside of the plate
- Bump or dents or other plate loading problems (very common on TS NEWS devices), such as a bubble created close to the LEC
- Incorrect media, sr, lasermode, actuator mode, and so on.
- Carriage problems, such as too-high acceleration
- Head not installed properly
- Head failure of focus system
- For Lotem Quantum devices:
- For TS NEWS devices:
- Double-picking or incorrect
basethickness parameter.
- The
learnskip parameter may be enabled. To disable it, type
MCE> set focus learnskip false
- In Print Console, the “Edge detect” option may not be set to Always. To correct this, in Print Console, select: Device > EdgeDet > Options and select Always.
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Suggested action |
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If the error occurs intermittently:
Note: For Lotem Quantum devices, check the firmware version of the MCE and the head. MCE firmware v1.28xx and head v1.02 are not compatible. In this case, the error will be intermittent and the plate profile (focus learn table) will look very good. For details see Software versions on Lotem Quantum platesetters.
- Enable verbose for the focus subsystem. Type:
TH2> eng
TH2> vbs enable foc 7
TH2> redirect pass
Note: This may slow the system down.
- Ask the customer to continue running plates. Monitor the system for a while.
- If the system has Service Shell, and if verbose does not slow the customer too much, obtain the information from the Service Shell logs.
- If the system has Splot only, and if verbose does not slow the customer too much, minimize Splot and capture the terminal display (if you are connected remotely you will be able to observe the display).
- Observe the results of the focus learn table to see how well the plate is attached to the drum.
Note: If while monitoring the system there is a focus learn failure, you will have to retrieve the focus learn table. Type the following commands:
TH2> eng
TH2> foc get table
This will display the last learned table. For more information, see Troubleshooting TH2 focus learn issues.
- Depending on the results of the table, troubleshoot as required or follow the next procedure.
If the error occurs most of the time:
- Ask the customer if this happens with an specific plate thickness or plate size, or only when doing proofing for the Lotem Spectrum.
- Check that the head is installed correctly, the media is set up correctly, and so on.
- Load a plate.
- Disable the write laser to perform focus tests on the plate. Type:
TH2> eng
TH2> set sys laserenable false
- Run a plot.
TH2> vbs enable foc 7
TH2> redirect pass
MCE/MPE> plot 1
- If necessary, retrieve the focus learn table by typing:
TH2> eng
TH2> foc get table
- If the focus learn fails, inspect the focus learn table. Based on the results of the focus learn table, troubleshoot as required.
- To determine if the failure is occurring due to a problem at the beginning of the plate, shift the beginning of the plot in both on the subscan and mainscan directions. On the MCE, use the command
MCE> plot shift 100 100
On the MPE, use the commands
MPE> plot shift mssa 4000 and
MPE> plot shift sssa 4000
These commands shift the beginning of the plot 10 cm both in the subscan and the mainscan direction.
- Run another test plot to see if the focus learn passes. If does, then shift the plot in only one of the directions. This will help you confirm your predictions from the focus learn table.
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