Digital Equipment LA600 MultiPrinter, Field Service Manual

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Selected AGC Position
Lineal
Movement Area of the Print Head
1
1
2
3
2 2
4
Horizontal Encoder
1 / 120 “
Specific Printer Functions
4-1 4-2
4. Specific Printer Functions
4.1.2 AGC Procedure
4.1 Print Gap Adjustment
4.1.1 Principle
The print head carriage is mounted on two parallel guide rails which provide for
a precise movement over the whole print range in horizontal direction. The
lower rail is built up as an excentric shaft. The excentre arrangement is driven
by a stepper motor (AGC-Motor). Those both elements are responsible for the
precise adjustment of the print gap, that is the distance between the print head
top and the the paper respectively the platen assembly.
In conjunction with print gap adjustment the following three different procedures
have to be distinguished:
S
Calibration of the print gap adjustment mechanics, called A utomatic G ap
C ontrol Adjust ment ( AGC Adjust )
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Automatic print gap adjustment, called A utomatic G ap C ontrol ( AGC )
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Programmed print gap adjustment, called P rogrammed C opy C ontrol ( PCC )
AGC Adjust and AGC are performed by means of the AGC Procedure.
AGC Adjust can be called up via the operator panel and is performed after
installation of a Personality Module with a new firmware revision.
AGC is automatically performed after changing from online - offline – online, Position
and after changing of the paper path.
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The carriage is permanently moved in horizontal direction by a distance of
PCC is performed if the command PCC is sent to the printer. For refernce see
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The time period for horizontal movement is permanently recognized by the
“Quick Reference” of the printer control commands in the appendix of the user firmware and checked against a reference value.
manual.
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Simultanously to the above shuttling the printhead / carriage is moved
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At the start the printhead/carriage is horizontally positioned at the AGC
1/120” to the left and right hand side of the AGC Position.
towards the platen assembly by means of the AGC drive until the print head
top gets in contact with the platen assembly or the surface of the paper.
S
The contact of the printhead top with the surface of the paper or the platen
assembly is recognized by the firmware by checking the time interval for
positioning within the shuttling process.
Note:
Horizontal Drive Error will not be checked by this procedure. If the
movement of the print head is to hard the printer use 0.5 A more.