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Intermec EasyCoder 501 – Service Manual Ed. 7
Chapter 8
8.1 Different Models
8. Print Unit
Presently, the EasyCoder 501 printers are manufactured with three
types of print units:
• The standard direct thermal/thermal transfer print unit.
• The LinerLess print unit with plasma coating and a special
platen roller to prevent label from sticking to the print unit.
• A special print unit exclusively used in connection with the
Ribbon Save Device (see Chapter 10).
For information on earlier types of print units, please refer to
editions 1-4 of this Service Manual.
The print unit is partly integrated with the optional liner/batch
takeup unit, which is more thoroughly explained in Chapter 9. The
main parts of the print unit are:
• The rubber-coated platen roller drives the media forward
under the printhead and provides the necessary counter-
pressure.
• The stepper motor drives the platen roller via one belt,
and the ribbon assist roller and the ribbon rewind unit
via another, whereas the liner drive roller is idle, unless a
liner/batch takeup kit is fi tted, see Chapter 9.
• The tear bar makes it easier to tear off continuous or
preperforated stock. It is also used for peel-off operation.
• The label stop sensor (LSS) controls the media feed and
checks for out-of-media conditions.
• The printhead produces the heat that melts the “ink” on the
ribbon or blackens the direct thermal media in patterns that
make up the letters, graphics, or bar codes.
• The headlift mechanism presses the printhead against the
thermal media or transfer ribbon, or lifts the printhead to
allow media and ribbon load.
The print unit is a self-contained module and attached to the print-
er’s center section using four #T20 Torx screws. There are also a
number of cables running from the print mechanism to the CPU
board (see Chapter 17.4), which are not illustrated.
The liner drive roller (fi tted underneath the platen roller) is driven
by a belt to the stepper motor of the liner/batch takeup mechanism,
and the ribbon rewind unit is driven by a belt from the motor of the
print unit. These belts have to be removed before the print unit can
be pulled out.
8.2 Main Parts