AMT Datasouth XL 300 SERIES, Maintenance Manual

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1.3: PRINTER INITIALIZATION
At power-on, the printhead is moved slowly left until the carriage reaches the left margin.
This is accomplished when a small tab on the carriage engages a photosensor mounted on
the left endplate. This position is referred to as the true left margin and all future printhead
motion is referenced to this point. Features and forms status which were present in the
printer when power was last switched off are loaded from the nonvolatile memory into
working storage. Therefore, the printer should power-on in exactly the same configuration
it was in when last used.
1.4: PRINTHEAD ASSEMBLY
The printhead consists of a frame, solenoids, tungsten printwires and a printhead nose. The
solenoids are housed in the frame in a radial symmetrical arrangement. Each solenoid
drives one printwire. The printwires extend from the solenoids through the printhead nose
and are partially exposed at the tip of the printhead nose. The printhead nose houses guides
which orient the printwires so they form a vertical column at the tip of the printhead nose.
Heat generated by the solenoids during operation is dissipated through a heatsink which is
mounted to the printhead frame. The printhead assembly is mounted on the carriage which
correctly positions the printhead as the solenoids drive the printwires in order to form
characters. A printwire is fired when 55 VDC is applied to a solenoid. Power from a
modulated pulse-width power amplifier is supplied to the printhead solenoids via a ribbon
cable.
1.5: PAPER FEEDING
The printer is designed to accommodate forms ranging in width from 3 to 15 inches. Forms
must be of the pin-feed type with a hole spacing along the edge of 0.5 inch, and a diameter
ranging from 0.150 to 0.160 inch. Multiple forms of up to six sheets may be used, with a
maximum recommended thickness of 0.022 inch. If a form with card stock is used, the
card must be the last part, and entry into the printer should be through the bottom-feed slot.
The printhead-platen gap adjustment lever should be moved to its full back-position before
loading forms (i.e. maximum gap). It may be moved inward (toward the platen) when
printing commences until the ink starts to smudge, then back one detent. A pair of forms
tractors engage the feed holes of the paper to move it through the printer. Flat sheet metal
plates guide the paper, and a mylar tensioner maintains a slight drag for a flat, wrinkle-free
print surface. The drive tractor may be adjusted horizontally to accommodate forms of
different widths. The tractors are driven by a square shaft through a rubber timing belt
linked to a stepper motor. Front panel keys are available for paper-advance and vernier
alignment.
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