Mechanical Theory 1_1; Print Head Mechanism And Operation - Atari 1025 Field Service Manual

SECTION
ONE
THEORY
OF OPERATION
INTRODUCTION
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^
The
ATARI
1025
1
Printer
is
a desk
top,
receive
only, serial .impact dot matrix
printer.
The
1025
Printer
connects
directly to the
ATARI
computer
or disk drive with
an I/O cable and receives
its
instructions thereby.
It is
a
uni-directional
printer.
MECHANICAL THEORY
PRINT
HEAD MECHANISM AND
OPERATION
PRINT
HEAD MECHANISM
The
print
head
consists of the
following:
•
Wire Guide
•
Yoke
•
Armature Assembly
•
Spacer
•
Magnet Assembly
The
print
head
is
spring-loaded and
contains a
permanent
magnet.
It
can be
easily
removed
and
installed.
It's
mounted
on the carriage that runs
parallel to the platen
and
is
attached
to
the
PCB
at connector
CN3.
PRINT
HEAD OPERATION
When
not operating, the armature
is
attracted by the permanent magnet
(see
Figure
1-1).
The
print wire,
which
is
fixed to the armature,
is
held retracted within the wire
guide.
When
a character
to
be printed
is
detected by
the control
circuit,
a current
flows
to the
coil
corresponding
to that
print wire.
When
the
coil
is
energized, the
magnetic
flux generated by
the
permanent magnet
is
nullified.
The
print wire
is
then
driven
toward
the platen by force
of the armature
spring.
Thus
a dot
is
printed on the
paper.
After
printing the character, the
magnetic
flux of the
permanent magnet
attracts the
armature
again
so the
print
wire
is
retracted
into
the wire guide.
Atari 1025 Printer
Ffeid
Service
Manual
1-1