Paper Motion - Radio Shack TRS-80 Service Manual

2.7
PAPER MOTION
(Figure 2-6)
There
are
two methods
of
moving paper through the
printer:
1)
manually, by pushing
in
and
rotating
the platen
knob
in a
clockwise direction
and
2)
remotely, by
a
decoded
line
feed function,
which causes the paper to
move
one
line.
The decoded
line
feed function causes the paper to
advance by
activating the paper
movement
solenoid
in
the
line
feed clutch
unit.
When
energized, the solenoid allows the
line
feed clutch unit
to rotate, driving
the platen
and
paper feed
mechanism.
For
each
single line
feed operation, the solenoid
is
energized
1 1
milliseconds.
2.7.1
LINE
FEED/CARRIAGE
RETURN
A
line
feed/carriage return
is
generated
by
the following conditions:
1.
Receiving
a line
feed/carriage return
code
(decimal
10 or
13).
2.
The
auto
line
feed function
is
enabled
when
a
jumper
wire
is
installed
between E1 and
E2
on
the electronics board.
To
dis-
able the
auto
line
feed function,
a
jumper
wire
is
installed
between E
1
and
E3.
During
a line
feed/carriage return operation, the
line
feed solenoid
is
activated
via
the
power
driver
(PMSOL(N)).
Also the
printer goes
BUSY
and cannot
receive
any input data
for
the duration of the
line
feed/carriage return operation.
NOTE
FOR THE
26-1150
LINE PRINTER,
SEE
FIGURE
3-1
AND
ITS
NOTE.
INPUT DEVICE
INPUT
CONTROL
LOGIC
PSSOL
-O-t?] 4IHI}
HI
l
CI
P
(NOTE
I)
I
NOTE
I:
CIP WILL NOT CAUSE PMSOL
IF
CUT
AUTO
LINE FEED OPTION
IS
INSTALLED
Figure 2-6.
PAPER
MOTION
2-6