Radio Shack TRS-80 PT-210 Service Manual page 12

@
LF motor assembly
The LF motor controls the feeding of the thermosensitive paper.
Figure
8.
The motion of the LF motor is transmitted to the motor timing pulley
(4)
set on the platen shaft
(3)
through the motor timing pulley @and the LF timing belt
(2)
and is further transmitted to the platen
(5)
The thermosensitive paper is led in by the friction force of the platen@ and then is fed by the ro-
tation of the platen
(5)
as pressure is applied to the paper by pinch rollers.
The LF motor feeds paper in the direction of Y-axis by a distance of 1 line; that is, it moves 4.23 mm
(1/6") after 6 pulses of the LF motor control signal. The thermal head is not in contact with the ther-
mosensitive paper during line feed, due to the operation of a relief solenoid.
Solenoid assembly
The solenoid assembly controls printing motions by causing the thermal head to make contact with
thermosensitive paper and to make a relief from the paper.
When a control signal i s input t o the solenoid, the solenoid is actuated and a rotary motion is trans-
mitted to the head shaft
(3)
through the head lever
(2)
which is coupled with the plunger
@
The
underhead
(4)
is coupled to the head shaft
(3\
and the thermal head assembly
@
is set to the under-
head.