Radio Shack TRS-80 Service Manual page 47

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• Pen down $(ate
The pen descends when a current flows through the eJectromagnet for 5 ms in a direction opposite that which is i.1npressed
during suction against the suction force of the pcnnancnt magnet. After Sms, the pen-down state will be n1aintained by the
acluator spring force.
5, Color Change Mechanism Section
The color change mechanisn1 section consists of the X-direction dri\'e 1nechanisn1, a pen holder and holder stopper, both in the
slider unit , and projections inside the holding plates. The ope rating principles are explained below.
Holder StoPP'(tr
'
....
Pen Holder
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J
I
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Side Pltte
(Left)
I
I
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Figure 5
1-.f
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Figure 6
First, the slider
n1oves
to
t~te
area a-I jn Figure 6 (45 pulses to the left from the origin). Then, tlte holder stopper in the slider
contacts the projection on. the holding plat e, and the wedge sec tion of the holder stopper slips out of the pen holder, and
releases holder to rotate. Next, by repeating the movement of the X motor for 30 pulses each in direction A and to the left,
the pen
(j)
in Figure
5
clnanges to pen
@ .
The spring moves the pen holder to the right until it returns to the origin. The pen
holder then enters its groove, and printer is ready to pri.nt.
6. Pen Ejection Mechanism
The pen ejection mechanism consists only of the pen ejection lever that is mounted on the side plate (right). The slider un. i t is
moved
fully
to the side plate (right) and stops. Push the peo ejection lever towards you. and the pen will ejec t.
Pen E jection Lever.
Slider Unit
figure 7
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