TM 5-6675-323-14
Pen solenoid. Controls the up/down position of each pen. The controlling
b.
s i g n a l to the pen solenoid may originate from either PCA A3 or PCA A5. The pen up
o r pen down signal from either the processor or the front panel is coupled through
connector J5-7 to the base of input transistor Q17. A low (O V) pen down signal
turns transistor Q17 causing a positive input to the inverting input of current
a m p l i f i e r U 3 - 2 . T h e negative output of U3-6 turns on transistors Q18 and Q19 via
diode CR4.
C o n d u c t i o n of Q18 provides a current path from the -12 V supply through
c o n n e c t o r s J1 and J2, pin 8, to energize the pen solenoid which is mounted on the
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plotter arm.
From there, the current travels through the pen solenoid to connectors
J1 and J2, pin 7, and then through transistor Q18 to common. Diode CR4 provides
protection for transistors Q18 and Q19 when the pen is up. A positive pen up signal
keeps transistors Q17 and Q18 in a nonconducting state, so the pen solenoid is not
energized and the pen remains in an up position.
c . Transistor driver PCA Card A12. Boosts an analog position signal from
interpolator to drive the X- and Y-drive motors. The analog position signal is
interfaced by X14 drive amplifiers.
P C A A12 is mounted adjacent to the stepping
motors on the underside of the upper deck assembly and houses the eight motor drive
power transistors. These eight motor drive power transistors provide current to the
X- and Y-drive motor windings, utilizing the +26 V supply from the pen relay drive
circuits.
T h e eight transistors are in pairs, one NPN and one PNP, so each of the
four motor phase windings has two transistors connected in a push-pull arrangement
to provide its drive current.
d. X- and Y-axis drive motors.
D r i v e and control the movement of the plotter
arm and thus, the chart pen. The operation of both X- and Y-motors is identical.
I f the X-sine phase winding is activated, then PCA A8 outputs a signal through
connector J1-6 which is coupled through connector J1-2 to common the bases of tran-
s i s t o r s Q5 and Q6.
If the state of input signal is positive, transistor Q6 will
conduct, energizing that motor winding which is in common with the emitter circuit.
If the input signal is negative, then transistor Q5 will conduct, energizing the
m o t o r w i n d i n g i n a r e v e r s e d i r e c t i o n . T h e stepping X- and Y-drive motors are iden-
tical.
E a c h has 1.8-degree steps making 200 steps per 360-degree rotation. Motor
rotation is translated into movement of plotter arm through the drive wire system.
Provides an electrostatic chart hold voltage and dc
3 - 3 . 2 . 6 P o w e r SU p p lY .
s u p p l y voltages as shown below:
For power supply control only: +8 V, +5 V, +12 V
For plotter circuitry: +7 V, +5 V, +12 V, -12 V, +26 V, -26 V
The power supply consists of the following PCA cards:
Main power PCA card A9
Control PCA card A10
P o w e r distribution PCA card A11
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