HP 750 - Manual (Page 48)

5-6 Functional Overview C4705-90000
MediaĆAxis Mechanism
The media (XĆaxis) motor is mounted under the right endcover and is electrically connected
to the main PCA, which contains the mediaĆmotor driver. It has a wormĆstyle pinion gear,
which meshes with a gear at the right end ofthe drive roller. When the media motor rotates,
it moves the drive roller and, consequently, the media. The encoder mounted on the motor
sends feedback about the media motor position to the main PCA.
In DesignJets 700, 750C Plus and 755CM the media motor has a zero position which is
indicated to the main PCA via the encoder.
Primer Stepper Motor
The primer stepper motor is mounted on the plotter's left sideĆplate and connects to the main
PCA through the serviceĆstation cable. It is controlled by the servo processor on the main
PCA and is used to drive the nozzle primer.
Bail Stepper Motor
The bail stepper motor is mounted on the plotter's left sideĆplate and connects to the main
PCA through the serviceĆstation cable. It is controlled by the servo processor on the main
PCA and is used to drive the bail.
Wiper Stepper Motor
The wiper stepper motor is mounted on the service station and connects to the main PCA
through the serviceĆstation cable. It is controlled by the servo processor on the main PCA
and is used to drive the orthogonal wiper.
Fan
An internal cooling fan is supplied with +12 V. It is switched ON and OFF by the servo
processor and is mounted in the electronics enclosure at the rear ofthe plotter. The fan is
primarily used to cool the power supply PCA and the main PCA when plotting.
Window Sensor
The window sensor is a mechanical switch mounted on the right sideĆplate at its top front
edge. Feedback about the window's position (up or down) is sent to the main PCA through
the front panel.
PinchĆWheel Sensor
An optical pinchĆwheel sensor is mounted on the lower rear portion ofthe plotter's right
sideĆplate and is electrically connected to the main PCA. When the pinch arms are raised, a
cam in the pinchĆarm lift mechanism interrupts the beam of the optical sensor, and, when the
pinchĆarms are lowered, the beam path is cleared. Thus, the position ofthe pinchĆwheel can
be determined from the electrical state of the sensor.