Orion 7831 User Manual

Orion® TrueTrack Single-Axis DC Motor Drive System

#7831

Thank you for your purchase of an Orion TrueTrack motor drive system. The TrueTrack allows convenient

hands-free sidereal tracking of the night sky for SkyView Pro mounted telescopes. The motor drive sys­tem features a push button hand controller that can move the telescope along the right ascension (R.A.)
axis at speeds 2x and 8x the sidereal rate. This provides an easy way to center objects in the eyepiece.
The TrueTrack single-axis drive is also a useful component for doing short and medium-exposure astro­photography. The electronic hand controller allows positional corrections to be made in the right ascension
(R.A.) during an astrophotographic exposure.

Attaching the R.A. Motor

Figure 1. The R.A. motor cover.

R.A. motor

cover

Phillips-head

screw

Drive

Remove the telescope tube, counterweight, and counter­weight shaft from the mount before attaching the motor drive.

1. Remove the R.A. motor cover from the mount by loosening
the Phillips head screw on the bottom of the cover (Figure

1). Slide the cover off the mount.

2. The R.A. motor assembly (Figure 2) is attached to the
mount by a socket-head cap screw that goes through the
hole in the rear of the equatorial mount, just above the rear
latitude adjustment L-bolt (Figure 3). Attach the 4mm screw
to the end of a 4mm hex key and push it up through the
hole in the rear of the equatorial mount. Hold the R.A. drive
in your hand so that its threaded hole meets up with the
screw as it comes out the other end of the hole. Thread the
screw into the threaded hole of the R.A. motor assembly
until secure, but do not overtighten. This attachment pro­cess is tricky, and it may take you several tries before you
get it right.

3. Remove the R.A. slow-motion control knob from the R.A.
worm gear shaft if it is on the side of the mount that the

Modular
jack

Parts List

1 R.A. motor assembly

1 Manual clutch assembly (brass gears)

1 Hand controller

1 Battery pack

1 4mm socket-head cap screw

2 Velcro strips (1“hook” strip, 1 “loop” strip)

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Brass gear

Threaded hole

Figure 2. The R.A. motor assembly.

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IN 196 Rev. B 03/09

R.A. worm gear
shaft

Brass gear of R.A.
motor assembly

Figure 3. The motor is attached to the front of the mount by a

socket head cap screw pushed up through the hole in the rear of the
mount.

motor assembly’s brass gear is on, and attach it to the
opposite end of the worm gear shaft.

4. Slide the open end of the manual clutch assembly (Figure

4) onto the wormgear shaft. Rotate the manual clutch
assembly so that the setscrew will press against the flat on
the R.A. worm gear shaft. Secure the manual clutch
assembly by tightening the setscrew with a 2mm Allen
wrench.

Brass gear

Thumbwheel

Setscrew

Open end

Hole

Figure 5. The assembled R.A. motor drive.

Using the Velcro

Two strips of velcro (one strip of “hooks” and one strip of
“loops”) have been provided so you can create a place to keep
the hand controller out of the way when not in use. Place the
“hook” strip of velcro on the back of the hand controller and
the“ loops” strip on a tripod leg or on the mount where it will be
in a conveniently reached spot. Simply hang the hand control­ler by the velcro when it is not in use. Make certain when you
attach the velcro that the hand controller will not interfere with
the motion of the mount.

Operating the Single-Axis

Figure 4. The manual clutch assembly.

5. Make certain that the teeth of the motor assembly gear
mesh with the teeth of the manual clutch assembly gear.
Also, make certain the gears are not too tightly pressed
together. You can adjust the way the gears mesh by tight­ening or loosening the socket-head cap screw that is used
to attach the R.A. motor assembly to the mount. If the
gears are not meshed correctly or are too tightly pressed
together, then the drive will not track properly, or at all.

When finished, the assembled R.A. drive should resemble
Figure 5. You can now replace the R.A. motor cover and secure
it with the Phillips head screw.

Please note that if you wish to use the slow-motion con­trol knob to move the telescope in R.A. with the R.A. motor
drive attached, you must first loosen the thumbwheel on
the manual clutch assembly. Failure to do so may result
in damage to the motor.

Drives

For the motor drive system to track properly, the equatorial
mount must be polar aligned. This involves aligning the R.A.
axis of the mount so it is parallel to the Earth’s axis of rotation
(polar axis). Consult the manual that came with your SkyView
Pro equatorial mount for details on how to polar align it.

The telescope must also be precisely balanced for the motor
drive system to properly track the night sky. Consult the man­ual that came with your mount for details on balancing your
telescope on the R.A. and Dec axes.

Insert four D-cell batteries into the battery pack. Orient the
batteries as indicated on the white plastic battery holder.
Connect the end of the battery pack’s power cord to the DC
power input on the hand controller.

A cord is permanently connected to the hand controller; con­nect the modular plug on the end of the cord to the modular
jack on the R.A. motor assembly through the hole in the bot­tom of the R.A. motor assembly cover.

When observing in the Northern Hemisphere, the N/S switch
on the hand controller should be set in the “N” position. For the
Southern Hemisphere, it should be in the “S” position.

Make sure the thumbwheel on the manual clutch assembly is
engaged (i.e. tightened against the brass gear), and turn the

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