ASTRO-PHYSICS Mach1GTO User manual

1
ASTRO-PHYSICS
Mach1GTO GERMAN EQUATORIAL WITH
GTOCP3 SERVO MOTOR DRIVE
MACH1GTO PARTS LIST 3
FEATURES AND SPECIFICATIONS 4
INTRODUCTION 5
Why Polar Alignment is Important 5
ASSEMBLY INSTRUCTIONS 6
Before You Leave Home 7
Assembling and Disassembling the Two Axes 7
Gross Latitude Adjustment 7
Assemble Pier or Tripod 7
Portable Pier 7
Adjustable Wood Tripod (AWT000) 8
Adjustable Aluminum Tripod (SDS400) 8
6” Eagle Adjustable Folding Pier 8
Tripod Adapter 8
Attach the Mount to the Pier Post or Tripod 8
Altitude and Azimuth Adjustments - Rough polar alignment 9
Attach Mounting Plate 12
Assemble Counterweight Shaft 13
Optional 10.7” x 1.875” Counterweight Shaft 14
Attach Mounting Rings (purchased separately) 14
Fine Polar Alignment 14
Methods for fine polar alignment 15
Altitude and Azimuth Adjustments 15
CLUTCH KNOBS AND BALANCING 16
R.A. and Dec. Clutch Knobs 16
Balancing Your Telescope 16
First, Balance the Declination Axis. 16
Second, Balance the Polar Axis 17
CABLE MANAGEMENT 17
Introduction to one of the Mach1GTO’s most Innovative Features 17
Preparation 17
Cable Installation – the First Time 18
Disassembly and Subsequent Setups and Polar Alignments 19
A Note on the Mount’s Servo “Y” Cable 19
A Few More Hints and Tricks 19
SERVO MOTOR DRIVE 21
GTO Control Box – GTOCP3 21
R.A. and Dec. Cable Connections 22
12V Connector 22
POWER Indicator Light 22

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KEYPAD Connector 22
RS-232 Connectors 22
FOCUS Connector 23
RETICLE Connector 23
AUTOGUIDER Connector 23
+6V Connector 23
N and S Switch 23
Drainage Holes 23
GTO KEYPAD CONTROLLER OPERATION 24
SLEWING YOUR MOUNT IN BELOW FREEZING TEMPERATURES 24
MOUNT CARE,CLEANING AND MAINTENANCE 24
Care 24
Cleaning and Touch-up 25
Mount Maintenance 25
ADDITIONAL TIPS AND SUPPORT 25
TROUBLESHOOTING 25
RECOMMENDED READING FROM OUR STAFF: 28
CHARACTERIZING THE DEC AXIS MOTIONS 29
ASTRO-PHYSICS MOUNTING PLATE FASTENER CHART 30
PLEASE RECORD THE FOLLOWING INFORMATION FOR FUTURE REFERENCE
MOUNT SERIAL NUMBER: ______________________________
KEYPAD SERIAL NUMBER: ______________________________
GTOCP3 SERIAL NUMBER: ______________________________
PURCHASE DATE: ______________________________

3
ASTRO-PHYSICS
Mach1GTO GERMAN EQUATORIAL WITH
GTOCP3 SERVO MOTOR DRIVE
MACH1GTO PARTS LIST
1 Mach1GTO German Equatorial Head with Servo Drive Motors
1 Stainless counterweight shaft with washer stop and black plastic knob (knob has 1/4” thread)
1 GTO Control Box (Model GTOCP3) with pouch and control box-to-pier adapter (CBAPT)
1 Y cable – R.A. portion is 24.5” long and Dec portion is 40.5” long
1 D.C. power cord (cigarette lighter adapter on one end) - 8’ long
1 GTO Keypad controller with 15’ coiled cable and Instruction Manual
1 PulseGuide™ by Sirius Imaging – remote control utility for Windows™ PC’s (CD-ROM)
1 Hex key set
In order to assemble your mount fully, you will need the following items sold separately:
•Telescope mounting plate – many choices to fit your telescope and observing needs. See detailed section later
in this manual.
•Pier or Tripod
o6” Eagle Adjustable Folding Pier (EAGLE6)
oAstro-Physics 6” Portable Pier – 6 sizes from 24” to 62” tall (6X##PP)
oAdjustable Wood Tripod (AWT000)
oAdjustable Aluminum Tripod (SDS400) This tripod can be used, but is not recommended for heavier
loads.
oAdapt to your own custom pier or tripod with our Tripod Adapter (ADATRI)
•Counterweights – 6 lb. (6SLCWT) and 9 lb. (9SLCWT) are available. (5 lb., 10 lb. and 18 lb. with optional
counterweight shaft – see below.)
•Portable rechargeable 12 volt battery pack or a power converter to convert your household AC current to DC
current of 12 – 16 volts at a minimum of 5 amps. We offer a 13.8 volt 5 amp converter (PS138V5A) and a 15
volt 10 amp converter (PS15V10A).
Many of these items will be discussed throughout these instructions. Several additional options are available:
•Optional 10.7” total length x 1.875” diameter Counterweight Shaft (M1053) and Safety Stop (M12676) for use
with 5 lb. (5SCWT), 10 lb. (10SCWT) and 18 lb. (18SCWT) counterweights. Handy for travel or if you already
own a 900 or 1200 series mount.
•Polar Alignment Scope with Illuminator (PASILL4) – for quick and easy polar alignment
•Pier accessory trays: A flat accessory tray with raised sides, a tray with eyepiece holes, a control box adapter
bracket and two support bar options are now available to fit the 6” Eagle Adjustable Folding Pier, some sizes of
the 6” Portable Pier and both tripods. They are handy and attractive places to keep your eyepieces and other
astro-gadgets close at hand! The Control Box Adapter is included in mounts shipped starting in April, 2007.
•Santa Barbara Instrument Group CCD Imaging cameras, STV, ST-4 Autoguider or other imaging camera- if you
plan to pursue CCD imaging or astrophotography
•PEMPro™ (Periodic Error Management Professional) is a Windows software application that makes it easy to
characterize and reduce periodic error. PEMPro™ will analyze the performance of any mount that is equipped
with a CCD camera and compatible camera control software. PEMPro™ gives you powerful tools to program
your mount's periodic error correction firmware to achieve the best possible performance for your mount.
PEMPro™ dramatically improves guided and unguided imaging resulting in better images and fewer lost
exposures. While the periodic error of your Mach1GTO will be 7 arc seconds or less, you can reduce it even
further to maximize performance without auto-guiding.
Note on Encoders: Mounted encoders can not be used with the Mach1GTO They are not needed since the go-to
functions of the mount are so much more accurate. The encoder that is built into the servo motor itself has a resolution of
0.05 arc seconds vs. 324 arc seconds for mounted encoders.
For a complete catalog of our Mach1GTO accessories, visit our website – www.astro-physics.com

FEATURES AND SPECIFICATIONS
for mounts shipped starting in April, 2007, beginning with Ser. # M10053
R.A. worm wheel: 5.9”, (150 mm) 225 tooth aluminum
Dec. worm wheel: 5.9”, (150 mm) 225 tooth aluminum
Worm gear: Brass, 0.709” (18 mm) diameter
R.A. shaft: 2.36”, (60 mm) diameter
R.A. Bearings 3.1”, (78 mm) diameter
R.A. thrust surface: 4.1”, (104 mm) diameter
Dec. shaft: 2.36”, (60 mm) diameter
Dec. Bearings 3.1”, (78 mm) diameter
Dec. thrust surface: 4.1”, (104 mm) diameter
Periodic Error 7 arc seconds, peak-to-peak, (+/- 3.5 arc sec) or less guaranteed
Counterweight shaft: 14.5”, (368 mm) overall, 13.6”, (345 mm) useable length, 1.125”, (29 mm) diameter,
stainless steel, removable with knob and safety washer
Optional Counterweight Shaft 10.7”, (272 mm) overall, 9.625”, (244 mm) useable length, 1.875”, (48 mm) diameter,
stainless steel, removable – requires One-piece Washerless Safety Stop (M12676).
Stores inside declination axis for travel and uses same weights as 900 and 1200
series mounts.
Latitude range: 0 to 70 degrees with or without polar scope attached.
Azimuth adjustment: Approximately 25 degrees (+/- 12.5 deg. from center)
Motors: Zero-cogging servo motors
Power Consumption: 0.4 amps at the sidereal rate
2 amps both motors slewing
Power requirements: 12 VDC, range 11.5 to 16
Weight of mount: Total of Equatorial Head -28.5 lbs. (13.0 kg)
Dec axis - 11.5 lbs. (5.2 kg)
R.A axis - 16.0 lbs. (7.3 kg)
Pier Adapter – 1 lb. (0.5 kg)
Counterweight shaft with washer and knob - 4.1 lbs. (1.9 kg)
Optional 10.7” x 1.875” Counterweight Shaft with Safety Stop – 7.7 lbs. (3.5 kg)
Capacity of Mount: Approximately 45 lbs. (20kg) - telescope and accessories (not including
counterweights), depending on length. Will accommodate Astro-Physics and similar
refractors up to 160mm f7.5, 8” - 11" SCT or 6” – 8” Mak Cas. These are only
guidelines. Some telescopes are long for their weight or very heavy for their size and
will require a larger mount. Note: As weight of scope and accessories increases,
proper balancing becomes more critical. See section on balancing for more
information.
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INTRODUCTION
The Astro-Physics Mach1GTO - Observatory Performance in a Small Package! This is the first, compact, light-weight
mounting that was designed for utmost portability while maintaining extreme rigidity and excellent tracking accuracy. No
shortcuts were taken to achieve these goals. From the highly accurate fine-pitch gearbox to the precision machine tool
bearings, to the innovative worm wheel and clutch design, this mount represents a new approach to this vital part of the
overall imaging train.
The advent of modern CCD cameras and telescopes with high-resolution optics has placed greater demands on the ability of
mountings to do their part to achieve precision tracking and guiding. At the same time, the mounting should be easy to use
with adjustments and setups that are straight-forward and accurate. We have done everything possible to eliminate the
frustrations and limitations inherent in a lesser mounting and so put the fun back into the hobby of amateur astronomy.
The DC servo motor drive with GTO computer system, the keypad with its digital display screen, and the included
PulseGuide™ software all combine to offer extraordinary sophistication for today’s observer. Whether you enjoy visual
astronomy exclusively or plan an aggressive astrophotography or CCD imaging program, this mount will allow you to
maximize your night out under the stars.
The advanced keypad features allow you to slew automatically to objects in a wide range of databases, as well as any
R.A./Dec coordinate. A large selection of common names for stars and other objects makes your selection a snap. The rapid
slew rate of 5 degrees per second (1200x) allows you to locate objects very quickly and accurately. You will be very pleased
with the intuitive operation of this keypad. There are no complicated sequences of keystrokes to remember. It is so easy to
use that even if you don’t use it for a few months, you will feel at home with the keypad very quickly.
PulseGuide™ is a stand-alone Windows (98, ME, 2000, NT4, XP) utility that provides complete remote control of all Astro-
Physics GTO mounts. It derives its name from its most distinctive feature, pulse guiding, which can improve unguided
tracking. Specifically, it can help correct tracking errors caused by polar misalignment and atmospheric refraction. You can
also train PulseGuide™ to track objects moving relative to the stars, such as asteroids, comets, and the moon. In addition to
pulse guiding, PulseGuide™ also has many useful utility features. PulseGuide™ was written by Ray Gralak of Sirius-
Imaging. Please refer to his website http://www.pulseguide.com for further developments and enhancements.
The Mach1GTO has the strength, rigidity and sophistication to tempt you to permanently place it in a state-of-the-art
observatory. However, its portability and ease of setup make it the finest mount of its size for remote use in your favorite
dark sky location and even for travel to exotic observing locations around the world. This is the perfect mount for a small to
mid-size refractor, Newtonian, Cassegrain or astrograph.
In order to maximize your pleasure on your first night out,
we recommend that you familiarize yourself with the
assembly and basic operation of the mount indoors. The
temperature will be comfortable, the mosquitoes at bay,
and you'll have enough light to see the illustrations and
read the manual. Please take particular note of counter-
balancing, use of the clutches and operation of the
keypad controller.
Why Polar Alignment is Important
Polar alignment compensates for the Earth’s rotation.
If you were to take a long exposure photograph with
Polaris (often called the North Star) in the center of the
field, you would discover that all stars seem to revolve
around Polaris. This effect is due to the rotation of the
earth on its axis. Motor driven equatorial mounts were
designed to compensate for the earth's rotation by
moving the telescope at the same rate and opposite to
the earth's rotation. When the polar axis of the telescope
is pointed at the celestial pole (polar aligned) as shown
in the diagram, the mount will follow (track) the motions
of the sun, moon, planets and stars. As a result, the
object that you are observing will appear motionless as
you observe through the eyepiece or take astrophotos.
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ASSEMBLY INSTRUCTIONS
Please read all instructions before attempting to set up your Mach1GTO mount. The Mach1GTO is very rugged, however like
any precision instrument, it can be damaged by improper use and handling. Please refer to the following illustrations. The parts
are labeled so that we can establish common terminology. Throughout the text, SMALLCAPS are used to refer to parts that are
illustrated on this diagram.
NOTE: The following terms and abbreviations are used interchangeably in these instructions:
polar axis = right ascension axis = R.A. axis = R.A. housing
declination axis = dec. axis = dec. housing
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Before You Leave Home
Since most of us must set up our instruments in the dark, in the cold or while battling mosquitoes, a bit of preplanning and
organization is important. There are few simple things that can be accomplished in the comfort of your home before heading
outside. We would advise anyone to do a complete practice run from start to finish before venturing out into the field. This
is especially important for those of you who may be new to German Equatorial Mounts.
Assembling and Disassembling the Two Axes
Because of its compact size and light weight, the Mach1GTO does
not need to be disassembled for normal transport to and from an
observing site. There will rarely be a need to disassemble the two
axes. However, those of you who do disassemble your Mach1GTO
for transport will need to be familiar with how the two axes are
assembled and disassembled. When re-assembling your mount,
we recommend that you fasten the RA axis onto your pier or tripod
first. That way, you have a solid platform firmly holding on to your
RA axis while you bolt the declination axis in place. The pier
becomes your “extra set of hands.”
The two axes assemble quite easily with the four 1/4-20X1” SOCKET
HEAD CAP SCREWS shown in the Assembly Diagram on page 6. To
properly line up the two axes, the RA axis must be positioned with
the two pairs of screw holes on the east (2) and west (2) rather than
on the north and south. In addition, the CLUTCH KNOBS of the RA
axis should be at 10 o’clock, 2 o’clock and 6 o’clock. The four bolt
holes will not line up in any other position. To turn the RA axis to
this position, loosen the three CLUTCH KNOBS and turn the axis.
When in the proper position, retighten the CLUTCH KNOBS for safety.
The declination axis is placed into its position in the RA axis with the COUNTERWEIGHT ADAPTER down, and the DECLINATION
HUB PLATE up as in the Assembly Diagram. Unlike the bigger 900GTO and 1200GTO mounts, the dec axis of the
Mach1GTO must be straight and square to the RA mating surface when mounted. Don’t try to tilt it into place as you would
with the larger dovetailed mounts. Keep a hand on the declination axis to keep it from falling off until you have at least one
of the screws loosely fastened. With the declination axis in place, insert and tighten the four 1/4-20 X1” SOCKET HEAD CAP
SCREWS.
Gross Latitude Adjustment
Unlike its bigger brothers, the 900GTO and 1200GTO, the Mach1GTO does not have latitude ranges that should be preset
before venturing out into the field. However, you may still wish to give yourself a head start before heading out into the dark.
Each side of the Mach1GTO’s POLAR FORK BASE is clearly marked with a LATITUDE SCALE. You can preset the mount to
your latitude before leaving the house, if you wish.
Assemble Pier or Tripod
(purchased separately)
Please note: Starting in 2008, the Mach1GTO has six attachment
holes in its base to better facilitate the different pier tops. Older
mounts having three attachment holes may be limited in terms of the
tripod or pier leg orientations that can be chosen. Only three of the
holes get used.
Portable Pier
Begin by assembling the portable pier at the desired observing
location. With six attachment holes in the Mach1GTO’s base, you can
now orient the pier with a leg to the north or south as you prefer.
1. Slide the three legs onto the nubs of the base and rotate the
assembly so that one of the legs points toward the north or
south. You can use either orientation in either hemisphere.
Most people prefer to have one leg point toward the pole.
2. Place the pier post on the base orienting the three eyebolts directly above the legs.
3. Attach the tension rods. The turnbuckles should be drawn tight until the whole assembly is stiff enough to support
your weight without movement.
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Adjustable Wood Tripod (AWT000)
Open the legs of the tripod at the desired observing location. Note which direction is
north (south if you are below the equator).
1. Position the tripod with one of the legs pointing roughly toward or away from
your pole.
2. Attach the shelf to each of the three legs with the knobs provided.
3. Adjust legs to the desired height and spread them fully.
4. Lock in position with the hand knobs and make sure that leg clamps are tight.
Note: Your tripod must be equipped with the Tripod Adapter (ADATRI) to mount the
Mach1GTO. If you purchased your tripod from Astro-Physics, it came with this adapter
already installed.
Adjustable Aluminum Tripod (SDS400)
Loosen the clamp on the support and spread the legs to the desired
position. Extend the legs to the desired height and clamp everything
tightly. Point one of the legs toward the north (or south) pole.
Note: The Adjustable Aluminum Tripod is not suitable for the heavier loads that the Mach1GTO can
carry. It is usable for setups with total instrument weight of less than 20 lbs. or if portability is of critical
importance. Also, see the note above regarding the Tripod Adapter (ADATRI).
6” Eagle Adjustable Folding Pier
Assembly instructions for the 6” Eagle Adjustable Folding
Pier are included with the pier. Please refer to those
instructions for assembly, adjustment and leveling
procedures. Your Mach1GTO will fit into the 6” Eagle
Adjustable Folding Pier without any additional adapters.
Simply set the mount into the open top of the pier and attach
with the three PIER ADAPTER KNOBS included with the mount.
Tripod Adapter
If you have your own custom pier or tripod with a flat surface on top, you can use our
Tripod Adapter (ADATRI) for mounting the Mach1GTO. We also offer a separate
adapter that can be used in conjunction with this Tripod Adapter to attach to a
Losmandy Heavy Duty Tripod or a Losmandy Meade Tripod Adapter (LT2APM).
See the website for details.
Attach the Mount to the Pier Post or Tripod
The PIER ADAPTER is already attached to your Mach1GTO. Starting in 2008, there are six attachment holes in the PIER
ADAPTER base for positioning flexibility. You, of course, only use three of them (every 120°) with the three provided PIER
ADAPTER KNOBS. Remove the three PIER ADAPTER KNOBS from the PIER ADAPTER. Simply set the mount into the pier post on
your 6” Eagle Adjustable Folding Pier, your Astro-Physics Portable Pier, or the adapter of your Adjustable Wood Tripod.
Fasten with the three PIER ADAPTER KNOBS. If you are attaching the Control Box Adapter or a Tray Support Bar at the top of
your pier or tripod, do that now. (Note: photo on next page is of an earlier vintage with three pier attachment holes.)
8

Altitude and Azimuth Adjustments - Rough polar alignment
For rough polar alignment, your goal is to sight the
celestial pole when looking through the polar
alignment sight hole in the center of the polar axis.
You will need to make altitude (up/down) and
azimuth (side-to-side) adjustments to the position
of the mount. Before beginning, make sure that
the mount is pointing roughly north using the built-
in compass and that your pier or tripod is level
using the mount’s built-in bubble level.
Remember that magnetic north is not the same as
true north and varies both with time and with your
location. In the fall of 2006, on the northeast tip of
Maine, for example, magnetic north is west of true
north by a whopping 18 1/2 degrees! On Mauna
Kea in Hawaii, by contrast, magnetic north is
about 9 1/2 degrees east of true north. Observers
along the Mississippi River are lucky and are
nearly dead on. These values change by several
minutes every year. With experience at a
particular site, however, you will soon learn to use
the compass to find true north. (You will know just
how far off magnetic north is for your location.) In
addition, there is a website funded by our U.S. tax
dollars that will compute the declination of
magnetic north relative to true north for any
location that you input. The link is as follows:
http://www.ngdc.noaa.gov/seg/geomag/jsp/Declin
ation.jsp
Note: It is possible to achieve perfect polar
alignment without having the pier level, but it is
more difficult. With a pier that is not level, each
adjustment in azimuth also causes a minor shift in
altitude and vice versa. This is why we have
included the bubble level on the Mach1GTO.
Keep in mind that unless you are a serious
astrophotographer or imager, “perfect” polar
alignment is not critical.
We recommend that you do your rough polar
alignment with the mount only since you will be
making major adjustments to the position of the mount at this time. The remainder of the equipment: telescope, finder,
camera or eyepiece and counterweights will add considerable weight and require more hand effort to make the adjustments.
Later, you will do your final polar alignment with the telescope and counterweights attached, but the adjustments will be
small.
Note: The illustrations below show only the RA axis. This was done for clarity since the declination axis blocks the view into
the POLAR FORK BASE. You will, of course, be doing your rough alignment with the mount assembled.
1. If the Polar Scope (PASILL4 or earlier model) is installed, you may remove it to complete these steps.
2. Remove the POLAR SCOPE CAP (unless a polar scope was installed). If you examine the polar axis assembly, you
will see that the center of the R.A. shaft is hollow. Additionally, if you look at the dec axis, you will see that it has a
sliding cover (the SIGHT HOLE /CABLE ACCESS COVER). By sliding this cover to the “open” position, you open a sight
line through the RA axis and out into the sky. For your rough alignment, you will peer through this sight tube and
attempt to center Polaris.
9

3. Azimuth adjustments: To begin, move or turn the entire pier or tripod east or west until the mount is oriented
approximately towards the pole (an imaginary line drawn through the hollow shaft). If you are using the 6” Eagle
Adjustable Folding Pier, you can take advantage of the Azimuth Adjustment Slots for your rough polar alignment.
The compass on the east side of the POLAR FORK BASE will help you. Also, if you want the mount to be level, check
the bubble level again after moving everything. (Remember, this is not critical for most observers.)
Loosen the two AZIMUTH LOCK KNOBS (one on each side of the POLAR FORK BASE). Use the two fine AZIMUTH
ADJUSTER KNOBS, one on each side of the mount, to make adjustments. You must back off the opposing azimuth
knob in order to move the other knob in that direction. Please refer to the photos above. These photos also
illustrate the 25 degrees of azimuth adjustment possible with this mount. If you are finished, i.e. for casual
observing, tighten the AZIMUTH LOCK KNOBS and make sure that the AZIMUTH ADJUSTER KNOB you were backing off
in the above adjustment is snugged against the AZIMUTH ADJUSTING PIN. If you will be further refining your
alignment, just snug down the AZIMUTH LOCK KNOBS.
One full turn of the AZIMUTH ADJUSTER KNOB is approximately 1.37 degrees (82 arc minutes)
4. Altitude (latitude) adjustments: The altitude adjustment mechanism on the
Mach1GTO has two components. There is a large ALTITUDE ADJUSTMENT KNOB on
the front (north) side of the mount for making the adjustments. The second part
is the innovative tool-free ALTITUDE LOCKING LEVER on the west side of the POLAR
FORK BASE. This lever has a spring-loaded, ratchet-type action that allowed us to
use a longer handle for leverage than would otherwise have been possible.
Pulling the handle out away from the base (pull it to the west) will disengage the
handle so that it will turn freely in either direction. Using this feature, you simply
ratchet it tight when your altitude is set, or ratchet it loose if you need to make an
adjustment. To start your altitude adjustment, loosen the ALTITUDE LOCKING
LEVER. Move the polar axis up or down with the large ALTITUDE ADJUSTMENT KNOB
located in the front of the polar axis assembly. When your altitude is set, lock it
with the locking lever. In addition, if you are using an Astro-Physics Portable
Pier, we have found that using the turnbuckle on the north leg of the pier also
can make fine altitude adjustments, if used.
One turn of the ALTITUDE ADJUSTMENT KNOB is approximately 1.04 degrees (62
arc minutes).
10

5. Continue your azimuth and altitude adjustments until you can sight Polaris in the polar alignment sight hole. Try to
center it roughly in the sight hole. A very dim red light may help you see enough of the hollow shaft to help you
with centering without obscuring Polaris. At this point, you have achieved a rough polar alignment, which may be
sufficient for casual visual observations, if you are not planning to slew to target objects with the keypad. When the
R.A. motor is engaged (the power is plugged in), it will compensate for the rotation of the earth and keep the target
object within the eyepiece field-of-view. Your target object will slowly drift since polar alignment at this stage is only
approximate. However, you can make corrections with the N-S-E-W buttons of your keypad controller.
6. Tighten the ALTITUDE LOCKING LEVER and AZIMUTH LOCK KNOBS by hand.
11

Attach Mounting Plate
(purchased separately)
Several mounting plates (also called cradle plates) are available for the Mach1GTO mount. If you own more than one
instrument, you may need more than one plate, or you may wish to use one of the dovetail mounting plate options with more
than one male dovetail sliding bar. Attach your mounting plate with the screws provided with the plate. It is important to use
the proper screws, please refer to the instruction sheet entitled “Mounting Plate Fastener Chart.” This chart is available at
the end of this manual and in the technical support section of our website.
15" FLAT MOUNTING PLATE (FP1500)
This plate is 15" long by 4.6” wide by 0.5” thick. Two pairs of keyhole slots
that measure 3.2" between centers are provided. The pairs are 13.75"
apart. You can drill additional holes to suit your needs. This plate also fits
the 400 and 600E German Equatorial mounts.
This plate has a hole spacing of 13.75”. This allows the use of the 15”
dovetail plate (DOVE15) on top of your instrument as an accessory plate.
Attach this plate with four 1/4-20 x 5/8" socket head cap screws
18" FLAT MOUNTING PLATE (FP1800)
This plate is 18" long and 7.5" at its widest point in the center. The
width of the plate tapers to 5.5" at each end. Four pairs of keyhole
slots that measure 3.2" between centers are provided. The two
inner pairs are 13.75" apart and the outer two pairs are 17" apart.
You can drill additional holes to suit your needs. This plate also
fits the 900 and 1200 German Equatorials.
Attach this plate with four 1/4-20 x 1 1/4" flat head socket cap
screws. Leave two screws in the dec hub’s top plate. (see note at
end of this section)
This plate has a hole spacing of 13.75”. This allows the use of the 15” dovetail plate (DOVE15) on top of your instrument as
an accessory plate.
Note: This is a very large plate for the Mach1GTO. If your instrument requires such a large plate, it may be too large for this
mount.
15” RIBBED MOUNTING PLATE (900RP)
The finished plate is 0.75" thick, 15" long and 6.5" at its widest point. The
width of the plate tapers to 4.75". A pair of keyhole slots that measure 3.2"
between centers are provided at each end. The distance between these
pairs of holes is 13.75". Due to the ribbed structure, you may not be able to
drill additional holes to suit your mounting rings. The plate weighs 2.3 lbs.
Attach this plate with four 1/4-20 x 1 1/4" flat head socket cap screws.
Leave two screws in the dec hub’s top plate. (see below) Note that the
plate is asymmetrical. In most cases, orient the plate so that the long end
points toward the sky. You can also turn the plate in the other direction to
balance your scope.
This plate has a hole spacing of 13.75”. This allows the use of the 15”
dovetail plate (DOVE15) on top of your instrument as an accessory plate.
8” ASTRO-PHYSICS DOVETAIL MOUNTING PLATE (DOVE08) with Q4047
ADAPTER
This versatile plate is suited for the 105 f6 Traveler and 130 refractors (we prefer the 15" Dovetail
Plate for most applications of the 130 f8 StarFire EDT) and other short instruments. The knob
assembly features a brass pin with a tapered end to hold your sliding bar firmly without marring the
aluminum. Use with the 7” or 10” sliding bars (SB0800 or SB1000), which are sold separately.
Repositioning the sliding bar will aid in adjusting the balance of your instrument.
Note: This plate requires the use of the Q4047 adapter with the Mach1GTO mount to provide
clearance for the knobs.
As an accessory plate - Attach to the top of our Astro-Physics mounting rings (tube diameters 5"-8") or
rings from Parallax Instruments that have the Astro-Physics hole pattern (you can request it). You must
also use a sliding bar on the bottom of the rings with the same distance (6.3" from center to center), i.e.
the SB0800 or SB1000.
Attach the Q4047 to the mount using four of the six outside holes and four 1/4-20 x 1” flat head socket
cap screws. Attach the DOVE08 to the Q4047 with four 1/4-20 x 58 socket head cap screws.
12

15” ASTRO-PHYSICS DOVETAIL (DOVE15) FOR 15” SLIDING BAR (SB1500)
The 15" version of our dovetail plate is suited for the 130 f8 StarFire
EDT, 155 f7 StarFire EDFS, Takahashi scopes and other instruments of
similar size. The two knob assemblies each feature a brass pin with a
tapered end to hold your sliding bar firmly without marring the aluminum.
Use with the 15" Sliding Bar (SB1500), which is sold separately (NOT for
use with Losmandy “D” plates). Also makes a great accessory plate
when used with either the 900RP, the FP1500, the FP1800 (with rings
mounted to inside holes) or another DOVE15.
Attach with four 1/4-20 x 1/2” flat head socket cap screws.
8.5” DOVETAIL FOR LOSMANDY D SERIES PLATE (DOVELM2)
This Astro-Physics plate attaches to the 400, 600E, 900, 1200 and Mach1GTO mounts. If
you already own one of the Losmandy DAP series (fits Astro-Physics refractors), DC series
(for Celestron 8" 9.25” or 11" SCTs) or DM series (for Meade 8" and 10" SCTs) plates, you
should consider this plate or the longer DOVELM16S. For larger size SCT’s we recommend
the longer DOVELM16S – see below.
Note that the two larger bolt-hole patterns are offset from the center. This allows you to
position the plate either forward or backward depending on the balance point of your
telescope. Attach this plate with four 1/4-20 x 5/8" socket head cap screws.
16" DOVETAIL FOR LOSMANDY D SERIES PLATES (DOVELM16S)
This Astro-Physics plate attaches to the 900 and Mach1GTO
mounts. If you already own one of the longer Losmandy DAP series
(fits larger Astro-Physics refractors), DC series (for Celestron 8" or
9.25" SCTs) or DM series (for Meade 8", and 10" SCTs) plates, this
is the mounting plate for you.
Note that the bolt-hole pattern is offset from the center. This allows
you to position the plate either forward or backward depending on the balance point of your telescope. AAttach this plate with
four 1/4-20 x 7/8" socket head cap screws.
NOTE ON ATTACHING THE ABOVE MOUNTING PLATES:
Three of the components listed above have six mounting holes that match the six screw holes that hold the DECLINATION HUB
PLATE onto the hub of the Mach1GTO’s Dec axis. (FP1800, 900RP and Q4047) We recommend that you use only four of
these holes to mount your plate. Remove four of the screws that hold the DECLINATION HUB PLATE in place. They will be
replaced by the four screws that hold the mounting plate down. The remaining two can then still hold the DECLINATION HUB
PLATE in place on the DECLINATION AXIS HUB while the mounting plate is being attached. The four remaining holes are more
than adequate to hold the plate securely on the mount. It really doesn’t matter which four you choose, but the two screws
left to hold the DECLINATION HUB PLATE in place should probably be opposite each other.
You will also notice that in addition to the four holes that make up the inside pattern on the DECLINATION HUB PLATE, there is
an extra hole that matches an extra hole found in both the Losmandy style plates (DOVELM2 and DOVELM16S). This fifth
hole is not needed if the four regular holes are in use. However, if you lose a mounting screw, it can be used in place of the
two normal holes on that end of the plate to make a very solid 3 point attachment.
Assemble Counterweight Shaft
IMPORTANT: Always attach the counterweights before mounting the telescope to the cradle plate
to prevent sudden movement of an unbalanced tube assembly, which may cause damage or injury.
Remember counterweights are heavy and will hurt if they fall on your foot.
1. Thread the COUNTERWEIGHT SHAFT onto the Dec. axis. Be careful to NOT cross-thread the shaft in the adapter!
2. Remove the COUNTERWEIGHT SAFETY KNOB AND WASHER (or the one-piece Safety Stop if you are using the 1.875”
diameter shaft) from the base of the COUNTERWEIGHT SHAFT. Add sufficient COUNTERWEIGHTS (purchased
separately) to the COUNTERWEIGHT SHAFT to balance the telescope you intend to use. Loosen the counterweight
knob and hold the counterweight with the knob pointing downward so that the brass pin will move from the center
opening allowing the counterweight to slide into position. Always use two hands to attach or move the
counterweights on the shaft. It is advisable to have the counterweight knob pointing down toward the pier. This
will minimize the chance of accidentally loosening the counterweight during the observing session.
3. Reattach the COUNTERWEIGHT SAFETY KNOB AND WASHER to the end of the COUNTERWEIGHT SHAFT.This will help
to prevent injury if someone accidentally loosens the COUNTERWEIGHT KNOB.
NOTE: A firm tightening of the COUNTERWEIGHT KNOB will not damage the surface of the COUNTERWEIGHT SHAFT. The pin that
tightens against the stainless counterweight shaft is constructed of brass. Likewise, the bronze sleeve that has been press
fitted into the center of the COUNTERWEIGHT will prevent marring of the shaft as you move the COUNTERWEIGHTS up and down.
13

Optional 10.7” x 1.875” Counterweight Shaft
The optional 10.7” total length x 1.875” diameter Counterweight Shaft offers some additional
capabilities and considerations. The shaft installs in the same way as the standard shaft, but
instead of a SAFETY KNOB AND WASHER, this shaft uses the One Piece Washerless Safety
Stop (M12676) at the end of the shaft. For safety, you
MUST use this Safety Stop! There are two main
reasons why a person might choose the Optional
Counterweight Shaft over the standard 14.5” x 1.125”
shaft:
1. Owners of 900 or 1200 series mounts might
prefer to purchase the optional shaft because it
uses the same 10 lb. (10SCWT) and 18 lb.
(18SCWT) counterweights that those bigger mounts use. These counterweights
have larger 1.875” diameter center holes. Please note that this shaft weighs in at
a hefty 7.7 lbs. including the safety stop. To facilitate lighter instruments, we
have added a 5 lb. counterweight (5SCWT) to the product line to join the other
two weights with the larger center holes.
2. Owners who plan to use their Mach1GTO for long-distance travel may wish to
purchase this shaft for a more compact fit in a travel case. The 10.7” shaft was
specifically designed to fit inside the hollow declination shaft and screw into the
COUNTERWEIGHT ADAPTER from the back side. When fully screwed into the
adapter, and with the Safety Stop in place, the whole thing only protrudes
about 3/4” from the face of the DECLINATION HUB PLATE. To prevent you from
accidentally getting the shaft stuck inside the dec axis, we added a socket
head screw to the end of the
shaft. Simply use your 1/4” hex
key to break it loose if needed.
Keep in mind that the combined
weight of the equatorial head
and shaft will be 36.2 lbs. not
counting the GTOCP3 control
box, keypad, cables or the travel
case itself. With the mount’s two axes separated, and the shaft thus stored, it will all fit neatly into a case that should fit
into an overhead luggage compartment, but you still have to be able to lift it up that high! You must also be aware of all
rules and regulations regarding weight limits and allowable case sizes, not to mention potential security problems.
Please do your homework before trying to take a trip with your valuable astronomical equipment. We have designed
the mount to be portable, but we cannot guarantee that you will be allowed to carry it with you.
One final caution: This is a “really cool” feature, but remember, you will need to remove the mounting plate to take
advantage of this capability. It will be great for long-distance travel, but you may not want to store the shaft inside the
dec axis for trips to and from your favorite local dark site.
Attach Mounting Rings
(purchased separately)
Flat and ribbed plates: constructed with keyhole slots at the location where your mounting rings attach. This feature
enables you to partially loosen the screws on your rings just enough to insert them into the larger part of the keyhole, then
slide the rings to the narrow part and tighten them with a hex key. You can even accomplish this with the rings on the scope,
although this maneuver may be difficult to accomplish with a large, heavy instrument.
We prefer this keyhole method to the standard way of completely removing the screws and possibly dropping them in the
grass.
Astro-Physics or Losmandy Dovetail Plates: Attach the mounting rings to the male dovetail plate (sliding bar).
Fine Polar Alignment
For casual observation, you may skip this section and simply start observing. Don’t forget to tighten your ALTITUDE LOCKING
LEVER and AZIMUTH LOCK KNOBS and make sure both of your AZIMUTH ADJUSTER KNOBS are snugged against the AZIMUTH
ADJUSTING PIN. Move the telescope manually or by using the N-S-E-W buttons of the keypad. The keypad and GTO Servo
Control Box will function as soon as they are plugged in. That means that the R.A. axis will be tracking up to the limits of
your polar alignment. However, if you plan to use any of the go-to functions of the Mach1GTO or do astrophotography, you
must perform a more accurate polar alignment.
14

Methods for fine polar alignment
•Polar Alignment Scope – Use our optional polar scope (PASILL4 or PASILL3 (prior version) models – earlier polar
alignment scopes cannot be used as effectively with the Mach1GTO as explained later in this section). This will allow
you to quickly align your mount on the pole stars. The reticle was designed for use in both the Northern and Southern
hemispheres. Even users of the GTO computerized mounts will find these polar scopes useful, particularly if your
telescope is not orthogonal to the mount (please refer to the keypad manual for a discussion of orthogonality). If you
have a PASILL4 or PASILL3, please read the instructions sheets that came with it with the following modification:
The reason that the Mach1GTO requires either the PASILL4
or PASILL3, is that these polar scopes have reticle housings
that turn freely in their collars. Unlike all the other mounts
that we have produced since the early 1990’s, the
Mach1GTO’s polar axis shaft does not reach all the way to
the bottom of the polar axis housing. With these other
mounts, the polar scope was actually screwed into the end of
the polar axis shaft. If you turned the polar (RA) axis, the
polar scope turned as well. With the Mach1GTO, the polar
scope attaches to the POLAR SCOPE ADAPTER, which is in turn,
attached to the polar axis housing, not the polar shaft.
Turning the polar axis does NOT also turn the polar scope.
To use the polar scope with your Mach1GTO, simply turn the
polar scope’s reticle housing instead of the RA axis as
instructed during the final stages of polar alignment. If you
started with the reticle properly oriented these will be small
movements.
It is possible to use an older model polar scope (PASILL or
PASILL2), but they may be a bit less accurate. To use one of
these earlier polar scopes, screw the unit into the adapter,
and then back it off to align Polaris’ relative position to the
pole. Proceed normally turning the polar scope wherever the
instructions say to turn the RA axis. Since the scope won’t be
screwed in tight, you may have a bit of sag that will slightly
reduce your accuracy.
•GTO Keypad – Please refer to the instruction manual for the GTO Servo Drive and read the section describing the
startup sequence. For daytime setup, read the section entitled “Polar Aligning in the Daytime” in the GTO Keypad
manual.
•Star Drift method – Traditionally, this has been regarded as the most accurate method of polar alignment, however it
is also the most time consuming. If you are planning long exposure astrophotos, we suggest that you use the Polar
Alignment Scope (see above), then tweak the final polar alignment by star drifting. Refer to the GTO Keypad manual
for hints on polar aligning using a GTO Quick Star Drift method. Also refer to the Technical Support section of our
website for further information. For general information regarding traditional star drift alignment, please refer to the
recommended reading list at the end of this manual.
Altitude and Azimuth Adjustments
1. Loosen the ALTITUDE LOCKING LEVER and barely loosen the two AZIMUTH LOCK KNOBS. When adjusting azimuth,
remember that you must back off with one AZIMUTH ADJUSTER KNOB to move the other.
2. Follow one of the methods of fine polar alignment mentioned above.
3. When polar alignment has been achieved, tighten the ALTITUDE LOCK LEVER. Make sure that the AZIMUTH
ADJUSTER KNOB that you have been backing off is turned back in until it is against the AZIMUTH ADJUSTING PIN so
that the mount is held firmly in azimuth. Tighten the AZIMUTH LOCK KNOBS.
4. For a portable installation, the ALTITUDE LOCKING LEVER and the AZIMUTH ADJUSTER KNOBS do not need excessive
tightening. You can tighten with more force for a permanent installation.
15

CLUTCH KNOBS AND BALANCING
R.A. and Dec. Clutch Knobs
1. What do they do?
The three R.A. and three Dec. CLUTCH KNOBS have the function of connecting the R.A. and Dec. axes to their
respective drive worm wheel gears. Their function is progressive, from no tension (axes free to move - as required
during correct balancing of the telescope) to a completely "locked up" state.
2. How can you find out what they really do?
As shipped, all Mach1GTO mounts have all three R.A. and Dec. CLUTCH KNOBS firmly hand tightened. This will give
you a good idea of the maximum tightness (clutch action) that can be achieved by hand effort alone. At this point,
you must bear in mind that for optimum performance all three CLUTCH KNOBS on each axis (R.A. or Dec.) should be
tightened evenly with the same tension (i.e. all three half tight, all three fully tight, etc.).
In order to feel the effect of the CLUTCH KNOBS, you may wish to assemble your mount with the mounting plate and
COUNTERWEIGHT SHAFT. Do not put scope and COUNTERWEIGHTS on at this stage. With the above assembly (with the
CLUTCH KNOBS firmly hand tightened - "as shipped"), you can feel the amount of force needed to move each axis by
hand. Grab each end of the telescope mounting plate and move it with a backward and forward movement of the
Dec. axis. You will feel considerable resistance to this motion. Perform the same operation on the R.A. axis by
moving the counterweight shaft backward and forward. With a well-balanced telescope, the above tightness of the
clutch knobs will be sufficient for all normal conditions of use.
Now, mount up and balance your telescope so you can "feel" what this resistance in R.A. and Dec. (movement
backwards and forwards) is like when you make these motions from the eyepiece end of your telescope as you
would during normal use when slewing (pushing) by hand to acquire an astronomical object within the field of view
of your finder or scope.
3. How tight can the clutch be and can you do any damage by over-tightening them?
These clutches can be tightened as much as needed. There is no danger of over-tightening. You will see that
each clutch knob has a 3/16 hex socket for tightening with an Allen key. Using the provided hex key you can lock
up the clutches so that only the worm drives are able to move each axis. You should NOT attempt to push your
scope by hand against this "locked up" resistance, or undue stress will be placed on the worm wheel, worm gear
and bearings.
Most users will never need to use a hex key on their Mach1GTO’s clutches, but if you are heavily loaded, if your
system is out of balance, or if you are doing critical long exposure astro-photography, you may wish to have the
extra clutch tightness. As a general rule, if you have a big scope (6" refractor or 10” SCT) with all the accessories,
you will need more clutch tension than a 4" or 5" scope.
Balancing Your Telescope
For proper operation, the telescope must be adequately balanced along both axes. Start by balancing the tube assembly.
First, Balance the Declination Axis.
1. Position the mount for balancing. Move the R.A. axis so that the COUNTERWEIGHT SHAFT is pointing down. The
declination axis assembly will be in the meridian (this is the classic photographic pose for a German Equatorial).
Position the Dec. axis so the telescope tube is horizontal and pointing east.
2. Tighten the 3 R.A. axis CLUTCH KNOBS.
3. Loosen the 3 Dec. axis CLUTCH KNOBS (about 2 to 3 full turns) so that the telescope moves freely about the
declination axis. NOTE: because of a spring mechanism, you must loosen the knobs past where they begin to feel
loose. Be careful because if your telescope is significantly out of balance, it may swing rapidly in the out-of-
balance direction!
4. Loosen the tube mounting rings and slide the tube back and forth for balancing. This is best done with the tube in
the horizontal position. If you are using a dovetail mounting plate, slightly loosen the hand knobs on the female
dovetail receiver plate and slide the male sliding plate (and thus the telescope) to the desired position.
5. The scope is balanced when it stays put (does not move) with the clutches loose and movement back and forth
about the declination axis has the same feel in both directions. Be mindful of eyepieces, cameras and other
accessories that are yet to be added and compensate accordingly.
6. Re-tighten the telescope mounting rings or mounting plate dovetail clamps!
16

Second, Balance the Polar Axis
1. Now, tighten the DECLINATION CLUTCH KNOBS and position the mount with the telescope horizontal and the
declination axis horizontal. The COUNTERWEIGHT SHAFT is now horizontal with the center of the COUNTERWEIGHTS
the same height as the middle of the tube.
2. Loosen the R.A. CLUTCH KNOBS (also about 2 to 3 turns). Again, be careful because if your scope is significantly un-
balanced, it may swing rapidly in the out-of-balance direction.
3. Move the COUNTERWEIGHT(S) up or down to achieve the correct balance in R.A. Again, movement back and forth
about the R.A. axis should have the same feel in both directions.
4. Re-set the tightness of all 6 CLUTCH KNOBS to the resistance you want making sure that each axis’ 3 clutches are
evenly tightened. (See section on CLUTCH KNOBS above.)
Try to anticipate any balance problems due to the extra weight of diagonals, heavy eyepieces, finders, solar filters, etc. If the
scope moves by itself, when the clutches are loose, then the scope is not balanced adequately. You may want to “tweak” by
carefully repeating steps 1 – 5 after everything has been attached to the telescope. Be especially careful loosening the Dec.
clutch knobs.
Note: A small amount of imbalance on the East side of the mount is permissible and even desirable for astrophotography
and imaging. This allows gravity to keep the drive train fully engaged while tracking throughout the exposure. If you
intentionally create this small imbalance, you must remember to re-adjust the balance whenever you flip from one side of the
mount to the other. Forgetting to re-adjust can result in a slight see-saw action in tracking that could spoil your next image.
CABLE MANAGEMENT
Introduction to one of the Mach1GTO’s most Innovative Features
In years past, there was no such problem as cable management on astronomical equipment. The only wires or cables would
have been for the clock drive motor of the RA axis, and maybe one for a drive motor attached to the dec’s tangent arm. Today,
we have added the cables that accompany film cameras, CCD cameras, autoguiders, multiple dew heaters, motorized focusers,
and numerous other electronic accessories. Many modern imaging setups have wires going everywhere, and these wires could
be a never ending source of problems and frustrations for the operator. Wires hanging off of cameras can lead to image ruining
flexure. Wires can catch and snag as the mount slews, and were especially vulnerable when a German Equatorial Mount was
“swapping sides” to point at the other side of the meridian. The problem was that all these wires going to all these different
locations had to deal with a mechanical system that was designed to be in motion.
Roland Christen and the design team at Astro-Physics came up with an elegant solution to the “cable nightmare.” If cables all
around the mount are a problem, then run them through the mount! The idea seems absurdly simple, but it introduced some
significant engineering and design challenges, particularly since this mount is portable and the two axes come apart. Those
challenges were met with the Mach1GTO. There are four places on the Mach1GTO where cables can enter or exit the inside of
the mount.
1. The first of these is the hub end of the dec axis. Underneath the DECLINATION HUB PLATE on the end of the declination
axis are two CABLE CHANNELS. Cables passing through the hub get routed through one of these channels and on to
their accessory. This is where imaging cables, dew heater cables and motorized focuser cables are most likely to be
routed.
2. The second point of egress is the SIGHT HOLE /CABLE ACCESS COVER on the dec axis. You can run the dec leg of your
servo drive’s Y-cable out through this opening. It is also a very convenient place from which to feed cables.
3. The third place to run cables in and out is the CABLE ACCESS COVER on the RA axis. This is an especially useful place
if you need to do a rough polar alignment each time you set up. It still allows the easy use of the polar scope.
4. Finally, for permanent installations or regular observing spots with marked pier / tripod positions (in other words,
observing sites where you don’t need the polar scope) the cables can be run out the bottom of the RA axis.
Which of these openings you use will depend on your particular situation. All of the openings and internal cable passages have
a two inch diameter clearance that will accommodate a DB15 serial plug with relative ease. It is certainly not required that you
run any cables through the mount, but many of you will find this feature useful.
Preparation
Your approach to cable routing will depend on two main factors: the particular cables you need to run and the degree of
portability of your system. These factors lead to a couple of questions: Will the telescope’s mounting plate remain attached to
the mount between observing sessions? Is the mount often removed from the pier / tripod between sessions? Do you need to
rough polar align each time you set up or can you set up and always be close enough to not need a polar scope? Or are you
17

permanently mounted? Since everyone’s situation will be a bit different, these instructions are more guidelines rather than
specific “follow these to the letter or else” instructions.
If it is practical, you may find it most convenient to first set up your mount following the above instructions and get it pretty well
polar aligned. The two axes must be assembled to run your cables. You won’t do a final drift alignment yet, but you will want to
get close. This is especially the case for those of you who are using a polar alignment scope like our PASILL4. You do not want
to have the polar scope installed when the cables are being run through the inside of the mount or you might scratch the polar
scope’s objective. However, as you will see, there is a way to use your polar scope with the cables already in place, though this
may not be possible in all cases. Do not have your telescope or mounting plate attached yet.
Remove the DECLINATION HUB PLATE off of the DECLINATION AXIS HUB by removing the six 1/4-20X 3/4 FLAT HEAD SOCKET CAP
SCREWS around its perimeter. Remove the polar scope from the RA axis if you are using one. Finally, remove the POLAR SCOPE
ADAPTER (with POLAR SCOPE CAP) and raise the two CABLE ACCESS COVERS (one on each axis) to the open position. You are now
ready to put in your cables. Note: starting in April, 2007 with Ser. # M10053 the POLAR SCOPE ADAPTER is a bit larger and has a
knurled grip for easier removal.
Cable Installation – the First Time
Cables can be inserted either from the top (through the
DECLINATION AXIS HUB) or bottom (through the polar scope
end of the RA axis), but the simplest way will usually be to
insert the cables through the SIGHT HOLE /CABLE ACCESS
COVER on the declination axis. The easiest trick for
inserting the cables, if you will be routing cables out
through the DECLINATION AXIS HUB (as is likely), is to turn
the RA axis so the COUNTERWEIGHT SHAFT ADAPTER is
pointing up and south and let gravity do the work. Always
start by running the cables with the largest connectors
first. Insert the telescope end of the cable into the SIGHT
HOLE /CABLE ACCESS COVER on the dec axis and guide it
“down” and out the DECLINATION AXIS HUB. Insert the
opposite end in the same opening and guide it either out
the RA’s CABLE ACCESS COVER or out the bottom of the RA
axis. If you are routing out the RA’s CABLE ACCESS COVER,
you can reach in the bottom of the RA axis to help you
guide the cable end out the access hole.
When all the necessary cables have been run through the
mount, turn the RA axis so that the mount is in its normal
position with the COUNTERWEIGHT SHAFT ADAPTER pointing
down and north. Adjust the amount of each cable that you
will need sticking out through the DECLINATION AXIS HUB to adequately reach its
electronic device. When determining the length, be sure to run the cable
through the CABLE CHANNEL and allow enough slack so that there will be no
tension on the cable’s plug. Make sure you allow for focuser travel. Don’t allow
too much slack, however, or you will defeat the whole purpose of hiding the
cables inside the mount. Be sure that you route each cable through the
appropriate CABLE CHANNEL side for the side of the telescope where it will plug in.
Also, keep in mind any other places where you may wish to tie your cables like
on the end of a mounting plate. Cables for CCD cameras should be tied off to
the focuser or the very back of the mounting plate.
Once the cables are routed through the mount, and you have the proper amount
sticking out the top of the DECLINATION AXIS HUB, you are ready to replace the
DECLINATION HUB PLATE. Be sure that the cables are seated well in the two
CABLE CHANNELS and that they are not being pinched by the plate. Put in two
screws, one each on opposite sides of the plate and snug them down. Re-check
that none of the cables have been pinched and then tighten the two screws firmly. If you are using the FP1800, the RP900 or
the Q4047 (with DOVE08) as your telescope mounting plate, install it now using the four provided screws in the remaining four
holes. If you will be using one of the other telescope mounting plates (FP1500, DOVE15, DOVELM2 or DOVELM16S), first
install the remaining four screws from the DECLINATION HUB PLATE, and then install the mounting plate with the correct fasteners
that were provided.
Where the cables emerge (RA CABLE ACCESS HOLE or bottom of RA axis), make sure that nothing will be hanging or pulling on
any of the cables. You may wish to bundle the cables together and tie them off to a tripod leg or pier strut to eliminate potential
tripping hazards. Run them carefully to wherever they will be plugged in (laptop, heater controller etc.) and try to avoid creating
tripping hazards. If you have run the cables out the RA’s CABLE ACCESS HOLE, replace the POLAR SCOPE ADAPTER and POLAR
SCOPE CAP. Do NOT over-tighten the POLAR SCOPE ADAPTER.You can also partially close the SIGHT HOLE /CABLE ACCESS COVER
18

on the dec axis and the CABLE ACCESS COVER on the RA axis at this time. They can’t be closed all the way with cables routed
through them but they can be closed enough to keep most dirt and dust out.
Disassembly and Subsequent Setups and Polar Alignments
Once you have gone to all this effort, you won’t want to undo everything for relatively simple tear-down and set-up situations.
And you won’t have to! The degree to which you must disassemble the cabling depends on the degree to which you must break
down the mount. If you need to disassemble the mount for airline travel, you will unfortunately need to undo everything. If you
simply move your entire assembly in and out of the garage on its pier or tripod, you will hardly need to take anything apart. Most
of us are somewhere in between. Disassembly steps are basically the reverse of the installation steps above and really don’t
need further elaboration. The main point is that you will want to avoid complete removal of the cables that involves taking off the
DECLINATION HUB PLATE if that is possible for your situation.
The real question is: how can subsequent setups be done easily, and how can a person polar align with all those cables in
there? Fortunately there are two easy solutions. First, if you regularly need to use your polar scope and you are only running a
couple cables through the mount, just make sure that your cables were run out the RA’s CABLE ACCESS HOLE. If you use this
feature, you can insert and use the polar scope without any problem. (You may need to tug lightly at a cable to get it out of the
line of sight when aligning.) The cables can simply be left in place and wrapped around the mount for most transport and storage
situations. You simply need to take care not to pinch the cables anywhere or to strike a connector on the exterior surfaces of the
mount, which could cause a scratch. Then, just set up the mount with the cables already in place.
But what about polar alignment if the cables have been run out the bottom of the RA axis or if there are very many cables?
Simple! Set your mount up on its tripod or pier, but don’t tie off or hook up any of the cables from the bottom of the RA axis yet.
Now, open the SIGHT HOLE /CABLE ACCESS COVER on the declination axis. Push the cables up from the bottom of the RA axis
with one hand and hook them with a finger through the sight hole. Now pull the bottom part of the cabling out through the hole
and hang the cables out of the way. Insert your POLAR SCOPE ADAPTER to rough polar align (don’t over-tighten), and then put in a
polar scope to get a good polar alignment. When you are as close as you can get, pull off the polar scope and adapter, and
reinsert your cables through the SIGHT HOLE /CABLE ACCESS COVER. You are now ready to tie them off, plug them in and go!
A Note on the Mount’s Servo “Y” Cable
The “Y” cable that connects your GTOCP3 control box to the servo motor gearboxes can be run either inside or outside the
mount. The Mach1GTO
doesn’t really have
anything that will catch
the cables, but you still
may want to run them
inside. This is one
cable that will not be run
out through the
DECLINATION AXIS HUB.
To insert the “Y” cable,
put the control box end
into the SIGHT HOLE /
CABLE ACCESS COVER
on the declination axis.
Run it out through the
RA’s CABLE ACCESS
COVER, and pull the
shorter RA leg of the
cable all the way
through. (Again, if the
POLAR SCOPE ADAPTER
is removed, you can
easily guide the control
box plug out the CABLE ACCESS COVER of the RA axis.) Only the declination portion will be left inside the mount. Connect all
three plugs. When you remove this cable, don’t reverse the procedure; simply pull the declination leg on out through the RA’s
CABLE ACCESS COVER.
A Few More Hints and Tricks
•If you need to remove a cable completely from the mount, mark the point where it emerges from the CABLE CHANNEL in
the DECLINATION ACCESS HUB. Wrapping the cable at that point with a small piece of colored electrical tape works well.
That way you won’t need to re-measure to position the cable properly.
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