for Vixen GP

Installation Guide of Telescope Drive Master

Encoder-adapter for Vixen GP mounts


Please start with reading this important message below!!!

I have made this installation guide below, together with taking demo-pictures, using the original Heidenhain-type, locating pin based encoder coupling. But, during continuous product development process, I replaced it by the new, much more accurate coupling-version.

Obsolete coupling:

New coupling:

Unfortunately, I do not have a chance to correct the old pictures and the relevant parts of this installation guide because this telescope mount is not in my observatory nowadays. So please ignore the instructions of the pin-based coupling installation here and, instead of these points, use the description of the new coupling installation guide based on the page above. The rest of the adapter installation process has remained the same.

At the same time, if you need any additional help regarding this issue, please do not hesitate to write me to my e-mail address which can be found on the Contact page within Company Details.


First of all, thank you very much for purchasing our product called "Telescope Drive Master" and congratulation for your decision. This system will improve the tracking accuracy of your Vixen GP equatorial mount dramatically independently from its original periodic error amplitude because both periodic and aperiodic errors of your mount will completely be eliminated using our real time, ultra high precision correction system, without using conventional autoguider. We guarantee that your tracking error will remain within 1" (one arc-second) range total (or ±0.5") within 95% of your exposure time. It means your mount will have the best tracking ability among the amateur and semipro equatorial mounts all over the world (even if your dome-shutter is closed...).

To achieve this unbelievable result, before the installation of your Telescope Drive Master, you need to complete a very accurate polar alignment process of course. Please find our proposed method to do that on the companion CD ROM or among website's documents.

TDM controlling system contains two main logical units or parts: a high precision encoder unit (encoder and its mechanical adapter) attached directly onto the RA shaft of the mount and an electronic device (a sort of "black-box" with connectors), which receives the electrical signals arriving from the encoder unit and sends control instructions to the mount's driver via its auto-guider input connector. So you will need to install the mechanical elements and the electronic device as well but do not worry: both of them can be done very easily.

Please find the drawing and description of electronic connections to be set in relevant part of User's Guide because this schematic is the same for every telescope mount. In this document you will find the mount specific instructions for mechanical adapter and encoder installation only.

Before starting it is highly important to emphasize that both encoder unit and its adapter elements are sensitive mechanical parts!!! Do not drop any of them; do not stress them during installation!!! Handle with care! Any damages of these parts can destroy product's accuracy.

Just two Allen-wrenches (1.3mm and 2mm type), a Torch screwdriver (size# T9), a spanner in size 22mm, some metal glue (e.g. Loctite) and a small hammer will be needed for installation.

You need to find a small plastic bag within encoder box with small particles as seen below.



Mechanical parts of the adapter have been assembled in one unit before delivery. The risk of any mechanical damage during transportation is much lower in this way but, it means, you need to disassemble them before installation. You just need to remove those screws (with 2mm Allen-wrench) which fix the cover of the encoder unit onto the adapter stator as you can see below.



Before assembling parts during installation, please always check and clean all of the threads and surfaces of the lower end of the RA shaft and encoder adaptor elements if necessary. Use clean clothes (not nylon!) for smooth surfaces and a dry toothbrush to clean the internal and/or external thread(s) of the RA hollow shaft if it is necessary. Only the clean and tight mechanical contact between surfaces will provide correct mechanical coupling and positions.



Step 1:

Remove the plastic cup of the polar scope.



Step 2:

Rotating it in counterclockwise direction, please remove polar scope. (If you want to complete rough polar alignment using polar scope, please do it before this step.)



Step 3:

Please loosen RA scale fixing screw and remove graduated circle from RA casting.



Step 4:

Next step is attaching encoder shaft into the hollow shaft of RA axis. It is useful to fix the RA shaft of the mount against rotation before this point. Do not touch the long cylindrical surface of the encoder shaft with any metal tool (e.g. pliers)!!! Use spanner (size 22mm) only, maybe coach-wrench at the root of this part clockwise, as you can see below in the picture, and tighten it well enough. This part cannot have any offset compared to the RA axis. If shaft-threads and connecting surfaces are clean enough, the thread profile-angle will have to be able to centralize geometrical axes without any problem.

Image Image

Step 5:

Using a small hand-hammer if it is necessary (but applying just small knocks) push the attached tiny locating pin into its hole on the stator. The length of the pin remained out of the stator ring has to be between 10 and 12 mm only. Do not enlarge the diameter of this hole!!! Thanks to the tight fit, the pin has to be fixed without any slackness!!! To ensure correct and the most rigid position of locating pin or if you removed it from the hole (which is not recommended), and want to put it back again but the hole is not tight enough, please use some metal glue (e.g. Loctite) for fixing locating pin. If this pin can move just an extremely little bit than TDM will not work properly!!!



Step 6:

Now, push stator ring into the hole of RA casting completely and fix its position (with locating pin up) using scale set-screw. It is very important to fix this part against rotation using this screw (found on top of the RA casting) very well because stator cannot move at all.



Step 7:

Please install black plastic bucket into the encoder slot. It has to glide into its place firmly. Please find possible versions of encoder installation in the file called "Heidenhain.jpg": version 3 has to be applied for this type of adapter.



Step 8:

Now, after the glue (if applied) has dried and locator pin fixed well, please check the released clamps on both the front and back side of the encoder and push the encoder firmly onto the previously installed and clean steel shaft. The position of the plastic bucket has to fit to locating pin. The diameter of the locating pin is a bit larger than the slot in the plastic bucket so you need to push it a bit harder. Please do NOT apply hammer on encoder!!! You need to push it by hand and be careful: roughly 1 or 2mm gap has to remain between the surface of the stator and the encoder.



Step 9:

Using Torch screw (size#T9) tighten two screws well in the clamping ring on both ends of the encoder. You can reach the screw on the front side via one of the gaps created especially for this purpose onto the encoder body.

Image Image


Step 10:

The main parts of the encoder adapter have been installed so far. Now, please put the cover of the encoder to its place and fix it in proper position (cable slot is down) using the same screws dismounted as the very first step of this installation process. (A small difference in the position of the encoder and cover is not a problem; just push the cable into the empty space between the encoder and its cover.)


Step 11:

Finally, please screw the cap onto the encoder cover for saving encoder against environmental influences.

Image Image

Congratulation, you successfully installed the encoder onto your equatorial mount and you have finished the most difficult part of the installation process!!!

You just need to create cable connections among telescope electric units according to the relevant part of the User's Guide.

Additionally, please find several useful tips and tricks in the User's Guide of TDM and other documents found on companion CD ROM or visiting website.

original solarflare design by rhuk
modified by MDA-TelesCoop