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SV503 Series Telescope+ZWO EAF (Electronic Auto Focuser) Installation Guide

SV503 Series Telescope+ZWO EAF (Electronic Auto Focuser) Installation Guide

SV503 Series Telescope+ZWO EAF (Electronic Auto Focuser) Installation Guide

1. Introduction

Technical Level: Novice
Time Taken: 10-15 Minutes
SVBony SV503 Scopes (70/80/102)
1 Set of ZWO EAF (NEW/OLD model)
Tools required:
5/64 Allen key
3mm Allen key
M5 / M4 Allen Keys (Inc in ZWO EAF box)
2x M4 Screw (Inc in ZWO EAF box)
4x M5 Screw (Inc in ZWO EAF box) (may come with different length)
4x Spacers (Inc in ZWO EAF box)
Motor Bracket
1x Flexible Couple (Inc in ZWO EAF box) 

2. Method

1. Check all pieces from ZWO EAF are in the box (check the ZWO website to see what is included inside the box), and Assemble the motor bracket with a 2x M4 screw. (pic.1)

Pic.1 parts required from ZWO EAF BOX

2. Rotate the focuser for easy access. (pic.2)

 Pic.2 Focuser rotated

3. Locate the focus lock screw and Tension hold screw hole. (pic.2)

Pic.2 Focus Lock & Tension Hold Screw Hole

4. Remove the focus lock screw, but DONT TOUCH / REMOVE the Tension grub screw inside the hole. (pic.3) 

Pic.3 Focus lock screw Removed

5. Remove the single-speed focuser knob by loosening the grub screws (2 grub screws). (pic.4)

Pic.4 Loosen 2x Grub screw-on single-speed knob

6. Once the knob is removed, Attach the Flexible Couple (Inc in ZWO EAF box), You may need to check which bore size fits the focuser knob shaft, Once attached tighten the grub screw (2x to be tightened). (Pic.5)

Pic.5 Tighten 2 grub screw

7. Attached the Motor bracket with 2x M5 Screw*  + spacer (on each) into the Focuser lock screw hole and Tension hold screw hole. (Pic.6)
Make sure don’t tighten the bracket yet as this still needs to be adjusted.

* The M5 Screw may come with different lengths, If it does use the LONGEST M5 for step 7.

8. Insert the motor body on the flexible coupling then tighten the grub screw (2 grubs to be tightened). (Pic.7)

Pic.7 Motor body attached and Grub screw tighten

9. Align the MOTOR body with the Motor bracket as shown below (Pic.8), then attach the motor with the bracket with 2x M5 screw* + Spacer (Pic.9)

* The M5 Screw may come with different lengths, If it does use the Shortest M5 for step 9.

10. Adjust the motor bracket with hand (Pushing toward the body) to about just TOUCHING the motor body (Pic.10), Then tighten the screw on the motor bracket. (Pic.11)

                                                  Pic.10 Adjusting motor bracket                                     Pic.11 screw tighten

11. Congratulation your EAF is attached, Double check the bolt/screw to be sure is tight enough,  Then time for you to test to make sure all hold in place and work by moving the EAF using ZWO hand controller (Not supplied) / ASIAIR / Other ASCOM software.

If everything is correct, you will only end up with 2 parts that are being removed from the SVBONY SV503 series telescope. (Pic.12)

Pic.12 The only 2 parts you remove

Sample images if ZWO EAF attached correctly.
Thanks for your time.


Comment user


Thank you for this clear, well-documented instruction page! I have the SV503 /70EP and am adding the ZWO EAP! Your instructions made this very straightforward, quick, and easy! Svbony is quite an impressive company! Thank you again! Mark

Comment user


The EAF should be attached to the fine focus adjustment axle, not the coarse one. However, it is just not possible due to the way the scope is built. That is a design flaw that should be corrected in future OTA's. Attaching the EAF to the coarse focus adjuster, makes it to produce steps too large. Even when setting the step size to 1, the movement is too much from one position to the next. I love this scope and I'm planning to get a 550... If it accommodates the EAF the proper way.

Comment user


Thanks for making this guide.

Comment user


Can you also fit the eaf on the sv48p?

Comment author


yes, it can be.

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