Gemini G53F spare parts - motors and gears - Forums

Topic starter

Jan 22, 2025

Dear all,
I have been using Gemini G53f mount happily till now. The mechanical design as well as precision of this mount is fantastic. Few months ago I noticed some slip in the RA motor. I disassembled the motor according to this video: https://www.youtube.com/watch?v=NjaeGO3bHE0 and took it completely apart. I found the root cause of this problem.
There suppose to be a press fit between one shaft and the brass ring, but it is completely loose:

I tried to glue it, but it worked only for a while and got loose again.

Does anyone know where I can get the spare parts? The whole motor with the gear...
Unfortunetely, the manufacturer Andras Dan passed away few years ago and even his webpage geminitelescope.com is down.

Helpful Engaging

andrea tasselli

Frequent contributor

Jan 22, 2025

Are we talking about the RA stepper motor or the reduction gear? If it is the former that can be easily replaced. If it is the latter you need to repair if you're handy and have access to the required tooling (I have if you're stuck, PM me if you need further help). BTW, I have a G41 and have already repaired it.

Concise Supportive

Gordb

New contributor

3 days ago

Hi,

I am just wondering if you had any success repairing your G53F mount? My mount is fine but the Pulsar 2 control unit has failed. The hand controller works. I am looking to either have the Pulsar 2 unit repaired or updated to OnStep. My understanding for converting to OnStep is that the motors and encoders will need to be replaced and some wiring as well. I don’t have the skills to do this and am hoping that there is the possibility of some help please? I actually have an OnStep controller built but it never worked properly. It was after that that I discovered that the motors, encoders and wiring needed to be changed. Any help would be greatly appreciated as this is a fantastic mount and if I can avoid having to replace it that would be preferable. Many thanks!

Cheers,

Gord

Well written Respectful

andrea tasselli

Frequent contributor

3 days ago

Gordb · Sep 14, 2026, 12:32 AM
Hi,
I am just wondering if you had any success repairing your G53F mount? My mount is fine but the Pulsar 2 control unit has failed. The hand controller works. I am looking to either have the Pulsar 2 unit repaired or updated to OnStep. My understanding for converting to OnStep is that the motors and encoders will need to be replaced and some wiring as well. I don’t have the skills to do this and am hoping that there is the possibility of some help please? I actually have an OnStep controller built but it never worked properly. It was after that that I discovered that the motors, encoders and wiring needed to be changed. Any help would be greatly appreciated as this is a fantastic mount and if I can avoid having to replace it that would be preferable. Many thanks!
Cheers,
Gord

It can be done but I’d need the mount. PM me for more details.

Andrea

Jakub Korbel

Topic starter

2 days ago

Gordb · Sep 14, 2026, 12:32 AM
Hi,
I am just wondering if you had any success repairing your G53F mount? My mount is fine but the Pulsar 2 control unit has failed. The hand controller works. I am looking to either have the Pulsar 2 unit repaired or updated to OnStep. My understanding for converting to OnStep is that the motors and encoders will need to be replaced and some wiring as well. I don’t have the skills to do this and am hoping that there is the possibility of some help please? I actually have an OnStep controller built but it never worked properly. It was after that that I discovered that the motors, encoders and wiring needed to be changed. Any help would be greatly appreciated as this is a fantastic mount and if I can avoid having to replace it that would be preferable. Many thanks!
Cheers,
Gord

Hi Gord,

I purchased a new mount. I still have a broken G53f (gear failure). The Pulsar 2 unit should be functional. I can sell it to you if you are interested.

Jakub

Well written Respectful Concise