Celestron CG-5 motor control board

[Astro-Geek]

My Celestron CG-5 advanced goto mount works well except for one niggling fault.

The Dec motor always runs at fast speed and can't be slowed down, (and therefore "runs away" on gotos).

I'm pretty sure it is a motor control board fault, because when I swap over the dec and ra plugs on it, the full speed fault switches to the ra motor, and the dec motor is then fully speed controllable via 1-8 keys on the handset.

I think I'm right in concluding that rules out all of the other possibilities, eg the dec motor itself, its wiring and plug, and all of the handset connections.

So it sounds like my motor board has partially failed, in that it does still control the dec motor back and forth, but can't vary its speed.

I was dissapointed to find that replacment Celestron motor boards seem to be much more expensive than other EQ5 goto systems, and also appear to be quite hard to obtain now, especially in the UK.

It's actually cheaper to buy a whole new EQ5 motor and controller setup, like the "enhanced system" with guide port and three tracking rates for about £110.  

The only trouble is that I would then never regain the goto functionality of the CG5 if the board could otherwise  be fixed.

Any ideas/thoughts/comments would be gratefully received.....

[lenscap]

Are you up for some DIY electronics? (Almost no soldering required.)

If so you could retain your motors/gears etc and make an Onstep goto controller with wifi using your mobile as a handset for less than £50.

https://groups.io/g/onstep/wiki/home

 

[Astro-Geek]

Wow.....

Thanks for that link.

(...and I'm a total sucker for electronics too.....) ?

I've skimmed through the links very quickly and it looks very promising if I've understood it correctly.

I really like the idea of getting into open-source solutions with DIY component level hardware.

I already have a vision of using my 6" Lenovo tablet as a super visual controller, rather than the two line text display of the ready-made offerings from SW, Celeston and Meade etc..

I was feeling quite depressed at the ripoff prices for the big company spares, wildly disproportionate to the original equipment cost.

One thing though, I haven't found any reference to my specific CG5 motors so far, which would really be the icing on the cake, saving me the cost of those.

[lenscap]

Since we know your motors & gear trains  are capable of tracking precision & usable goto slew rates they will be fine for Onstep.

You will need to find your worm & gear ratios & motor step angles & operating voltages but this info is readily available or easy to measure.

The Onstep Android app allows you to align & configure the system from a phone/tab and has lists of goto targets. You can also use it with an app like sky safari for planetarium style control.

I chose the cheap/easy Arduino option and no board or component cost more than a fiver (I used clones whenever possible) so if something eventually fails I will just plug in a replacement.

I've just built a system for my EQ3-2 but everything is configurable so if I upgrade to an EQ5 I'll just change the gear ratios in the software and it will drive that.

[Astro-Geek]

Excellent...

I'm still surfing around all the various sites and groups to decide what to buy and where from.

As my motors are fine, I guess I just need a wifi/bluetooth control unit on the scope to plug my motors into, and then I can access that via the Android app, (to get started).

Is there a UK specialist supplier for such a "box" ready-made ?

[lenscap]

I  don't know of anyone who sells a ready-made Onstep control box. You could make your own. eg;

Take an Arduino Mega 2560 or clone.

Plug in a Ramps 1.4 shield or clone.

Plug in two DRV8825 stepper drivers.

Connect a WeMos D1 Mini wifi module or clone. (4 soldered joints required.)

Connect your motors to the Ramps. You will have to fit new connectors.

Load the Onstep software. Configure it to suit your hardware.

Now you can control  the mount by wifi from a Windows laptop using Stellarium or Carte du Ciel etc or,

more conveniently, from an Android phone /tab using the Onstep app & Sky Safari plus or pro.

 

[Astro-Geek]

Thanks for your patience with me on this.

Your concise shopping list has made the project much clearer to me now.

Although I've "tinkered" with electronics for over 50 years, (right back to valves !), I never really looked into Arduinos or using them for projects.

I googled the items you listed, and even after just a  quick search on Amazon they came to under £40.

Up to then, I'd only found things like a ready made complete kit for an eq5 (with motors) at http://instein.eu/onstepeq5.htm

It looked very neat, but for the life of me I couldn't find any way to see the price of it or how to order it, even though that website did have a "shopping basket".

[Cosmic Geoff]

Sounds like an interesting project, but if you factor in the cost of your time I expect it would be cheaper to buy the Celestron spare part.  It's a sad fact of life that rarely required spares with one supplier are expensive because the makers can charge what they like.  Some people will pay up rather than scrap the unit.

[lenscap]

The Instein kit looks very professional. As the old Stella Artois ad used to say, it looks "Reassuringly Expensive"   ?

There is an email link at the end of their page. If you inquired they might quote you a price.

I have no idea if they sell the control box on its own.

instein.eu@gmail.com

 

[Astro-Geek]

I can appreciate that point of view Geoff, but I'm not sure it is a viable option, especially here in the UK.

My searches reveal the specific Celestron spare part as Item #: NXW432 , at $168, and I've not found anyone in the UK listing it.

If I am able to order it from the US, the carriage, customs duty, VAT and admin charge would bring it up to over $220.

It certainly seems like profiteering by Celestron, since the very similar but incompatible Skywatcher goto motor board is around $50, and readilly available here in the UK without incurring additional  import duty.

I'm also reluctant to invest that much when my Google searching revealed a great many other CG5 goto users who had exactly the same fault symptoms, runaway gotos and loss of speed control on the dec motor. There certainly sounds like some sort of weakness in the hardware.

 

[Astro-Geek]

Just now, lenscap said:

The Instein kit looks very professional. As the old Stella Artois ad used to say, it looks "Reassuringly Expensive"   ?

There is an email link at the end of their page. If you inquired they might quote you a price.

I have no idea if they sell the control box on its own.

instein.eu@gmail.com

 

Yes, it reminds me of adverts for stair lifts and tilting beds, the price is never mentioned, on the basis that if you have to ask you can't afford it !!

[Cosmic Geoff]

On ‎12‎/‎10‎/‎2018 at 15:26, Astro-Geek said:

It's actually cheaper to buy a whole new EQ5 motor and controller setup, like the "enhanced system" with guide port and three tracking rates for about £110.  

The only trouble is that I would then never regain the goto functionality of the CG5 if the board could otherwise  be fixed.

I understand that the EQ-5 and CG-5 are mechanically similar (I don't know to what extent).  If the EQ-5 drive motor kit fits on the CG-5, then presumably the EQ-5 GoTo upgrade kit will also fit.  I imagine the ~£300 cost might be a deterrent, though.

What's this?

https://www.ebay.co.uk/itm/EQDrive-UPGRADE-KIT-EQ-5-CG-5-MEADE-LXD-and-others-GOTO-telescope-control-system/222674984533?hash=item33d8769e55:g:qs4AAOSwI2xbWrjS:rk:13:pf:0

[lenscap]

9 minutes ago, Cosmic Geoff said:

What's this?

https://www.ebay.co.uk/itm/EQDrive-UPGRADE-KIT-EQ-5-CG-5-MEADE-LXD-and-others-GOTO-telescope-control-system/222674984533?hash=item33d8769e55:g:qs4AAOSwI2xbWrjS:rk:13:pf:0

That would work but when you add shipping & VAT ( and maybe customs duty ?) it would be around £300 as well.

[Astro-Geek]

4 hours ago, Cosmic Geoff said:

I understand that the EQ-5 and CG-5 are mechanically similar (I don't know to what extent).  If the EQ-5 drive motor kit fits on the CG-5, then presumably the EQ-5 GoTo upgrade kit will also fit.  I imagine the ~£300 cost might be a deterrent, though.

What's this?

https://www.ebay.co.uk/itm/EQDrive-UPGRADE-KIT-EQ-5-CG-5-MEADE-LXD-and-others-GOTO-telescope-control-system/222674984533?hash=item33d8769e55:g:qs4AAOSwI2xbWrjS:rk:13:pf:0

 

4 hours ago, lenscap said:

That would work but when you add shipping & VAT ( and maybe customs duty ?) it would be around £300 as well.

 

Yes indeed, the customs, value added tax, and admin charges for their collection really sting compared to just the shipping itself.

Yes, Ithe CG5 appears to have identical castings to the EQ5, so I've kept an eye open for any secondhand EQ5 gotos, but they rarely appear on their own.

The generic Chinese "enhanced controller" dual axis motor set is just over £100 new, and it's much more tempting than a £200 replacement Celestron motor board.

It has the standard three tracking speeds, variable speed slewing, and a guider port, but no goto without a PC.

The Arduiono option is going to take more time to setup, but it is much more versatile and future proof, and with much cheaper (highly competitive) interchangeable components and sub assemblies, one is not dreading the sudden death of a brand specific board or motor, costing hundreds of dollars/pounds.