Is it possible to convert an eq3-2 drive to an eq5 drive?

[SteveBz]

Hi People,

I have an old unmotorised CG5 that I'm trying to get working (both axes are totally seized).  At the moment it's resisting all my best efforts, but I hope that will soon change.

Assuming the best, I also have an unused eq3-2 motor drive.  Would it be possible to convert the eq3 drive to an eq5 drive by changing the brass cogs on the motors?  The handsets look identical.

What do you think?

Regards,

Steve.

[ronin]

Will start by issuing a disclaimer - I could be 100% wrong - but a distant memory says that the RA+Dec motor upgrades packets (about £100) were in 2 flavours. One for the HEQ5 and one for both the EQ5 and EQ3-2.

In effect the EQ5 and the EQ3-2 addons were the same. Just have this idea that they were advertised as "Upgrade for EQ5/EQ3-2 mounts".

I am sure they were advertised as such, but it would have been easily 18 months ago likely more. Cannot find any site that says or implies this now, they all have the EQ3-2 and the EQ5 listed as seperate items. Have only looked at 2 however, FLO and TS.

Suppose the best way to put it is: I cannot say that they are the same but I would not be surprised if they were identical and so compatible without modification.

Better wait for another opinion, someone may well hafve bought the upgrade package in the past and can recall similar or otherwise to me. But I am sure that there was just 2 options and one therefore did 2 of the mounts and it would not be the HEQ5 and EQ5 that were the same.

[SteveBz]

When things are working, I could just try it and see.  When I put the EQ3 RA motor on an EQ1 the difference in tracking speed was very obvious.

[JamesF]

The EQ3-2 and EQ5 have different gear ratios internally which means they need driving at different rates.

I believe that  the motor sets for each mount are identical with (from memory) a 120:1 reduction on the gearbox hidden inside the motor body.  I think the difference in  drive rate is achieved by programming the microprocessor inside the handset differently, so the pulse rate to the step the motors is different.

I'd suggest therefore that it's not going to work very easily.

What you might be able to do with a certain amount of fiddling about is move the motor mounting and put a set of belt-driven gears between the motor gearbox output shaft and the mount drive input shaft to achieve the necessary change in drive ratio, but by the time you've done that it's probably a world less pain to buy a set of EQ5 motors.

James

[SteveBz]

Maybe I should just sell the eq3 motor and use the proceeds to buy the eq5 one.

[JamesF]

That may well be the simplest solution to be honest.

James

[SteveBz]

Update from 365astronomy which you might be interested in:

"You asked us a question regarding EQ5 handsets.

We have now received a reply from the main supplier of this item and he has confirmed that the EQ3 & EQ5 handsets are identical.

Hope that helps

Regards

John Bush

365 Astronomy Advisor"

 

[JamesF]

Hmmm.  I think we'd best be sure we're all talking about the same handsets.

The ones I have in mind are the ones that come with this drive for the EQ3-2

The handsets are labelled "EQ3-2" and "EQ5" as far as I'm aware, which suggests they are not interchangeable.  Unless of course more recent motor sets have changed.

James

[SteveBz]

It's the black handset and not the red one. Mine is labeled eq3 on the back.  Interesting.

[JamesF]

Yes, the black one is the one I have in mind.

James

[steviebee]

I was going to ask the same question but in reverse. I have a motorised EQ5 mount which I am going to upgrade to synscan. I also have a EQ3-2 with seized motors. I was just going to try the EQ5 motors on the EQ3-2 and see, but that wont be until October, sorry!

[SteveBz]

1 hour ago, steviebee said:

I was going to ask the same question but in reverse. I have a motorised EQ5 mount which I am going to upgrade to synscan. I also have a EQ3-2 with seized motors. I was just going to try the EQ5 motors on the EQ3-2 and see, but that wont be until October, sorry!

Hi Stevie,

I have a pair of unused boxed eq3-2 motors that I'd swap for your eq5 motors if you like?

Let me know,

Tx

Steve

[JamesF]

I think you will need to have a handset that you know works with the mount as well as the motors.

James

[SteveBz]

16 minutes ago, JamesF said:

I think you will need to have a handset that you know works with the mount as well as the motors.

James

Sorry, to be clear I'm offering the eq3 h/s and motors and all the bits and pieces in exchange for a full set for eq5.

[steviebee]

1 hour ago, SteveBz said:

Sorry, to be clear I'm offering the eq3 h/s and motors and all the bits and pieces in exchange for a full set for eq5.

Hi Steve, mine are almost new (with haqndset) with very little use.. Only trouble is they are in France at the moment and I will not be over there until November. I wont be back until December. I will get back to you nearer the time if that is ok. Obviously if you have another offer in the meantime you must go for it.

 

Regards.

Steve.

[SteveBz]

That sounds great. Do you get dark skies in France?

If I haven't got another offer by then, drop me a line.

Have a good day.

[SteveBz]

6 minutes ago, SteveBz said:

That sounds great. Do you get dark skies in France?

If I haven't got another offer by then, drop me a line.

Have a good day.

 

48 minutes ago, steviebee said:

Hi Steve, mine are almost new (with haqndset) with very little use.. Only trouble is they are in France at the moment and I will not be over there until November. I wont be back until December. I will get back to you nearer the time if that is ok. Obviously if you have another offer in the meantime you must go for it.

 

Regards.

Steve.

In fact if you're going viewing I'll strap it all to the roof rack and follow you over.

If you have a field there we could have a sgl stargazing event! ?

Ok. I'm getting ahead of myself. Just the motor kit would be great.

[steviebee]

42 minutes ago, SteveBz said:

That sounds great. Do you get dark skies in France?

If I haven't got another offer by then, drop me a line.

Have a good day.

32 minutes ago, SteveBz said:

 

In fact if you're going viewing I'll strap it all to the roof rack and follow you over.

If you have a field there we could have a sgl stargazing event! ?

Ok. I'm getting ahead of myself. Just the motor kit would be great.

32 minutes ago, SteveBz said:

 

In fact if you're going viewing I'll strap it all to the roof rack and follow you over.

If you have a field there we could have a sgl stargazing event! ?

Ok. I'm getting ahead of myself. Just the motor kit would be great.

Yes Steve, very dark skies. I think there are about 4 street lights in our village. The nearest one about 150mtrs away. We cant see the others.we have a big garden, so plenty of room for a SGL star party :-D. I have a great 360* view and will be putting my (home made) Observatory at the bottom of our garden once the Mayor gives the ok. I will drop you a line when we are back.

regards.

Steve.

[SteveBz]

Hi Guys,

I've just taken my EQ3 handset apart and here are some photos.  It doesn't seem very obvious that there would be a simple way of switching between models at the production level, so I feel that probably all handsets are the same.  The supplier also confirms that all handsets are the same, so I think that any differences would probably be in the gearing.

Could anyone post some photos of EQ5 gears.  I'm about to post some photos of the gears in the next post.

Regards

Steve.

[SteveBz]

Here are the photos of the gears.  I'd love to see photos of any EQ5 gears that you have.

Regards

Steve.

[JamesF]

I still think the handsets are different otherwise they wouldn't bother to label them.  I suspect that large chip in the middle the photo of the main circuit board is a microprocessor which controls the stepping rate of the motors and has different parameters for the stepping rate for each mount.  So the process for making up a handset would be the same for both except for inserting the relevant microprocessor.  I assume that's why it is the only component on the board that is in a socket -- it means the handsets can be configured to match demand.

But I could be completely wrong

James

[SteveBz]

I've just Googled it.  Apparently it is a MCS-51 microcontroller (https://en.wikipedia.org/wiki/Intel_MCS-51)

So you are right, it could be programmed differently for each mount.

Has anyone tried swapping over handsets?

I once tried it on an EQ1 mount, the slewing worked but the tracking lost ground against the sky.

Steve.

[SteveBz]

And here's an update:

If I manually turn both RA slo-mo controls through 6 rotations, the mounts both turn equally turn through about 1hr 10mins of RA

If I manually turn both dec slo-mo controls through 4 rotations, EQ3 mount turns through about 22 degrees of dec but the CG5 turns through about 10 degrees of dec (it may even be 11).  It looks as though the CG5

It looks as though if I mounted the drives I'd get tracking in RA, but dec would slew at double speed.  I don't know how much that even matters unless I implement GOTO.

The electronics look very old-fashioned.  I think they just keep making them and then change the gear mechanism between EQ versions.

I think my next experiment is going to be testing it.

What do you think?

Regards

Steve.

[SteveBz]

Hi Guys,

Ok, I spent most of Friday and Saturday messing about with these motors.  I'm pretty much convinced that there is no difference between the motors or the handsets between models.  The only difference is the gearing ratios and the fitting screws/brackets and here's my reasoning.

1) If you look at photos on the internet of the gears, for RA they are either straight though flexi-couplers or 1:1 brass gears for all models.  For dec they are the same for EQ5 but about 2:1 on the EQ3. 

2) I see no reason to vary the gears for dec (but not for RA) AND also vary the the handset programming.  It is unnecessary, in fact it would be cheaper to reprogramme  the microcontroller in the handset and keep all the gears the same.  I suspect that mount manufacturers have kept the gearing for RA constant across both models for the same reason - why make it different when you can streamline your manufacturing costs?

3) The electronics in the handset is all very dated - circa 1980.  It looks unmaintained and I suspect everyone with the skills to reprogramme it has long since retired or moved on, therefore the manufacturers have to treat it as a black box and only vary the gears.  This is why the handset is the same across both models.  The new model (the red one), which I don't have access to, claims it is backwards compatible, so I suspect this too is identical across both models.

However the mounting for each is very different and I didn't feel I could fit the EQ3 model on my EQ5 without a lot of compromises or a bench lathe and a professional compressor-driven paint system,  so that seems to me to be the main reason for the different models.

For this reason only, I'm throwing in the towel and going to swap out my EQ3-2 motor drive and handset.  When I do get the EQ5 set, I have a second, older, driven EQ3 mount.  I'll switch them and test my theory.

Thanks for reading,

Steve.

[ronin]

The software is potentially different but not sure, there is/was someone that redid the software and made their own controller up. They made it run at different speeds so it would get from A to B quicker. I think the big problem was getting the software on to the PIC chip.

Not sure if this was it: http://telescope.marford.me.uk/Projects/PICcontroller.htm

The link I had was a different address, but it looks similar.

I have often thought that with the motors that a Raspberry Pi might be an option as the controller. Do not have any real knowledge of the Pi but from a very very brief look it almost seems an option. Using the link and the diagram above could a Pi be used in place of the PIC16G627's to tell the L193D's to pulse.

Something to contemplate on those rare cloudy nights we get, and observing is not possible.