Saving an old mount.

[xelasnave]

I have a Meade lxd 55 goto mount and a dud paddle.
I sneaked it into a repair job with other "normal" items for repair with a guy who fixes tvs.
I dont hold much hope of repair and I wont buy another if indeed you can find one...however my thought is..wire the motor direct with a "volume" control"☺ er potentcheometer I think however its spelt☺ such that I can dial in the ra to track ...polar aligned well would see this unit, with the dec assembly removed and a fitting to hold the camera a handy thing... I made one with another mount which is not goto but am having motor problem due to its hand paddle...a pre goto sold as a eq5 ... way before the newer ones...
Anyways can I do what seems like a possibility.
Alex

[xelasnave]

Here is the one that I am working on, not the meade, but you can get the idea of removing the dec assembly...the camera moves thru dec and fixed for the target. Neither mount was flash but should by ok for wide field.
I like wide field and it would be nice to have something like this running while you are out there for a specific yarget with the main scope...or for those nights where you dont feel like a long set up as hopefully it will handle up to 200 mm fl...and I am making another bracket so I can mount two dslrs...anyways it would be nice to get them functional.
Alex

[bojan]

Alex, not likely :-)

Motors are steppers and they can't be wired to "volume control pot" just like that...

If your friend can't help, I may be able to.

[xelasnave]

The above mount I pulled down ..even the gear box on the motor and cleaned it lub with olive oil and it is rather reasonable so far.
Alex

[bojan]

You need something like this (http://www.iceinspace.com.au/forum/showthread.php?t=45079&highlight=mount+wide)...

[bojan]

Surely not olive oil????
Use green Lithium grease for that.

[xelasnave]

Thanks Bojan.
He is also looking at the paddle for the non goto.
It seems to me that the problem is with the on/off switch....ot ran for hours but when I yried later I had to jiggle the switch until finally no responce..I was going to solder the switch out by putting a wire on the board side...and use the power plig as switch on..it only has to run in ra...one speed..no need for controls.
Thanks again.
Ot will be interesting to see if this guy can fix it...I am hopeful of using this set up on m31. ...30 second captures approaxh.
Alex

[xelasnave]

Yes. Great you know what I am about.
It is a shame that these mounts sit around and two cameras...if I can combine images from the old canon and the new nukon I will have two eyes in my draggon fly.
Should buy that modded cam and dedicate it to ha...
Alex

[xelasnave]

Yes but I cant find it...however it will do the job until next pull down.
I like using oil over grease anyways.
Alex

[RyanJones]

I'm going to add to this because one thing that generally frustrates me is when people say that things can't be done but not why. ( no disrespect intended Bojan )

They use stepper motors because they require a given number of pulses to complete a rotation. These pulses can then be measured over time to give a correct slew rate. A potentiometer ( volume control ) is effectively a variable resistor. For this to stay accurate you would need to supply the exact same voltage and current and have no change in the load on the motor. Almost impossible to do accurately enough without a whole lot of extra electronics.

Good luck with the resurrection of the mount Alex

[bojan]

Alex and I are good mates for a long time (I hope this feeling is reciprocated).... so I felt I do not have go too deep into technicalities at this instance, instead I offered direct hands-on help with this.
I even have spare electronic circuits (the same as described in the link I provided (http://www.iceinspace.com.au/forum/showthread.php?t=45079&highlight=mount+wide)), which I can give him (gratis of course) if he chooses to accept my offer.

So.... no worries.

[RyanJones]

I totally understand Bojan and as I said, I was in no way being disrespectful. I just think it is handy for anybody else reading the threads to be able to understand why. I'm sorry if I have butted in where I shouldn't have but I guess this is just the first thread where I've voiced this opinion.

[xelasnave]

Thanks Ryan.
I thought what you said would be the case as I figured these circuits were there for a reason.

I think you may be able to do it with a volume control but you would have to in effect manually guide it...which is a pain and not easy to get right...but Bojan has my back I am happy and grateful to say.
First I wiat to see what if anything can be fixed ..it only need one mount..each requure a different approach and will cross that bridge when I come to it.

But I really have been thinking of adding at least the second camera as I went outcearlier and the trees are closing me out here I think less than an hour on a target☺
Alex

[xelasnave]

Yes mates and yet to have that beer.
The experience had me actually looking at the circuit and yrying to work out what was going on...I was almost going to try and replace the switch that required soldering ... something I once did on big stuff ...new to new relatively...learning new stuff...
And you wont believe..I purchased a little dingy which I am converting to a camper sailer to keep busy☺
Alex

[Paullus]

Hi Alex,

I've had a slightly similar issue with my LXD75. A few years after purchase the motors clapped out (probably the circuitry more likely). Long story short I purchased a Skywatcher EQ5 dual axis drive kit (no goto) for just under $250 AUD at the time from 365Astronomy. You're probably looking for a cheaper fix but this is a viable option to consider. I used it for the first time last month on Fraser Is with guiding for widefield; worked well.

If you're interested I have the LXD75 motor units and the directional controller/paddle sitting a box taking up space. The motor units I wouldn't trust (no/uncontrollable slewing at times) but the paddle should be ok. PM me if you'd like me to send any/all of it your way.

Cheers

[xelasnave]

Thanks I really appreciate your post and kind offer.
First step is to determine if the fix it guy can fix it.
He hasnt rung and I will give him a littlevmore time before I ask if he has looked at it...anyways its cooking ... have to wait for the next decision gate.

I sure appreciate everyones input..I dont feel like its a problem now but just something that will become useful with a little more effort.
The prospect of using this set up for two or more cameras has really had me thinking given there is a program that can marry photos from different cameras...what was it ? Must get it and try it out.
Alex

[xelasnave]

Well its back.
He claimed that he fixed it but I think I have paid $40 for the priveldge of being conned as it does not seem to work....in fact I very much doubt he even opened it.
I was going to go back but I think I would be in for more of the same.
The loss has been taken and I wont add getting upset or worse by going back.

I have decided not to worry about the Meade mount.

However Bojan I plan to send you a PM to investigate what could be done.☺
I put a photo here as I dont think pms carry photos.
Alex

[bojan]

Hi Alex,

Yes, by all means please do - just post it to me.

I will try to fix it for you (of course, depending on root cause of problem and availabity of parts - and gratis as I mentoined earlier).

[bojan]

Alex,

After very careful look at your handpad, I have not so good news for you - it is the processor that behaves erratically, upon power-up sometimes it starts properly but more often it doesn't - usually it just hangs, which (again sometimes) results in high current (basically short) through stepper driver transistors. I checked the reset circuit (which was my prime supect after initial look) but it works OK, all supply voltages are OK... so basically that's it.
(This handpaddle has no protection from overvoltage - no voltage regulator - so theoretically processor could be damaged by applying higher (12V) voltage... any chance of that happening in the past?)

Motor you send me is OK.

My next step with this will be to try to read processor's firmware and program the new one (I have couple of them from previous projects), but I don't put much hope in the positive outcome of this as it may be unreadable due to damage and besides, usually processors are protected from reading by manufacturer, in which case the only way would be to find the same hand paddle with working processor as replacement.

I may have another solution for you as well - I was planning to totally overhaul my LXD75 (new electronics, new motors), so I will be ending with surplus of those.
I haven't finished that 100% yet (as is visible here (http://www.iceinspace.com.au/forum/showpost.php?p=1227000&postcount=6), I am still using the same hand paddle with processor clock multiplied by 5 to match the added belt transmission) but reversing the mods back to original and giving it to you would promt me to fully implement OnSTEP controller, new motors etc. However it may take me some time to undo the mods.

Another option for you would be to do the same, of course. Again, it will take time.

So.. let me know your thoughts :question:

[xelasnave]

Well first of all thanks for looking at it Bojan.
Although its possible I connected 12 vlt I doubt it.
It sounds as though it really is not worth the effort you need to put in.
Perhaps set it aside and we can think about it but all I can see at this stage is to throw out the box and you keep the motor for one of your projects.
Alex

[bojan]

Alex,

I do not give up that easily.. and I have too many surplus motors already from mods I did in the past ;-)
So, lets see what happens, I intend to finish this - it is the personal challenge now :-)

[xelasnave]

I like your spirit but please do not let it come before things that are more important for you or more particularly that may be more important as far as your good wife is concerned.
Alex

[bojan]

Alex, I just checked, your LXD-55 has the same worm gear as my LXD-75..
which means my old controller (when un-modded) should be suitable for your mount (unless motor gearboxes are different), with some re-wiring.

Also, do you need buttons? Do you need DEC drive?
If not, with a little tinkering I can assemble simple electronics (only tracking) for you from parts I have in my drawers.

[xelasnave]

ĢHi Bojan
What you have is not anything to do with a Meade unit, although I do have a LXD 55 that has a dud hand box.
I dont know what brand ot is but I guess you could say Celestron because it came with a 150 mm refractor that is a Celestron.
All I need is RA drive as the dec has been removed and replaced with a ply unit to mount the camera and dec adjustment is simply down to moving the camera to the target object and screwing the base mounting screw to hold the camera at the appropriate angle.
As it is for wide field with short exposure so dec tracking is not required.
There is a photo earlier here showing the idea.
So all it has to do is turn at the appropriate speed on RA. Dec is fixed or rather removed (see photo)
I figure with good PA and short exposure the unit should be great for wide field.
The photo above shows a one camera ply mounting unit but I have since made one that holds two cameras...which I cant photograph as it is in Sydney...but it is just a box sortta thing.
I took the dec off to reduce weight and make the unit easy to manage.
I dont need buttons or even an on off switch as the power can be cut off when I take the clips off the battery.
Alex

[xelasnave]

Here is the photo adjusted to see it clearer.
Alex

[xelasnave]

The shiney metalic thing on the ply box is the mount for yhe Polemaster camera...the blobs are blue tack☺
Alex

[bojan]

Excellent.
Just check for me the number of teeth on your worm gear (you can do it by turning worm by hand and count the turns needed for RA axis to make 360°.

[xelasnave]

I wont be able to do that until around 10/12 as it is in Sydney and I am at Tabby for a while...
You should see the dust here ..really strange...
Alex

[bojan]

OK.
Some time ago I made electronics for my EQ3, it fitted inside DEC compartment next to counterweight shaft, see attached image.

I am still missing timing pulleys (1:4, with 48, 12 teeth (http://www.iceinspace.com.au/forum/attachment_browse.php?a=57883) or some other suitable combination) for T2 belt (which I have) transmission, so I will simply print them with 3D printer, this should be OK for wide fields. Hopefully the larger one will fit to your mount, and you will be able to fix the motor with suitable bracket.

If your mount has 144 teeth worm, I do not have to change firmware for Motorola processor used here.
It is certainly possible to do the same thing with one of small Arduino or digispark processors (plus stepper driver board), but this is almost ready and tested, so....

[xelasnave]

Thank you Bojan.
Alex

[bojan]

If you are not happy with printed pulleys, you can always go to ebay and get them from there.
60 teeth (https://www.ebay.com.au/itm/GT2-Timing-Belt-Pulley-Aluminum-8mm-Bore-60-Teeth-for-RepRap-3D-printer-NT/202497763191?_trkparms=aid%3D555018 %26algo%3DPL.SIM%26ao%3D1%26asc%3D5 2547%26meid%3Db93bba9260354215ae188 5daee697b4c%26pid%3D100005%26rk%3D1 %26rkt%3D12%26sd%3D273059203809%26i tm%3D202497763191&_trksid=p2047675.c100005.m1851)
or here (https://www.ebay.com.au/itm/Timing-Belt-Pulley-XL-10T-100T-Synchronous-Wheel-Selectable-Bore-For-3D-Printer/273059203809?hash=item3f9398cae1:rk :1:pf:0&var)for more variety.

[bojan]

Here you go.... 60 teeth timing pulley, it fits pretty good to belt (subject to star test of course).
I found metal one for motor +(15T) so 1:4 transmission is now complete.
Now I'm just waiting for your confirmation on worm gear number of teeth (I am fairly confident it will turn out to be 144) and I have to sort out that Sharp laptop (to be able to program the processor for stepper driver).

[xelasnave]

Thanks Bojan but please you worry me that you are going to so much trouble.
As I mentioned I cant provide information re the worm gears until I return to Sydney...
Thanks again for your attention.
Alex

[xelasnave]

I favour function over form ... it can be made of cardboard if it does the job...
Alex

[bojan]

Quite...
But it is also a matter of accuracy - so if you find an uneven tracking rate, you should replace this pulley with more precise one.
And it is not a trouble, really... I am doing a bit of experimentation for myself, so this is a good excuse :P
As for 144 teeth or not, let's wait till you are back.

[Wavytone]

Hi Bojan,

If it all gets too complex I’ll suggest there is a simpler solution along the lines of a controller I made in the 1980s using just two CMOS ICs and a handful of components that fitted in a tiny box. You can solder it on a prototyping board (hard way IMHO) or use wirewrap, this is quick and easy.

In essence ... wire up a CMOS 7555 timer with RC components and a pot as Alex suggested to give a nominal tracking rate variable by +/- 50% and feed that into the STEP input of a stepping motor controller chip. Wire to motor and power supply with a diode for reverse voltage protection and a fuse in it in case something is shorted. For the variable resistor use a decent Bourne wire-wound 10-turn type, not the rubbish from Jaycar as these fail rapidly.

You can add some hardwired logic for fast/slow push button from a handset if so desired.

The RC circuit will be good enough for visual since there’s no attempt to correct for PE or add autoguider inputs (which are feasible BTW).

[bojan]

Hi Nick,

Yes, I am fully aware of simpler solutions (I was using Signetics 555 timer in exactly the same configuration and for the same purpose back in '80es), but now this is simpler for me because I already have the circuit (actually, couple of PCB's) from before.
Also, my firmware accepts input from buttons for tracking corrections so... here you go.

[bojan]

I tried to read processor (Hynix GMS97L51), no luck - my Willar programmer does not have this processor on the list, and for any other C51 it says "ID error".
Funny thing - "L" in GMS97L51 means it is low-voltage version, so it is not supposed to work at supply voltage above 3.6V.. and it is on 5V in Dual Axis controller !!
Very strange - but I am not surprised after my experience with my Dual axis controller that came with my LXD-75 (I wrote about this saga (http://www.iceinspace.com.au/forum/showpost.php?p=1227000&postcount=6) couple of years ago).
Anyway... unless I obtain the hex listing for this paddle (so I can program the new processor), it will have to go into storage to wait there for better times....