I’ve had a good look at link you sent me Bob and I think that I might have worked out the wire coil pairing in the old motor.
Pair 1: Black + Red
Pair 2: Brown + Yellow
Am I on the right track?
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Probably as good as any and better than most.
Cheers Bob
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Hi Robert
Wow…I didn’t realise “wishing” to get this globe working again would be such an intriguing and interesting project…I thought that i can just easily find the replacement part and just slot it in(then bob is your uncle)…pardon the pun Robert!!!
To be honest my soldering skills are next to nil so that can’t be an option for me.
But I think I can probably replace the crimps on the new motor wires ( if I can buy them somewhere), or if I can’t find buy ones I can try and use the old crimps instead.
At this stage and knowing what I know now, I’m rather nervous at using this new motor with the possibility of damaging the circuit board or doing any of other “irreplaceable damage”. Saying that I agree with you and would rather try and find the correct replacement motor (if possible).
I will have a thorough inspection of the yellow wire on the old motor and check for the obvious things you have mentioned and try it again and see how it goes.
If that doesn’t work then I will probably have no choice but to dismantle it and check for any internal visible faults. I will be extremely careful in the process.
I have a couple of questions please.
-
By dismantling the motor will we be able to have enough information to work out the correct gear ratio and revolution steps to find an exact replacement including the correct ohm resistance?
-
You mentioned above " the motor will rotate ok", ( is that clockwise or anticlockwise)???
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Based on the information on the circuit board are we correct to assume that the replacement motor should be 5 V?
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Will a 12 V motor have an ohm resistance similar to the old motor?
Thanks again Bob.
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Also, what do you mean by “Element 14” in your last paragraph?
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Good Morning Bob and All,
Exciting NEWS!!!
The motor is working again…
I took your advice and gave the wires (especially yellow) and the pins and everything else you suggested a good clean and tried the motor again and by some miracle it started working again!!!
I have attached a video and counted 44 steps for every full turn of the cog.
Does that mean anything and does it help in shedding any more light on the type of motor incase I need it in the future?
I will send another video of the working globe when I put it together again.
Thanks everyone for all your help and advice especially Bob.
Cheers
Peter
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Sorry, unable to send video because it’s too large???
Also one more thing Bob, the cog turns in an anticlockwise direction
Hey Peter,
You should be able to put that up on a cloud service such as dropbox or google drive (or unlisted on YouTube) and then share the link if it’s too large to put up directly on the forum.
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Hi Peter.
Good news for you and me. It was getting a bit difficult trying to trouble shoot remotely.
To answer some of your questions.
To even consider fixing this sort of thing this will HAVE TO BE an option. Find out all you can about it and have some practise. Also learn all about your new multimeter.
Without the correct tooling you will certainly make a mess of this, especially if you try to use pliers or something similar.
Good luck with that. In 40 plus years I never succeeded in doing this successfully without some sort of soldering involved. (refer above)
Questions:
- Counting the teeth in the gear box should give you the gear box ratio. You should be able to turn the motor and feel “steps”. This will tell the “steps per revolution” of the MOTOR. I just tried a couple and counted 24 steps for a 48 step (7.5º step) per rev motor which is a common figure. What you get by turning the cog would depend on the gear box ratio as well.
- Rotate OK means rotating correctly in the required direction. A stepper motor direction is changed by reversing the sequence of drive pulses to the coils. Actual direction does not matter as long as it is the right way.
3 & 4. I think steppers will operate over a wide voltage range. I think the quoted voltage is the maximum recommended. The coil resistance (Ω) allows you to calculate the DC current likely to be required at he voltage used. Bearing in mind that 2 coils may be energised at the same time.
This is a component supply company. World wide. Carries a HUGE inventory of name brands. Although they have a shop front in Chester Hill (Sydney) I believe these days a lot of business is on line. I think they deal a lot in large quantities but they will sell a one off. Postage costs become expensive at one off purchases but can be absorbed if purchasing several items. Type “Element 14” into your browser and sit back for a couple of days browsing the catalog.
Keep in mind you may have some sort of intermittent (the worst kind) of problem like a dry solder joint or something. If it fails again you at least have a starting point to investigate.
I feel this should be 48. This would indicate a 48 SPR motor and a gear box ratio of 2:1. Of course 44 could be correct and the gear box ratio slightly different to 2:1. At the end of the day it has to fit in with 1 revolution of the globe in 24hrs. Could be made for this specific purpose in which case you have a real replacement problem.
You could try dropbox but I don’t know how to go about this in the forum.
Does not matter as long it is the right direction. The direction is controlled with the driving sequence.
Cheers Bob
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Hi to all.
My first reply on 28/01
is incorrect. A 5 wire stepper can only be used as unipolar. It is the 6 wire stepper that can also be used as 4 wire bipolar by ignoring the 2 centre taps.
Cheers Bob
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Thanks Bob for your very comprehensive feedback and answers to my questions/curiosity!!
It was certainly a huge relief when the gear on the motor started turning and the humming noise stopped😁
It’s been a huge new learning experience for me in a space of a few days.
I counted the steps a few times and it’s definitely 44 steps per revolution and 60 steps per minute.
I thought I’d let you know incase they might be helpful.
The number of teeth on the black cog attached to the motor is 16 if that’s any help as well.
When I finish putting it back together I will check with the support team on the best way to upload the videos. The best view of the globe working and the cogs turning is in the night mode.
Thanks to all.
PS…instead of using the new motor i bought as paper weight, I’m planning to take it apart and have a good look and see how it’s put together just out of curiosity.
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Also I would like to thank Core Electronics for making having this forum concept because it has been very useful and educational to me.
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Thanks Peter,
I’ll let the rest of the team know, but a huge thanks to @Robert93820 here, it’s great to see such active community engagement. Have a great day guys!
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Nice work Bob and Peter! Well done on getting it sorted.
FYI, it is on the product description, though it’s buried in text rather than clearly provided:
I’ve added this to our list of improvements to make to the site.
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Don’t be too hasty. It may be my suspicious nature but I don’t get over confident when things just start up with no clear reason. Hence my reference above to possible “intermittent” problem.
However I hope I could be wrong and wish Peter well. That is quite a nice looking unit to have on display. Pity it seems to be no longer supported.
Cheers Bob
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Peter just sent through some youtube links to us to share here:
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Hi Support Team
When you have some time, I’m just wondering if someone could please explain to me how to calculate the “1/16.032” Reduction Gear Set quoted on the product description of the ADA858 motor on your website.
I have dismantled this motor I bought from you with the aim of trying to learn a bit more about the internal mechanics/coils/wire connections/common wire/ including the mathematical calculations.
I have tried to google it myself to do the calculations but I just can’t work out the 1/16 gearing calculation?
There are 5 gears inside.
Gear 1 with shaft - 24 teeth
Gear 2 (Pinion Gear) - 9 teeth
Gear 3 - 32 teeth
Gear 4 - 27 teeth
Gear 5 - 22 teeth
I’m also going to read up and get some soldering practice just incase this old motor stops again (as per warning from Bob) and I have to dismantle it for repairing myself or we can’t find a suitable replacement.
I’m attaching an image of the motor.
Thanks for your help
Peter
Hi Peter.
The gear box ratio is written wrong. Should read 16:1 or to be exact 16.032:1.
Simply means that for 1 revolution of the output shaft the motor does 16.032 revolutions or 16 if you want to be approximate.
The stepper itself is a basic 32 step per rev unit so to turn the shaft 1 rev requires 513 or to be exact 513.024 steps. 513 probably good enough for most purposes depending on the precision required. When designing something this error would have to be kept in mind. The error will compound and if the stepper turns far enough in the same direction what starts out to be a small error becomes noticeable. For instance with your globe it would be very hard to get the speed accurate enough to keep the globe rotating at 1 rev per 24hrs. The error would compound over time and would probably need resetting periodically.
Exactly 16:1 (512 steps/rev) would have been easier even if just because computer speak is in powers of 2.
Cheers Bob
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Don’t know if this answers your question but here goes.
The gear reduction is determined by the ratio between the number of teeth on the small and large sides off each gear. In your pic you can see this on the gear that drives the output shaft. the small side has 8 teeth the large side 32 (as far as I can tell). This is a 32 to 8 reduction or 4:1 ratio. The ratios of all gears then just add up. Possibly it equals 16.032:1.
This allows the motor to turn a number of times and the shaft moves a small amount. It adds torque and more accuracy. When the motor is told to step it turns 16 times but the shaft moves 1/32 of a rotation.
Note: The way stepping is preformed in this motor seems to be different than more powerful motors. (I think, still learning)
Cheers
Jim
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