I found this motor and can't find info or specs about it online. Copal MIS-3 synchronous motor, 1 rpm, AC, four leads.

I did find one diagram online that looks possibly similar (shown below), but not sure.

What size and type of capacitor is needed? .22ufd non-polar poly 400V?

I'm wondering- is the rated 1 rpm before or after considering the gear train that is attached? I realize it is not a stepper or servo motor, but can I control simple off/on using a microcontroller?

 

It will be synchronous to the applied mains frequency.
The 1RPM I would guess is before any external gearing, just internal gearing.
.
Some do not require a capacitor , measure the resistance between the 3 cond.

 

By a look on the site, most of their synchronous motors are AC stepper motor principal as used by Slo-Syn of the 60's to 80's
If so, Capacitor required.

 

Thanks!

Resistance measurements:
Green/Ground -> Black = 5.5K
Green/Ground -> Red = open
Green/Ground -> Blue = open
Red -> Blue -> 5.4K

So my diagram above appears correct?

Your recommendation for a capacitor?

 

The green wire should read open to the other three, and the blue wire resistance to both red and black should be similar. It may be that the color coding is incorrect, as green or green/yellow, is designated as common to the frame by common standards.
Red to black resistance should be about 10 K ohms.
If you have 120 volt mains then I suggest connecting between black and blue, with a capacitor, or capacitors in parallel adding up to 1 mFD, and rated for at least 200 volts, between red and black wires. If the motor does not appear to turn, quickly remove the power. Next try it with those connections the same, but also connecting the green wire to the blue wire. At this point you might have mains voltage on the motor frame when the power is on, so do not touch the frame.

 

Thank you MisterBill2!

None of the four leads are electrically connected to the motor housing, by VOM testing. Black to red is open, as are all other combinations not mentioned above.

Thanks for your suggestions and warning, I will get back to the forum next week when I am back in town and have time to play with it more. Yes, I will be using 120V mains.

Maybe I should mention- the external gearing is designed to allow CW rotation only. I have not tired to dismantle it (yet).

 

Here is the Slo-Syn model.

 

But... mine has four leads, and none of the leads are tied to the case.. ?

 

They should not be connected to the frame.
Except the Green if it is earth conductor.

 

Drop Nicon Copal an email with picture !!

 

It could possibly be that the motor is wired with separate connections to both windings, rather than a common, for some reason. if that is the case then connecting green and blue should allow it to run, with a capacitor between red and black.

 

I tried several different setups (using three .33mfd 400V non-polar caps in parallel):

1) cap between Red and Black
Green to earth ground
AC between either Red or Black and Blue
2) cap between Red and Black
Green and Blue tied together
AC again between either Red or Black and the Green/Blue combo
3) cap between Blue and Black
Green and Red tied together
AC between either Blue or Black and Red

In all three cases I get a hum but no movement, so I immediately disconnect.

So... what's going on here? Could the cap not be the correct value to get it started? I can turn the gears with my hand so it is not frozen.

 

OK, it may be that my estimate of the required capacitance was low. It may also be, if that 87115 isa date code, that the lubricant has solidified in the gearbox. Most likely is that my capacitance estimate is low. You could tryb adding more capacitors in parallel.

Setup #2 is what i would expect to work.

How did you verify that the motor was not turning? I see a sight window in the center of the back.
Another question: this appears to be a used motor, what was the original application? It may possibly be worn out.

 

Thanks once again! You are right... I had not looked closely and after removing the external gearing I can now see and feel that the motor shaft is frozen tight. Out of curiosity I would like to free it, but I don't see any way to open the casing without destroying it. I found it at a thrift shop, so I have no idea of its intended application.

 

Often due to a high rate of wear, they are pretty much non-repairable. Gear wear etc.

 

For a frozen shaft in a sleeve bearing like that, Kroil or Cyclo Breakaway are two penetrants that may free it up. OR, if you can find it, Just a few drops and let them flow into the gap along the shaft. After a few minutes then grab the shaft with pliers and very gently try to rotate it a very small amount.
To lubricate the other portion, peel off that clear window in tthe center of the label and squirt some Kroil in there. Or just a dozen or more drops of light oil, but not penetrating oil, because part of that evaporates. Usually the failure is the lubrication. But not always.

 

Just to post back: I soaked the motor in Rosonol for a few days, usually that will dissolve old grease. But still the shaft would not budge. So I decided to destructively dismantle it just to see what was inside. I don't generally like to destroy things but sometimes I can learn from seeing how things are made.

I think what might have happened is the gear assembly inside the motor was damaged/misaligned so that the gear teeth were caught against each other.

I find it interesting that there was two separate coils with no common. Below is a photo of the one with green and black leads.

This motor did not cost me anything and did not work, but I did learn several things from you guys, thanks very much!

 

I figured as much (post#15).