stepper motor help

[realolman]

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I would like to operate a component of a machine that contains a stepper motor on the test bench, for the puposes of adjustment and repair. I feel sure the OEM would frown upon this activity, so I don't think I could get much help from them.

I have an Oriental brand bipolar stepper motor with 4.5 ohms per winding. It is connected to a Sanken A2918SW motor driver. If anyone is interested the documentation is at :

stepper motor documentation

There is not as much info on this model as others. I have disconnected the stepper driver board from the rest of the component, and am enabling and phasing it with a BASIC STAMP according to the truth table on the documentation. I think I have the sequence correct because I have tried all the combinations I can think of and this one seems to be the best.

The problem is it doesn't seem to have as much torque as it should.

VBB > Vref = 39VDC, and I am using enable ,1 enable 2, and phase 1, and phase 2 . It seems to me from looking at this drawing that I should have something hooked to E1 and E2, but I don't ... should I have something hooked to E1 and E2...any suggestions on the resistor values?

thanks

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[TonyNo]

You need Rs to complete the H-bridge circuit.

Maybe try a 1 ohm/2W+ resistor.

 

[realolman]

You need Rs to complete the H-bridge circuit.

Maybe try a 1 ohm/2W+ resistor.

Thank you.
The diagram shows that going to ground... I suppose that means you would connect it to V ref.
Do you think any of the "sense" stuff needs to be connected?

 

[TonyNo]

Is Vref your negative supply lead (DC common)?

You likely should have the sense connected, but it may just be for current fold-back. It's been a good while since I worked with steppers. I was not able to find any app notes on that device, though.

 

[realolman]

Is Vref your negative supply lead (DC common)?

You likely should have the sense connected, but it may just be for current fold-back. It's been a good while since I worked with steppers. I was not able to find any app notes on that device, though.

Thanks for your reply

Yes, Vref is the 39 vdc common

I was hoping the sense was just for some sort of over current fold back.

Even the company data sheet has much less info on this than the other models.

 

[TonyNo]

Go ahead and try that resistor without the additional R/C.

 

[realolman]

Go ahead and try that resistor without the additional R/C.

Thank you, I will.

I found a better datasheet. Much more info. I think it will help a lot.

Thanks to all who replied. I reallly apreciate it.