Stepper motor just vibrates and gets hot

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Discussion Overview

The discussion revolves around troubleshooting a 5-wire unipolar stepper motor (J835L) that vibrates and overheats when powered. Participants explore potential issues related to timing and sequence in the control signals sent to the motor.

Discussion Character

  • Technical explanation, Debate/contested

Main Points Raised

  • One participant describes the motor's specifications and the control setup using a ULN2003A driver.
  • Another participant suggests that the delay of 0.1 ms between steps may be too short for proper operation.
  • A different participant raises the possibility that the stepping sequence might be incorrect, potentially causing the motor to reverse direction.
  • A later reply confirms that increasing the delay to 500 ms resolved the issue.

Areas of Agreement / Disagreement

Participants generally agree that the timing of the control signals is critical, with some suggesting that the original timing was too fast. However, there is no consensus on the exact cause of the initial problem beyond the timing adjustment.

Contextual Notes

The discussion does not clarify the exact nature of the stepping sequence or the implications of the motor's specifications on its operation.

Who May Find This Useful

Individuals working with stepper motors, particularly in robotics or automation projects, may find this discussion relevant.

neergmas
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I have a 5-wire unipolar J835L. I have not been able to find a data sheet on it, but I have found this diagram:

293yi5j.jpg


also, the motor has the following information printed on its label:

Uni-Polar, Bi-Filar
120 Ohms
7.5° per step or 48 full steps per revolution
JARL J835L PM 24P

I have connected a ULN2003A ("focus.ti.com/lit/ds/symlink/uln2003a.pdf"[/URL]) between my uC and the motor like this:

[ATTACH=full]130959[/ATTACH]

where:
B = blue wire
P = purple wire
Y = yellow wire
O = orange wire
W = white wire

I have tried driving the circuit in these two orders:

Step POBY and PYBO
1 1000 1000
2 0100 0100
3 0010 0010
4 0001 0001
5 1000 1000
. . .
. . .

Where 1 has been verified to be 10v and 0 is 0v. I set each step and then wait for .1ms. The motor then just vibrates. Can anyone give me a pointer?

Thanks!
Sam
 

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That delay of 0.1 mS seems too fast.

Just for a test, try 500 mS.
 
Could be a problem with timings or the run sequence. It could be going forward, then next step makes it go backwards.
 
vk6kro said:
That delay of 0.1 mS seems too fast.

Just for a test, try 500 mS.

That was it! Thank you :)
 

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