where's the motor controller for this stepper?

Hi, I’m tearing down an HP710c for parts and its got a nice little stepper in it that I’d like to use in a solar tracker project I’m planning. I’ve read that the motor controller that drives the stepper should be kept too. My problem is that I don’t know what they look like (I’m that noob). Can someone give me a pointer?

Is it this circuit board on the motor where the wires connect?

(I’ve realised that you can’t really see the circuitboard in this shot so I’ll try and upload another tomorrow).

If that’s not it the controller must be on the main board of the printer. The wires from the stepper run to the white connector at bottom right in this picture:

Sorry for the crap photos, my camera died so I had to take them with my phone. Thanks in advance for any replies. :slight_smile:

M35S1N and M35SP , probably two different species. Why do you think it's stepper?

Magician: M35S1N and M35SP , probably two different species. Why do you think it's stepper?

I don't even have it in my hand, and I'm pretty sure its a stepper (an el-cheapo stepper, though, to be sure).

scary, I would forget about trying to find the driver for this stepper; its likely on the board - in fact, I'm not sure (I haven't looked it up), but it may be that Siemens IC to the right of the larger IC on your pic (that IC is likely the controller IC for the printer - since it is marked HP); then again, it may be a controller intergrated into that main controller IC, which I doubt would be useful at all. You might want to look up some of those IC numbers, but in all likelyhood, just cut the wire, ohm-out the coils so you know what wire goes where, then work on obtaining/building your own driver (likely an L293 or L298 will work fine - if you can find the exact spec sheet for the stepper, that will help).

Hi

I have just salvaged a stepper from a HP printer (I don't remeber the type number)

It looks much like the one you have, and the PCB are almost identical.

If I'm right you have 5 wires comming from the motors just like mine, which is a unipolar motor. I made it go via a ULN2003

I found the spec here:

http://www.nmbtc.com/motors/part-numbers/Permanent-Magnet-Stepper?data%5Bpg%5D=10&data%5B147%21%5D=&data%5B148%21%5D=&data%5B149%21%5D=

Ernst

Hello everyone, thanks for your replies, particularly cr0sh. I’ll give up on the controller then and just see if I can buy one. The specs for this particular motor are here, which I found from a U-toob video of the motor being run by an Arduino with a DIY controller. I can’t seem to embed the link for the video but if you Google “Unipolar Steeping Motor M35SP-9 C5870-60004” the video link will be there. I hope this of use to you, Erni.

Vielen dank,
Le Scare

PS #High Embarassment Factor# - Also realised that I got L/R wrong way round in my description for second photo.

Magician: M35S1N and M35SP , probably two different species. Why do you think it's stepper?

It has 5 wires - what other kind of motor do you know of that has 5 wires and the marking '20ohm' ?

(particularly in a printer...)

First, marking on a motor isn’t the same with type of the motor in referenced document.
Second , five wires doesn’t necessarily connected to motor itself, it could be ground, two/three for limit switch/encoder and only two for motor.
Third, asynchronous motor three phase would have 4 wires + ground.

Magician: First, marking on a motor isn't the same with type of the motor in referenced document. Second , five wires doesn't necessarily connected to motor itself, it could be ground, two/three for limit switch/encoder and only two for motor. Third, asynchronous motor three phase would have 4 wires + ground. http://en.wikipedia.org/wiki/Asynchronous_motor

Perhaps - but it's highly unlikely that you'd see anything like that in an el-cheapo desktop printer; you might see a DC motor with a limit switch or encoder mechanism, but it is just as unlikely given that you need the precision that a stepper provides (and as I noted, that is a fairly el-cheapo stepper - just look at the case construction; a quality stepper uses a machined or cast frame, not metal stampings).

scary:
I’ll give up on the controller then and just see if I can buy one.

You only need a ULN2003 or four transistors capable of 500ma (maximum) to drive this. Take a look at this tutorial and peek at the board; it’s just the ULN2003 with four resistors limiting current from the Arduino control pins (so as not to blow them out).

If you do insist on buying a controller it’s a little difficult to find them for unipolar motors. Nobody likes unipolar motors.

Nobody likes unipolar motors.

Why don't "we" like unipolar motors ????

I think they are great because it is so easy to make a drver for them, fx. using the LN2003

I've read that, for a given motor size, a bipolar stepper can deliver more torque than a unipolar. Is that correct? But yes, a unipolar stepper is easier to drive (with, say, a ULN2803).

Anachrocomputer: I've read that, for a given motor size, a bipolar stepper can deliver more torque than a unipolar. Is that correct? But yes, a unipolar stepper is easier to drive (with, say, a ULN2803).

Its not the unipolar/bipolar distinction that matters that much (unipolars waste half the copper, this is true), but the fixed-voltage v. fixed current windings that matters. Usually unipolars are fixed voltage high resistance high inductance windings - this makes them easy to drive, but limits the stepping speed considerable. A low-impedance bipolar motor usually has windings around 1 ohm, and can handle upto 2000rpm or more at high torque with a current-limited PWM high-voltage driver. Unipolars struggle to 200rpm and torque drops off rapidly with speed. Typical CNC machine motors would have a 30 to 60V driver and 3amp motors - only a few volts is wasted heating the windings and the rest is available to counter back-EMF and do work.

Of course if you don't want high performance unipolar driving is much simpler and cheaper!